International Journal of Pharmaceutics (v.415, #1-2)
Editorial Board (iii).
Personalised medicines by Vincent H.L. Lee; Alexander T. Florence (1).
Genomics and personalized medicine by Wolfgang Sadee (2-4).
The role of genomics in personalized medicine continues to undergo profound changes, in step with dramatic technological advances. Ability to sequence the entire human genome with relative ease raises expectations that we can use an individual's complete genomic blueprint to understand disease risk and predicting therapy outcomes, thereby, optimizing drug therapy. Yet, doubts persist as to what extent genetic/genomic factors influence disease and treatment outcomes or whether robust predictive biomarker tests can be developed. Encompassing more than just DNA sequences, the definition of genomics now often is taken to include transcriptomics, proteomics, metabolomics, and epigenomics, with integration of genomic and environmental factors, in an area referred to systems biology. While we can learn much about a cell's innermost workings, summation of these diverse areas is far from enabling the prediction of therapeutic outcomes. Typically, only a handful of specific biomarkers, genetic or otherwise, are ‘actionable’, i.e., they can be used to guide therapy. I will focus on pharmacogenetic biomarkers, highlighting current successes but also the main challenges that remain in optimizing individualized therapy.
‘Personalised medicine’ through ‘personalised medicines’: Time to integrate advanced, non-invasive imaging approaches and smart drug delivery systems by Daan J.A. Crommelin; Gert Storm; Peter Luijten (5-8).
In this Commentary, the authors briefly discuss the status of efforts to individualize therapeutic interventions. They differentiate between the widely discussed idea of further shaping ‘personalized medicine’ approaches by using (new) biomarkers and (molecular) imaging techniques and the much less debated topic of ‘personalized medicines’: medicines, often carrier based, specifically geared to treat the individual patient optimally.An example where ‘personalized medicine’ is achieved by ‘personalized medicines’ is described: a smart drug delivery system is activated at the target site by non-invasive radiation (focused ultrasonic radiation, FU) while this spatial and temporal release process is guided and monitored by MRI (Magnetic Resonance Imaging guided High Intensity Focused Ultrasonic, MRIgHIFU).
Keywords: Individualized medicine; Molecular imaging; Liposomes; High intensity focused ultrasonic radiation;
Individualized dosing regimens in children based on population PKPD modelling: Are we ready for it? by Catherijne A.J. Knibbe; Meindert Danhof (9-14).
Despite profound differences in response between children and adults, and between children of different ages, drugs are still empirically dosed in mg/kg in children. Since maturation of expression and function is typically a non-linear dynamic process which differs between biotransformation routes and pharmacological targets, paediatric dosing regimens should be based on the changing pharmacokinetic–pharmacodynamic (PKPD) relationship in children. In this respect, the population approach is essential, allowing for sparse sampling in each individual child. An example is presented on morphine glucuronidation, for which two covariates were identified and subsequently used to derive a model-based dosing algorithm for a prospective clinical trial in children. Using this novel dosing algorithm, similar morphine concentrations are expected while, depending on age, lower and higher morphine dosages are administered compared to mg/kg/h dosing. As the covariate functions may reflect system-specific information on the maturation of a specific drug-disposition pathway, its use for other drugs that share the same pathway is explored. For this purpose, prospective clinical trials and cross-validation studies are urgently needed. In conclusion, PKPD modelling and simulation studies are important to develop evidence-based and individualized dosing schemes for children, with the ultimate goal to improve drug safety and efficacy in this population.
Keywords: Children; Pharmacokinetics; Pharmacodynamics; Dosing guidelines; Paediatrics; PKPD modelling;
Does sex matter? The influence of gender on gastrointestinal physiology and drug delivery by Ana C. Freire; Abdul W. Basit; Rahul Choudhary; Chee W. Piong; Hamid A. Merchant (15-28).
Display Omitted► Personalised medicine aims to improve drug efficacy and reduce adverse effects. ► Efforts are being made to understand the physiological differences that underlie responses to drugs. ► There are gaps in our knowledge of gender differences in the gastrointestinal tract. ► This review article highlights the known gender differences in gut physiology and discusses the influence of such differences on drug disposition.We all respond differently to drugs. Personalised medicine aims to improve efficacy and reduce side effects, and efforts are being made to understand the physiological differences that underlie responses to drugs. Genetics, diet and disease state can be key; however, gender also plays an important role in pharmacokinetics, pharmacodynamics and drug toxicity. Differences in metabolism and clearance of drugs as a consequence of distinct hepatic and renal processes in males and females are now much better understood but little is known about gender differences in the gastrointestinal tract. As the recipient of all orally administered medications, differences at this level can have a major impact on drug delivery and bioavailability; yet these continue to be ignored and insufficiently studied in the context of drug disposition. The aim of this review is to highlight the known gender differences in gut physiology. Clinical case studies are presented, where possible, to illustrate the influence of these differences on drug disposition and gaps in current knowledge are highlighted to encourage further research in this area.
Keywords: Personalized medicines; Gastrointestinal physiology; Stomach; Small intestine; Colon; Motility; Transit; Fluids; Microbiota; pH; Pharmacokinetics; Absorption; Bioavailability; Population variability;
Personalised medicines: More tailored drugs, more tailored delivery by Alexander T. Florence; Vincent H.L. Lee (29-33).
The mechanisms of drug release in poly(lactic-co-glycolic acid)-based drug delivery systems—A review by Susanne Fredenberg; Marie Wahlgren; Mats Reslow; Anders Axelsson (34-52).
Display Omitted► We analyze the complex picture of drug release from PLGA drug delivery systems. ► We focus on release mechanisms, discuss ways to study it and review the literature. ► Four true release mechanisms were identified. ► The release rate are affected by many interacting factors, for example polymer erosion. ► The complexity provides many possible ways of modifying drug release.Poly(d,l-lactic-co-glycolic acid) (PLGA) is the most frequently used biodegradable polymer in the controlled release of encapsulated drugs. Understanding the release mechanisms, as well as which factors that affect drug release, is important in order to be able to modify drug release. Drug release from PLGA-based drug delivery systems is however complex. This review focuses on release mechanisms, and provides a survey and analysis of the processes determining the release rate, which may be helpful in elucidating this complex picture. The term release mechanism and the various techniques that have been used to study release mechanisms are discussed. The physico-chemical processes that influence the rate of drug release and the various mechanisms of drug release that have been reported in the literature are analyzed in this review, and practical examples are given. The complexity of drug release from PLGA-based drug delivery systems can make the generalization of results and predictions of drug release difficult. However, this complexity also provides many possible ways of solving problems and modifying drug release. Basic, generally applicable and mechanistic research provides pieces of the puzzle, which is useful in the development of controlled-release pharmaceuticals.
Keywords: Release mechanism; PLGA; Pore formation; Pore closure; Diffusion; Degradation;
Liposome preparation using a hollow fiber membrane contactor—Application to spironolactone encapsulation by A. Laouini; C. Jaafar-Maalej; S. Sfar; C. Charcosset; H. Fessi (53-61).
. Preparation of liposomes using a membrane contactor.Display Omitted► We present a novel liposome preparation strategy using a hollow fiber module. ► The technique is fast, reproducible and has a potential for industrial production. ► We studied the influence of process parameters on liposome characteristics. ► High entrapment efficiency was achieved when filling liposomes with spironolactone. ► Spironolactone release from liposomes was rapid and complete within 5 h.In this study, we present a novel liposome preparation technique suitable for the entrapment of pharmaceutical and cosmetic agents. This new method uses a membrane contactor in a hollow fiber configuration. In order to investigate the process, key parameters influence on the liposome characteristics was studied. It has been established that the vesicle size distribution decreased with the organic phase pressure decrease, the phospholipid concentration decreases and the aqueous to organic phase volume ratio increases. Liposomes were filled with a hydrophobic drug model, spironolactone that could be used for a paediatric medication. The mean size of drug-free and drug-loaded liposomes was, respectively, 113 ± 4 nm and 123 ± 3 nm. The zeta potential of drug-free and drug-loaded liposomes was, respectively, −43 ± 0.7 mV and −23 ± 0.6 mV. High entrapment efficiency values were successfully achieved (93 ± 1.12%). Transmission electron microscopy images revealed nanometric sized and spherical shaped oligo-lamellar vesicles. The release profile showed a rapid and complete release within about 5 h. Additionally, special attention was paid on process reproducibility and long term lipid vesicles stability. Results confirmed the robustness of the hollow fiber module based technique. Moreover, the technique is simple, fast and has a potential for continuous production of nanosized liposome suspensions at large scale.
Keywords: Liposome; Spironolactone; Hollow fiber module; Membrane contactor; Scale-up;
Effect of crystallisation conditions and feedstock morphology on the aerosolization performance of micronised salbutamol sulphate by M.H. Shariare; M. de Matas; P. York (62-72).
Salbutamol sulphate (SS) used in dry powder inhalers requires drug particles in the respirable size range of 1–5 μm to achieve a suitable therapeutic effect. The aim of this study was therefore to determine strategies for controlling drug substance characteristics pre and post-crystallisation to facilitate the production of micronised SS with desirable particle attributes for optimal delivery as an inhaled aerosol. SS batches were crystallised using an antisolvent method to produce a range of crystal morphologies. Air jet milling was then used to reduce the size of crystallised SS particles. Starting materials and micronised batches of SS were characterised in the solid state using a range of techniques with subsequent assessment of aerosol properties.Assessment of the aerodynamic characteristics of micronised SS delivered by DPI (without any carrier) indicated that fine particle fraction and emitted dose as a percentage of the total recovered dose were dependent on the quality attributes of the micronised SS, which were directly linked to the degree of imperfections and the morphology of the crystalline feedstock used in micronisation.Aerosolization performance of micronised SS can be optimised by manipulation of feedstock characteristics through crystal engineering and through definition of optimal processing conditions for micronisation.
Keywords: Dry powder inhaler; Crystallisation; Particle size reduction; Fine particle fraction; Salbutamol sulphate;
In vitro and in vivo evaluation of an intraocular implant for glaucoma treatment by Mădălina V. Natu; Manuel N. Gaspar; Carlos A. Fontes Ribeiro; António M. Cabrita; Hermínio C. de Sousa; M.H. Gil (73-82).
Implantable disks for glaucoma treatment were prepared by blending poly(ɛ-caprolactone), PCL, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) and dorzolamide. Their in vivo performance was assessed by their capacity to decrease intraocular pressure (IOP) in normotensive and hypertensive eyes. Drug mapping showed that release was complete from blend disks and the low molecular weight (MW) PCL after 1 month in vivo. The high MW PCL showed non-cumulative release rates above the therapeutic level during 3 months in vitro. In vivo, the fibrous capsule formation around the implant controls the drug release, working as a barrier membrane. Histologic analysis showed normal foreign body reaction response to the implants. In normotensive eyes, a 20% decrease in IOP obtained with the disks during 1 month was similar to Trusopt® eyedrops treatment. In hypertensive eyes, the most sustained decrease was shown by the high MW PCL (40% after 1 month, 30% after 2 months). It was shown that the implants can lower IOP in sustained manner in a rabbit glaucoma model.
Keywords: Poly(ɛ-caprolactone); Subconjunctival implant; Controlled drug release; In vivo; Intraocular pressure; Glaucoma;
Preparation and characterization of pH-independent sustained release tablet containing solid dispersion granules of a poorly water-soluble drug by Huyen Thi Thanh Tran; Jun Bom Park; Ki-Hyuk Hong; Han-Gon Choi; Hyo-Kyung Han; Jaehwi Lee; Kyung Taek Oh; Beom-Jin Lee (83-88).
pH-independent release of drug was achieved from sustained release tablets containing solid dispersion granules in gastric fluid (pH 1.2) for 2 h and subsequently in intestinal fluid (pH 6.8) for 10 h. Energy dispersive X-ray spectroscopy (EDS) images indicated the uniform distribution of Cl (LST, Aerosil 300) and Si (Aerosil 300) in the SD granules.Display Omitted► A free-flowing solid dispersion (SD) granule was prepared by adsorbing the melt of the drug and poloxamer 188 onto the surface of an adsorbent, followed by direct compression with polyethylene oxide to obtain an SD-loaded sustained release (SD-SR) matrix tablet. ► Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) images indicated adsorption of SD granules onto the surface of the adsorbent. ► The SD granules dissolved completely within 10 min, a dissolution rate much higher than that of pure LST. ► A pH-independent sustained release of LST from the SD-SR tablet was achieved for 2 h in gastric fluid (pH 1.2) and for 10 h in intestinal fluid (pH 6.8).Sustained release (SR) tablets containing solid dispersions (SD) granules of a poorly water-soluble drug were prepared to investigate the controlled pH-independent release of the drug. Losartan potassium (LST), an anti-hypertensive agent was chosen as a model drug because of its pH-dependent solubility and short elimination half-life. Poloxamer 188 was used as an SD carrier. A free-flowing SD granule was prepared by adsorbing the melt of the drug and poloxamer 188 onto the surface of an adsorbent, Aerosil 300 (fumed silicon dioxide), followed by direct compression with polyethylene oxide (PEO, 5 × 106) to obtain an SD-loaded SR (SD-SR) matrix tablet. Differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) revealed partially amorphous structures of the drug in the SD granules. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) images indicated adsorption of SD granules onto the surface of the adsorbent. The SD granules dissolved completely within 10 min, a dissolution rate much higher than that of pure LST. Moreover, pH-independent sustained release of LST from the SD-SR tablet was achieved for 2 h in gastric fluid (pH 1.2) and for 10 h in intestinal fluid (pH 6.8). A combination of SD techniques using surface adsorption and SR concepts is a promising approach to control the release rate of poorly water-soluble drugs in a pH-independent manner.
Keywords: Solid dispersion granules; Surface adsorption; Sustained release tablet; pH-independent release; EDS imaging;
Enhanced dissolution and bioavailability of biochanin A via the preparation of solid dispersion: In vitro and in vivo evaluation by Hyo-Kyung Han; Beom-Jin Lee; Hyoung-Kyu Lee (89-94).
. The solid dispersions using the mixture of Solutol® HS15 and HPMC 2910 appeared to be effective to improve the dissolution and oral exposure of biochanin A.Display Omitted► SDs of biochanin A with Solutol® HS15 and HPMC 2910 were prepared and evaluated. ► SDs achieved the rapid and complete drug release (approximately 100% within 1 h). ► SDs significantly improved the oral exposure of biochanin A in rats.The present study aimed to improve the bioavailability of biochanin A, a poorly soluble bioflavonoid, via the preparation of solid dispersion (SD) using Solutol® HS15 and HPMC 2910. Solubility of biochanin A was enhanced by 8–60 folds as the drug-carrier ratio was increased in SDs. Furthermore, compared to pure biochanin A or physical mixture (PM), SDs significantly improved the dissolution rate and the extent of drug release. Particularly, SDs (Drug:Solutol® HS15:HPMC 2910 = 1:5:5 or 1:10:10) achieved the rapid and complete drug release (approximately 100% within 1 h) at pH 6.8. The XRD patterns indicated that SDs might enhance the solubility of biochanin A by changing the drug crystallinity to amorphous state in addition to the solubilizing effect of hydrophilic carriers. The improved dissolution of biochanin A via SD formulation appeared to be well correlated with the enhanced oral exposure of biochanin A in rats. After an oral administration of SD (Drug:Solutol® HS15:HPMC 2910 = 1:10:10), C max and AUC of biochanin A were increased by approximately 13 and 5 folds, respectively, implying that SDs could be effective to improve the bioavailability of biochanin A. In conclusion, solid dispersion with Solutol® HS15 and HPMC 2910 appeared to be promising to improve the dissolution and oral exposure of biochanin A.
Keywords: Biochanin A; Solid dispersion; Dissolution; Bioavailability;
Characterisation of the interactive properties of microcrystalline cellulose–carboxymethyl cellulose hydrogels by G.H. Zhao; N. Kapur; B. Carlin; E. Selinger; J.T. Guthrie (95-101).
The process of the hydrogel broken down under the shear.Combinations of microcrystalline cellulose (MCC) and sodium carboxymethyl cellulose (Na-CMC) are commonly used as stabilising agents and suspending agents in pharmaceutical formulations. This paper is based on a study of the interactions that take place during the process of hydrogel formation, break down, and recovery. Also considered is the binding that occurs between the MCC and the Na-CMC.Avicel RC 591, a processed mixture of MCC and Na-CMC, is one of the more commonly used commercial suspending agents for aqueous compositions. Avicel RC 591 is used as an effective, blended stabilising agent. In this study, the contributions made by each of the components of Avicel RC 591 have been rationalised by monitoring the behaviour of the individual components in Avicel RC 591 suspensions or solutions. The hydrogels that are formed by Avicel RC 591 and by their laboratory formulated equivalent, which is spray dried (MCC + Na-CMC), have been characterised by confocal microscopy scanning electron microscopy and by dynamic light scattering. A 3D network structure that is formed by the MCC, in Avicel RC 591 is visualised. This network is supported by hydrogen bonding and by ionic interactions among and between the MCC, the Na-CMC and water. The strength of the network determines the physical properties of the hydrogel system, as seen in the rheological behaviour.
Keywords: Hydrogel; Interaction; Composites; Rheology;
Near-infrared spectroscopy (NIRS) and chemometric analysis of Malaysian and UK paracetamol tablets: A spectral database study by Mazlina M. Said; Simon Gibbons; Anthony C. Moffat; Mire Zloh (102-109).
Display Omitted► We create the spectral database of purchased paracetamol tablets. ► We validate the use of database search algorithms for sample identification. ► We examine the use of database for monitoring of product quality. ► The variability of NIR spectra of paracetamol tablets depends on sample origin.The influx of medicines from different sources into healthcare systems of developing countries presents a challenge to monitor their origin and quality. The absence of a repository of reference samples or spectra prevents the analysis of tablets by direct comparison. A set of paracetamol tablets purchased in Malaysian pharmacies were compared to a similar set of sample purchased in the UK using near-infrared spectroscopy (NIRS). Additional samples of products containing ibuprofen or paracetamol in combination with other actives were added to the study as negative controls. NIR spectra of the samples were acquired and compared by using multivariate modeling and classification algorithms (PCA/SIMCA) and stored in a spectral database. All analysed paracetamol samples contained the purported active ingredient with only 1 out of 20 batches excluded from the 95% confidence interval, while the negative controls were clearly classified as outliers of the set. Although the substandard products were not detected in the purchased sample set, our results indicated variability in the quality of the Malaysian tablets. A database of spectra was created and search methods were evaluated for correct identification of tablets. The approach presented here can be further developed as a method for identifying substandard pharmaceutical products.
Keywords: NIRS; Spectral database; Paracetamol; Malaysia; Counterfeit medicines; SIMCA; PCA; Qualitative study; Chemometrics;
Quantification of polymorphic impurity in an enantiotropic polymorph system using differential scanning calorimetry, X-ray powder diffraction and Raman spectroscopy by Yi Li; Pui Shan Chow; Reginald B.H. Tan (110-118).
Display Omitted► Effective method for quantitative analysis of small amount of polymorphic impurity. ► Sulfamerazine as model compound. ► Effectiveness and accuracy of PXRD, Raman microscopy and DSC compared. ► Low heating rate in DSC allowed complete polymorph transformation. ► DSC provides a rapid and accurate method for offline quantification. ► PXRD provides a non-destructive, non-contact analysis.The ability to detect and quantify polymorphism of pharmaceuticals is critically important in ensuring that the formulated product delivers the desired therapeutic properties because different polymorphic forms of a drug exhibit different solubilities, stabilities and bioavailabilities. The purpose of this study is to develop an effective method for quantitative analysis of a small amount of one polymorph within a binary polymorphic mixture. Sulfamerazine (SMZ), an antibacterial drug, was chosen as the model compound. The effectiveness and accuracy of powder X-ray diffraction (PXRD), Raman microscopy and differential scanning calorimetry (DSC) for the quantification of SMZ polymorphs were studied and compared. Low heating rate in DSC allowed complete transformation from Form I to Form II to take place, resulting in a highly linear calibration curve. Our results showed that DSC and PXRD are capable in providing accurate measurement of polymorphic content in the SMZ binary mixtures while Raman is the least accurate technique for the system studied. DSC provides a rapid and accurate method for offline quantification of SMZ polymorphs, and PXRD provides a non-destructive, non-contact analysis.
Keywords: Polymorphic impurity; Quantification; PXRD; DSC; Raman; Sulfamerazine;
Transdermal delivery of selegiline from alginate–Pluronic composite thermogels by Chih-Chieh Chen; Chia-Lang Fang; Saleh A. Al-Suwayeh; Yann-Lii Leu; Jia-You Fang (119-128).
Representative visual inspection of the aqueous copolymer system at 15 °C (A), 20 °C (B), 25 °C (C), 30 °C (D), and 35 °C (E) (left to right: PF127 (20%), alginate and PF127 blending (A + P, 20% + 0.63%), and the alginate–Pluronic F127 composite copolymer (AP, 15%)).The present work was carried out to design a practical, controlled-release transdermal system for selegiline using thermosensitive hydrogels. The copolymers of alginate and Pluronic F127 (PF127) were used to design thermogels by either physical blending (A + P) or chemical grafting (AP). The thermogels were characterized in terms of the sol–gel temperature, scanning electron microscopy (SEM), degradation ratio, and skin permeation behavior. The chemical grafting of alginate to PF127 could delay the sol–gel temperature from 24.1 to 30.4 °C, which is near the temperature of the skin surface. The gelling temperature of the physical mixture of alginate and PF127 (A + P) did not significantly differ. The porosity of the A + P structure was greater compared to that of the AP structure. AP thermogels were regularly degraded, with 60% of the gel matrix remaining after a 48-h incubation. PF127 and A + P hydrogels showed almost no degradation. The results of skin permeation across porcine skin and nude mouse skin suggested that the thermogels could produce sustained selegiline release, with AP showing the most-sustained permeation. AP hydrogels exhibited linear permeation properties for the transdermal delivery of selegiline. Inter-subject variations in skin permeation were reduced by incorporation of the thermogel. Such a thermosensitive hydrogel can be advantageous as a topical therapeutic formulation for selegiline.
Keywords: Transdermal delivery; Selegiline; Thermogel; Alginate; Pluronic F127;
New clopidogrel napadisilate salt and its solid dispersion with improved stability and bioequivalence to the commercial clopidogrel bisulphate salt in beagle dogs by Yong-Il Kim; Kyung Soo Kim; Kwee-Hyun Suh; Srinivasan Shanmugam; Jong Soo Woo; Chul Soon Yong; Han-Gon Choi (129-139).
Stability (A) and pharmacokinetics (B and C) of clopidogrel bisulphate (commercial salt) and clopidogrel napadisilate-loaded solid dispersion; (B) clopidogrel; (C) SR26334.The purpose of this study was to develop a novel clopidogrel napadisilate-loaded solid dispersion with improved stability and bioequivalence to the clopidogrel bisulphate-loaded commercial product. Clopidogrel napadisilate prepared in this study appeared as a white crystalline powder unlike clopidogrel base. However, this salt did not improve the solubility of clopidogrel, even with improved stability compared to clopidogrel bisulphate. To improve the solubility of clopidogrel napadisilate, a novel clopidogrel napadisilate-loaded solid dispersion was prepared by the spray-drying technique using HPMC and colloidal silica, and the physicochemical properties, dissolution and bioavailability in beagle dogs were evaluated compared to the clopidogrel bisulphate-loaded commercial product. The solid dispersion composed of clopidogrel napadisilate, HPMC and colloidal silica at a weight ratio of 11.069/3/3.5 improved solubility by 6.5-fold compared to clopidogrel napadisilate, even if it did not improve drug solubility compared to clopidogrel bisulphate. However, unlike clopidogrel bisulphate, this formulation improved the stability of clopidogrel. Furthermore, the clopidogrel napadisilate solid dispersion-loaded tablet showed similar dissolution to the clopidogrel bisulphate-loaded commercial product and was bioequivalent to the commercial product in beagle dogs. Thus, this clopidogrel napadisilate-loaded solid dispersion could be a promising candidate for improving the stability and bioavailability of clopidogrel.
Keywords: Clopidogrel napadisilate; Solid dispersion; Stability; Solubility; Bioavailability; Bioequivalence;
Determination of parameters for successful spray coating of silicon microneedle arrays by Marie G. McGrath; Anto Vrdoljak; Conor O’Mahony; Jorge C. Oliveira; Anne C. Moore; Abina M. Crean (140-149).
Silicon microneedle arrays spray coated with carboxymethylcellulose.Coated microneedle patches have demonstrated potential for effective, minimally invasive, drug and vaccine delivery. To facilitate cost-effective, industrial-scale production of coated microneedle patches, a continuous coating method which utilises conventional pharmaceutical processes is an attractive prospect. Here, the potential of spray-coating silicon microneedle patches using a conventional film-coating process was evaluated and the key process parameters which impact on coating coalescence and weight were identified by employing a fractional factorial design to coat flat silicon patches. Processing parameters analysed included concentration of coating material, liquid input rate, duration of spraying, atomisation air pressure, gun-to-surface distance and air cap setting. Two film-coating materials were investigated; hydroxypropylmethylcellulose (HPMC) and carboxymethylcellulose (CMC). HPMC readily formed a film-coat on silicon when suitable spray coating parameter settings were determined. CMC films required the inclusion of a surfactant (1%, w/w Tween 80) to facilitate coalescence of the sprayed droplets on the silicon surface. Spray coating parameters identified by experimental design, successfully coated 280 μm silicon microneedle arrays, producing an intact film-coat, which follows the contours of the microneedle array without occlusion of the microneedle shape. This study demonstrates a novel method of coating microneedle arrays with biocompatible polymers using a conventional film-coating process. It is the first study to indicate the thickness and roughness of coatings applied to microneedle arrays. The study also highlights the importance of identifying suitable processing parameters when film coating substrates of micron dimensions. The ability of a fractional factorial design to identify these critical parameters is also demonstrated. The polymer coatings applied in this study can potentially be drug loaded for intradermal drug and vaccine delivery.
Keywords: Microneedle; Spray coat; Silicon; Hydroxypropylmethylcellulose; Carboxymethylcellulose;
Oral peptide delivery by tetraether lipid liposomes by Johannes Parmentier; Bernhard Thewes; Felix Gropp; Gert Fricker (150-157).
Tetraether lipids show only a low uptake after oral administration of liposomes. The oral bioavailability of octreotide can be increased several folds by tetraether lipid liposomes.The aim of this study is to improve of oral peptide delivery by a novel type of liposomes containing tetraether lipids (TELs) derived from archaea bacteria. Liposomes were used for the oral delivery of the somatostatin analogue octreotide. TELs were extracted from Sulfolobus acidocaldarius and subsequently purified to single compounds. Liposomes were prepared by the film method followed by extrusion. Vesicles in size between 130 and 207 nm were obtained as confirmed by photon correlation spectroscopy. The pharmacokinetics of radiolabeled TELs in liposomes was investigated after oral administration to rats. 1.6% of the applied radioactivity in fed and 1.5% in fasted rats was recovered in the blood and inner organs after 2 h, while most of the radioactivity remained in the gastro-intestinal tract. After 24 h the percentage of radioactivity in inner organs was reduced to 0.6% in fed rats, respectively 1.0% in fasted animals. Several liposomal formulations containing dipalmitoyl phosphatidylcholine (DPPC) and TELs in different ratios were loaded with octreotide and orally administered. Liposomes with 25% TEL could improve the oral bioavailability of octreotide 4.1-fold and one formulation with a cationic TEL derivative 4.6-fold. TEL-liposomes probably act by protecting the peptide in the gastro–intestinal tract.
Keywords: Protein; Oral delivery; Bioavailability; Stability; GI tract;
Assessment of biological half life using in silico QSPkR approach: A self organizing molecular field analysis (SOMFA) on a series of antimicrobial quinolone drugs by Honey Goel; V.R. Sinha; Suresh Thareja; Saurabh Aggarwal; Manoj Kumar (158-163).
A 3D-QSPkR methodology using self organizing molecular field analysis was employed to rationalize the pharmacokinetic properties in order to obtain an insight for the generation of novel molecular architecture of quinolones with optimal half life and improved biological profile.The quinolones belong to a family of synthetic potent broad-spectrum antibiotics and particularly active against gram-negative organisms, especially Pseudomonas aeruginosa. A 3D-QSPkR approach has been used to obtain the quantitative structure pharmacokinetic relationship for a series of quinolone drugs using SOMFA. The series consisting of 28 molecules have been investigated for their pharmacokinetic performance using biological half life (t 1/2). A statistically validated robust model for a diverse group of quinolone drugs having flexibility in structure and pharmacokinetic profile (t 1/2) obtained using SOMFA having good cross-validated correlation coefficient r cv 2 (0.6847), non cross-validated correlation coefficient r 2 values (0.7310) and high F-test value (33.9663). Analysis of 3D-QSPkR models through electrostatic and shape grids provide useful information about the shape and electrostatic potential contributions on t 1/2. The analysis of SOMFA results provide an insight for the generation of novel molecular architecture of quinolones with optimal half life and improved biological profile.
Keywords: Quinolone drugs; Biological half life; 3D-QSPkR; SOMFA-model;
Effect of physical ageing on the performance of dexamethasone loaded PLGA microspheres by Archana Rawat; Diane J. Burgess (164-168).
DSC thermograms of dexamethasone loaded PLGA microspheres showed an increase in the T g and enthalpy of relaxation with time following storage at 25 °C. There was a slight change in the in vitro release profile of the microspheres following storage at 25 °C for 12 months.The phenomenon of physical ageing or structural relaxation and its effect on the performance of dexamethasone loaded poly(lactide-co-glycolide) (PLGA) microspheres was evaluated. Microspheres were incubated at temperatures (−20 (control), 4 and 25 °C) below their glass transition temperature for 12 months. Physical ageing occurred in microspheres incubated at 25 °C due to structural relaxation of the polymer chains which occurs to achieve a lower equilibrium energy state. Significant physical ageing was not observed in microspheres incubated at 4 °C due to the lower molecular mobility of PLGA. The rate of structural relaxation (at 25 °C) was a function of free volume which decreased with time. The microspheres incubated at 25 °C for 12 months resulted in a slower release profile after day 25 when compared to the control microspheres. This was speculated to be due to a reduction in free volume upon physical ageing which in turn may reduce water absorption and retention of acidic degradation products in the PLGA matrix, hence reducing the degradation rate of PLGA. Therefore, exposure to ambient temperature during storage, shipping or handling may cause physical ageing in PLGA microspheres and hence, their performance may be affected. Storage temperatures of 4 °C or lower may be considered appropriate for PLGA microspheres.
Keywords: PLGA microspheres; Physical ageing; Structural relaxation; In vitro release;
Synergistic effect of 1,4-cyclohexanediol and 1,2-hexanediol on percutaneous absorption and penetration of metronidazole by Nan Li; Weibu Jia; Yan Zhang; Fengping Tan; Jerry Zhang (169-174).
The objective of this study was to investigate the percutaneous absorption of metronidazole (MTZ) in the topical formulations containing a combination of 1,4-cyclohexanediol and 1,2-hexanediol. Six formulations were studied in an in vitro hairless mouse skin model using Franz Diffusion Cell. MTZ was applied at infinite doses (50 mg and 100 mg of the formulations, which correspond to 375 and 750 μg of MTZ, respectively). Based on the flux values and retardation ratio (RR), a synergistic retardation effect on percutaneous absorption of MTZ was observed for the formulations containing a combination of 1,4-cyclohexanediol and 1,2-hexanediol (RRs are 0.40 for 375 μg dose and 0.69 for 750 μg dose, respectively). Interestingly, retention of MTZ in epidermis and dermis layer showed no significant differences (p > 0.05) between the formulations containing the retardant combination and control formulations. In other words, the retardant combination in the formulation decreases MTZ fluxes while maintaining similar level of retention in epidermis and dermis layer when compared to the control formulations. These observations provide insight in formulating superior topical formulations with minimized potential systematic toxicity while maintaining therapeutic efficiency. A mechanistic explanation of the observed synergistic effect is proposed.
Keywords: 1,4-Cyclohexanediol; 1,2-Hexanediol; Retardant; Synergistic; Percutaneous Absorption;
Paclitaxel conjugation with the analog of the gonadotropin-releasing hormone as a targeting moiety by Marie Pribylova; Marcela Dvorakova; Veronika Hanusova; Ingrid Nemethova; Lenka Skalova; Tomas Vanek (175-180).
A new targeted conjugates in which paclitaxel was used as a cytostatic compound and an analog of the gonadotropin-releasing hormone (GnRH) as a targeting moiety were synthesized. The molecule of the peptide hormone GnRH was modified to allow its connection to paclitaxel via spacer. The conjugates were prepared as prodrugs using 2′-hydroxyl group of paclitaxel. 4-Maleimidobutyric acid and chloroacetic acid served as spacers. The structures of the prepared derivatives were analysed by NMR and HR-MS. The conjugates MP264 and MP265 were chosen and their antiproliferative effect was tested in the breast cancer cell line MCF-7 using the MTT test of cell viability and neutral red uptake test. In MCF-7 cells, conjugate MP265 showed higher antiproliferative effect than paclitaxel alone. Receptor saturation tests showed that the unconjugated peptide analog of GnRH decreased efficacy of conjugate MP265 in concentration- and time-dependent manner. In conclusion, the paclitaxel conjugate with the analog of GnRH exhibited targeted antiproliferative effect for which its further testing will be implemented.
Keywords: Paclitaxel; GnRH; Targeted drug delivery; Cancer;
Sunscreen products: What do they protect us from? by C. Couteau; O. Couteau; S. Alami-El Boury; L.J.M. Coiffard (181-184).
Whereas for fifty or so years acquiring a tan has been the trend for aesthetic reasons relating to current beauty criteria, the health authorities are now advocating vigilance in this area, prompted by the knowledge of the harmful effects of the sun, especially from its ultra-violet rays. In the European Union, sunscreen products are considered cosmetics and tests on their effectiveness can be performed in vivo or in vitro to determine four effectiveness indicators: the SPF (Sun Protection Factor), the PF-UVA (UVA Protection Factor), the SPF/PF-UVA ratio and the critical wave length. It is the erythemal SPF which is measured in the vast majority of cases: it can therefore be confirmed that sunscreen products protect us from sunburn under good conditions of use. We thought it would be interesting to calculate other indicators to assess protection against non-melanoma skin cancers (NMSC) and to quantify the effectiveness of the product against UVA1 or UVA2. To characterize the products tested, we have determined in vitro different SPF and PF-UVA values, by using not just the erythemal weighting factor but also the weighting factor relating to the non-melanocytic skin cancer (SPFcnm and PF-UVAcnm), by getting away from any weighting factor (SPFm and PF-UVAm) and lastly, by varying the integration limits to quantify the effectiveness of the tested product in the UVB (290–320 nm), UVA1 (340–400 nm) and UVA2 320–340 nm) fields. In this way, and using these new indicators, we have been able to qualify eleven commercial products—ten cosmetic products and one medical device. It can be interesting to take into account the non-melanocytic skin cancer protection in order to qualify the sunscreen products.
Keywords: SPF; PF-UVA; In vitro test; Non-melanoma skin cancer; Erythema;
Simultaneous micronization and surface modification for improvement of flow and dissolution of drug particles by Xi Han; Chinmay Ghoroi; Daniel To; Yuhua Chen; Rajesh Davé (185-195).
Simultaneous micronization and surface modification of drug particles is considered in order to mitigate disadvantages of micronization, e.g., agglomeration, poor flowability, marginal increase in surface area and low bulk density. Particles of ibuprofen (102 μm), a model drug, pre-blended with hydrophilic nano-silica, are micronized down to 10 and 5 μm in a continuous fluid energy mill (FEM) to obtain fine surface modified particles. The solid feeding rate and the grinding pressure are shown as critical parameters for achieving the desired particle size and size distribution. The powder properties were characterized via SEM, laser scattering, powder rheometer with shear-cell, and dissolution test. Significant improvement in flow properties and dissolution rate was observed when micronization accompanied surface modification. Additionally, co-grinding with water-soluble polymer during micronization led to further increase in bulk density and more enhanced dissolution rate improvement, which is attributed to improved wettability. XRD, DSC and Raman were used to examine crystallinity, indicating minimal detectable physical transformation with FEM processed ibuprofen. The surface modified, micronized powders also showed improved dispersion, higher bulk densities (>0.4 g/ml), reduced electrostatic, and higher flowability (FFC ≥ 6) compared to just micronized powder (0.19 g/ml, FFC = 1.0), indicating they may be used in high drug loaded formulations amenable to direct compression.
Keywords: Fluid energy mill (FEM); Dry coating; Micronization; Flowability; Dissolution rate; Co-grinding;
A combined technique based on prilling and microwave assisted treatments for the production of ketoprofen controlled release dosage forms by Giulia Auriemma; Pasquale Del Gaudio; Anna Angela Barba; Matteo d’Amore; Rita P. Aquino (196-205).
In this study the feasibility of joining prilling and microwave (MW) assisted treatments as combined technique to produce controlled release alginate beads was tested. Beads were produced by prilling (laminar jet break-up) using different polymer concentrations and loaded with ketoprofen, a slightly soluble non-steroidal anti-inflammatory BCS class II drug characterized by low melting point. MW assisted treatments applied using different irradiating conditions were performed as drying/curing step. The effect of formulation conditions and process variables on drying kinetics, particle micromeritics, shape, surface and inner characteristics of the matrix as well as drug loading and drug release behaviour was studied (USP pH change method). The properties of MW dried particles were compared to those dehydrated by convective methods (room conditions and tray oven 105 °C).Results showed that MW dried ketoprofen loaded beads were obtained in a very narrow dimensional range retaining shape and size distribution of the hydrates particles. Compared to the traditional drying methods, MW treatments were able to strongly increase drying rate of the hydrated beads achieving faster and controllable dehydration kinetics. Moreover, different regimes of irradiation affected structural properties of the particles such as matrix porosity as well as the solid state of the loaded drug. DSC, X-ray and FTIR analyses indicated complex chemical interactions between the drug and polymer matrix induced by MW, related with the regime of irradiation, that contributes to the differences in release profiles. In fact, MW treatments under different time and irradiating regimes are able to modulate drug release from alginate beads; high levels of irradiation led to beads suitable for immediate release oral dosage forms whereas the lowest regime of irradiation led to beads that achieved a prolonged/sustained release of the drug till 8 h in simulated intestinal medium. This study showed that prilling in combination with microwave treatments is a useful and simple tandem technique to prepare dextran-based dried beads.
Keywords: Prilling; Microwave; Drug release; Drying rate; Ketoprofen; Alginate;
Synthesis and characterization of a novel ester-based nucleoamino acid for the assembly of aromatic nucleopeptides for biomedical applications by Giovanni N. Roviello; Domenica Musumeci; Enrico M. Bucci; Carlo Pedone (206-210).
In this work, we report a technological approach to a novel Fmoc-protected nucleoamino acid, based on l-tyrosine, carrying the DNA nucleobase on the hydroxyl group by means of an ester bond, suitable for the solid-phase synthesis of novel aromatic nucleopeptides of potential interest in biomedicine. After ESI-MS and NMR characterization this building block was used for the assembly of a thymine-functionalized tetrapeptide, composed of nucleobase-containing and underivatized l-tyrosine moieties alternated in the backbone.
Keywords: Tyrosine; Peptide; Aromatic;
Layer-by-layer microcapsules templated on erythrocyte ghost carriers by Mutukumaraswamy Shaillender; Rongcong Luo; Subbu S. Venkatraman; Björn Neu (211-217).
Layer-by-layer (LbL) microcapsules based on red blood cell ghosts provide a simple mean for the preparation of loaded microcapsules. The LbL shell protects the capsules from decomposition and allows adjusting the release profiles of the encapsulated molecules.This work reports the fabrication of layer-by-layer (LbL) microcapsules that provide a simple mean for controlling the burst and subsequent release of bioactive agents. Red blood cell (RBC) ghosts were loaded with fluorescently labeled dextran and lysozyme as model compounds via hypotonic dialysis with an encapsulation efficiency of 27–31%. It is demonstrated that these vesicles maintain their shape and integrity and that a uniform distribution of the encapsulated agents within these carriers is achieved. The loaded vesicles were then successfully coated with the biocompatible polyelectrolytes, poly-l-arginine hydrochloride and dextran sulfate. It is demonstrated that the release profiles of the encapsulated molecules can be regulated over a wide range by adjusting the number of polyelectrolyte layers. In addition, the LbL shell also protects the RBC ghost from decomposition thereby potentially preserving the bioactivity of encapsulated drugs or proteins. These microcapsules, consisting of an RBC ghost coated with a polyelectrolyte multilayer, provide a simple mean for the preparation of loaded LbL microcapsules eliminating the core dissolution and post-loading of bioactive agents, which are required for conventional LbL microcapsules.
Keywords: Polyelectrolyte; Layer by layer; Erythrocyte ghost; Microcapsule;
Dual imaging of mRNA and protein production: An investigation of the mechanism of heterogeneity in cationic lipid-mediated transgene expression by Hidetaka Akita; Yuko Umetsu; Dai Kurihara; Hideyoshi Harashima (218-220).
Display Omitted► The mechanism underlying this heterogeneity in a post-nuclear transport process is investigated ► Dual imaging system of mRNA and its encoded protein in a single cell is established ► Correlation was poor in a scattered plot of mRNA expression versus protein production in individual cells ► Cell-to-cell differences in the translation process are also a key factor in heterogeneous gene expressionHeterogeneity of transgene expression is a severe disadvantage in the use of cationic lipid-mediated gene vectors. We previously demonstrated that heterogeneity of the post-nuclear delivery process, as well as intracellular trafficking (i.e. nuclear delivery) is a major determinant in the overall heterogeneity in gene expression, when plasmid DNA (pDNA) is transfected to HeLa cells using a lipoplex. In this study, we explored the mechanism underlying this heterogeneity in a post-nuclear transport process by the dual imaging of mRNA and its encoded protein (histone H2B-tagged mTFP1; mTFP1-H2B) in a single cell. To establish a highly sensitive imaging system for mRNA, we used fluorescence in situ hybridization (FISH) combined with tyramide signal amplification (TSA) and a semiconductor quantum dot (QD) probe. The mRNA expression and protein production were quantified by counting the total pixel intensity in the region of interest (r.o.i.) surrounding single cells. As a result, the correlation was poor in a scattered plot of mRNA expression versus protein production in individual cells. These findings demonstrate that cell-to-cell differences in the translation process are also a key factor in heterogeneous gene expression.
Keywords: mRNA; Imaging non-viral; Gene delivery; Lipoplex; Heterogeneity;
Delivery devices for the administration of paediatric formulations: Overview of current practice, challenges and recent developments by Jennifer Walsh; Deborah Bickmann; Joerg Breitkreutz; Maryvonne Chariot-Goulet (221-231).
The European Paediatric Formulation Initiative (EuPFI), a group consisting of paediatric formulation experts from industry, academia and clinical pharmacy was founded with the aim of raising awareness of paediatric formulation issues. It is imperative that paediatric medicines can be administered accurately to ensure the correct dose is provided and that the administration device is easy to use and acceptable from the patient's and carer's perspectives. This reflection paper provides an overview of currently available paediatric administration devices and highlights some of the challenges associated with, recommendations and recent developments in delivery devices for the oral, inhaled, parenteral, nasal and ocular administration of paediatric formulations, on behalf of the EuPFI.
Keywords: Paediatric; Delivery devices; Oral; Pulmonary; Parenteral;
Nanostructured lipid carrier versus solid lipid nanoparticles of simvastatin: Comparative analysis of characteristics, pharmacokinetics and tissue uptake by Radheshyam Tiwari; Kamla Pathak (232-243).
.Display Omitted► We investigate the efficacy of nanostructured lipid carrier over solid lipid nanoparticles for simvastatin. ► We utilize Pareto charts and response surface plots to identify optimized formulation. ► Optimized NLC revealed 2.29 folds increase in bioavailability as compared to SLNs.Nanostructured lipid carrier (NLC) system of simvastatin was investigated for improvement in release, pharmacokinetics and biodistribution over its solid lipid nanoparticles (SLN). The NLC formulations prepared by solvent injection technique were optimized by 23 full factorial design. Optimized NLC was deduced on the basis of dependent variables that were analyzed using Design expert 8.0.2® software (Stat Ease, Inc., USA). Pareto charts and response surface plots were utilized to study the effect of variables on the response parameters. The optimized NLC was a suspension of nanosized homogeneous particles with significantly higher entrapment efficiency (>90%) and lower recrystallization properties (p < 0.01) than SLNs. The pharmacokinetic parameters of Tc99 labeled optimized NLC in mice, obtained using Quickcal software (Plexus, India) revealed 4.8 folds increase in bioavailability as compared to simvastatin suspension and 2.29 folds as compared to SLNs. Biodistribution study revealed preferential accumulation of NLC in the liver and this is advantageous because liver is the target organ for simvastatin. IVIVC studies demonstrated level A correlation between in vitro release and percent drug absorbed. This investigation demonstrated the superiority of NLC over SLN for improved oral delivery and it was deduced that the liquid lipid, oleic acid was the principal formulation factor responsible for the improvement in characteristics, pharmacokinetics and biodistribution of NLCs.
Keywords: Simvastatin; Nanostructured lipid carriers; Factorial design; In vitro drug release; In vitro–in vivo correlation;
Treatment of glioblastoma with poly(isohexyl cyanoacrylate) nanoparticles by Stefanie Wohlfart; Alexander S. Khalansky; Christian Bernreuther; Martin Michaelis; Jindrich Cinatl; Markus Glatzel; Jörg Kreuter (244-251).
Glioblastomas belong to the most devastating cancer diseases. For this reason, polysorbate 80 (Tween 80®)-coated poly(isohexyl cyanoacrylate) (PIHCA) (Monorex®) nanoparticles loaded with doxorubicin were developed and tested for their use for the treatment of glioblastomas. The preparation of the nanoparticles resulted in spherical particles with high doxorubicin loading. The physico-chemical properties and the release of doxorubicin from the PIHCA-nanoparticles were analysed, and the influence on cell viability of the rat glioblastoma 101/8-cell line was investigated. In vitro, the empty nanoparticles did not show any toxicity, and the anti-cancer effects of the drug-loaded nanoparticles were increased in comparison to doxorubicin solution, represented by IC50 values. The in vivo efficacy was then tested in intracranially glioblastoma 101/8-bearing rats. Rats were treated with 3 × 1.5 mg/kg doxorubicin and were sacrificed 18 days after tumour transplantation. Histological and immunohistochemical analyses were carried out to assess the efficacy of the nanoparticles. Tumour size, proliferation activity, vessel density, necrotic areas, and expression of glial fibrillary acidic protein demonstrated that doxorubicin-loaded PIHCA-nanoparticles were much more efficient than the free drug. The results suggest that poly(isohexyl cyanoacrylate) nanoparticles hold great promise for the non-invasive therapy of human glioblastomas.
Keywords: Doxorubicin; Nanoparticles; Poly(isohexyl cyanoacrylate); Glioblastoma; Histology;
Enhanced anti-tumor effect of 9-nitro-camptothecin complexed by hydroxypropyl-β-cyclodextrin and safety evaluation by Ye Jiang; Xinyi Jiang; Kitki Law; Yanzuo Chen; Jijin Gu; Wei Zhang; Hongliang Xin; Xianyi Sha; Xiaoling Fang (252-258).
Display Omitted► We have developed a novel HP-β-CD-based formulation for the delivery of 9-NC. ► 9-NC complexedin HP-β-CD presented significant anti-tumor activity both in vivo and in vitro. ► The complex ameliorated lymphocytopenia and reduced hematological toxicityin mice. ► Complexation with HP-β-CDreduced the liver toxicity and nephrotoxicity of the free 9-NC solution.The aim of this study was to evaluate the safety and anti-tumor effect of 9-nitro-camptothecin/hydroxypropyl-β-cyclodextrin (9-NC/HP-β-CD) complex on tumor-bearing mice. The in vitro anti-tumor activity was tested by MTT assay. Our study revealed that the 9-NC/HP-β-CD complex showed significant anti-tumor activity towards Skov-3, MCF-7, HeLa and S180 cell lines with IC50 values of 0.24 ± 0.09, 0.59 ± 0.20, 0.83 ± 0.11, and 6.30 ± 2.42 μg/ml, respectively, significantly superior to the free 9-NC. The in vivo therapeutic efficacy was investigated in ICR mice bearing mouse sarcoma S180. Both the high (3 mg/kg) and low (1 mg/kg) doses of 9-NC/HP-β-CD complex demonstrated high inhibition ratio of tumor growth (>75%). The subacute toxicity test was performed by measuring the body weight, histopathology, blood cell counts and clinical chemistry parameters (total bilirubin, alanine transferase, aspartate transferase, blood urea nitrogen and creatinine), and the results indicated the good safety profile of the complex. Taken together, the results suggested that the 9-NC complexed in HP-β-CD, instead of dissolved in the organic solvent, presented significant anti-tumor activity and low toxicity for the treatment of cancer.
Keywords: 9-Nitro-camptothecin; Hydroxypropyl-β-cyclodextrin; Anti-tumor; Safety evaluation;
Chitosan-modified poly(d,l-lactide-co-glycolide) nanospheres for plasmid DNA delivery and HBV gene-silencing by Ping Zeng; Yi Xu; Chunhua Zeng; Hong Ren; Mingli Peng (259-266).
Gene silencing using small interfering RNA (siRNA) has several potential therapeutic applications. In the present study, we investigated nanoparticles (NS) formulated using the biodegradable polymer, poly(d,l-lactide-co-glycolide) (PLGA) for plasmid DNA (pDNA) delivery. A cationic polymer, Chitosan (CHS), was incorporated in the PLGA matrix to improve pDNA loading efficiency and cellular uptake ability. PLGA–CHS NS were prepared by a spontaneous emulsion diffusion (SED) method, and various formulation factors were investigated. Spherical nanoparticles with particle size of around 60 nm were obtained under optimum formulation condition. The effectiveness of pDNA-loaded PLGA–CHS nanoparticles in expressing the indicative enhanced Green Fluorescent Protein (eGFP) and in slicing Hepatitis B virus (HBV) gene were examined in HepG2.2.15 cells. CHS-modified PLGA NS exhibited much higher loading efficiency than unmodified PLGA NS. CHS–PLGA NS showed a positive zeta potential, while plain-PLGA NS were negatively charged. EGFP expression studies by observation with confocal leaser scanning microscopy (CLSM) indicated that pDNA-loaded CHS–PLGA NS were more effectively taken up by the cells than plain-PLGA NS. The corresponding results showed that the HBV gene-silencing efficiency of CHS–PLGA NS was higher than those of plain-PLGA NS and naked pDNA. Thus, CHS–PLGA NS containing pDNA could provide an effective pDNA delivery system in vitro, showing that such an approach could be useful in the treatment of viral diseases in vivo.
Keywords: Poly(d,l-lactide-co-glycolide); Hepatitis B virus; Gene therapy; Chitosan; Nanoparticles;
Encapsulation enhancement and stabilization of insulin in cationic liposomes by Se-Jin Park; Soon Gil Choi; Enkhzaya Davaa; Jeong-Sook Park (267-272).
The hydration solution can be an important factor in the preparation of liposomes and can increase their encapsulation efficiency and stability.The purpose of this study was to enhance encapsulation efficiency and sustained-release delivery for parenteral administration of a protein drug. To reduce the administration frequency of protein drugs, it is necessary to develop sustained delivery systems. In this study, protein drug-loaded cationic liposomes were formulated with dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), dioleoyl-3-trimethylammonium-propane (DOTAP), and cholesterol (CH) at a molar ratio of DOPE/DOTAP/CH of 2/1.5/2. Five mol% of distearoylphosphatidyl ethanolamine polyethylene glycol (DSPE-PEG) was added prior to encapsulation of the drug into liposomes. Insulin was chosen as a model protein drug and encapsulation efficiency was evaluated in various liposomes with and without DSPE-PEG. Scanning electron microscopy was used to examine the insulin-loaded cationic liposomes. Structural analysis was performed using spectropolarimetry. Additionally, the stability and cytotoxicity of insulin-loaded cationic liposomes were evaluated. Liposomes coated with DSPE-PEG showed higher insulin encapsulation efficiency than did those without DSPE-PEG, but not significantly. Moreover, among the liposomes coated with DSPE-PEG, those hydrated with 10% sucrose showed higher encapsulation efficiency than did liposomes hydrated in either phosphate-buffered saline or 5% dextrose. In vitro release of insulin was prolonged by cationic liposomes. Our findings suggest that cationic liposomes may be a potential sustained-release delivery system for parenteral administration of protein and peptide drugs to prolong efficacy and improve bioavailability.
Keywords: Cationic liposomes; Insulin; Aqueous phase; Stability; Circular dichroism;
Lactoferrin conjugated PEG-PLGA nanoparticles for brain delivery: Preparation, characterization and efficacy in Parkinson's disease by Kaili Hu; Yanbin Shi; Wenming Jiang; Jiaying Han; Shixian Huang; Xinguo Jiang (273-283).
A novel biodegradable brain drug delivery system, the lactoferrin (Lf) conjugated polyethylene glycol-polylactide-polyglycolide (PEG-PLGA) nanoparticle (Lf-NP) was constructed in this paper with its in vitro and in vivo delivery properties evaluated by a fluorescent probe coumarin-6. Lf was thiolated and conjugated to the distal maleimide function surrounding on the pegylated nanoparticle to form Lf-NP. TEM observation and ELISA analysis confirmed the existence of active Lf on the surface of Lf-NP. The results of qualitative and quantitative uptake studies of coumarin-6 incorporated Lf-NP showed a more pronounced accumulation of Lf-NP in bEnd.3 cells than that of unconjugated nanoparticle (NP). Further uptake inhibition study indicated that the increased uptake of Lf-NP was via an additional clathrin mediated endocytosis processes. Following intravenous administration, a near 3 fold of coumarin-6 was found in the mice brain carried by Lf-NP compared to that carried by NP. Intravenous injection of urocortin loaded Lf-NP effectively attenuated the striatum lesion caused by 6-hydroxydopamine in rats as indicated by the behavioral test, the immunohistochemistry test and striatal transmitter content detection results. The cell viability test and CD68 immunohistochemistry demonstrated the acceptable toxicity of the system. All these results demonstrated that Lf-NP was a promising brain drug delivery system with reasonable toxicity.
Keywords: Lactoferrin; Blood–brain barrier (BBB); PLGA nanoparticles; Urocortin; Parkinson's disease;
Brain delivery and cellular internalization mechanisms for transferrin conjugated biodegradable polymersomes by Zhiqing Pang; Huile Gao; Yuan Yu; Jun Chen; Liangran Guo; Jinfeng Ren; Ziyi Wen; Jinghan Su; Xinguo Jiang (284-292).
Transferrin conjugated biodegradable polymersomes (Tf-PO) were exploited for efficient brain drug delivery, and its cellular internalization mechanisms were investigated. Tf-PO was prepared by a nanoprecipitation method with an average diameter of approximately 100 nm and a surface Tf molecule number per polymersome of approximately 35. It was demonstrated that the uptake of Tf-PO by bEnd.3 was mainly through a clathrin mediated energy-dependent endocytosis. Both the Golgi apparatus and lysosomes are involved in intracellular transport of Tf-PO. Thirty minutes after a 50 mg/kg dose of Tf-PO or PO was injected into rats via the tail vein, fluorescent microscopy of brain coronal sections showed a higher accumulation of Tf-PO than PO in the cerebral cortex, the periventricular region of the lateral ventricle and the third ventricle. The brain delivery results proved that the blood–brain barrier (BBB) permeability surface area product (PS) and the percentage of injected dose per gram of brain (%ID/g brain) for Tf-PO were increased to 2.8-fold and 2.3-fold, respectively, as compared with those for PO. These results indicate that Tf-PO is a promising brain delivery carrier.
Keywords: Biodegradable polymersomes; Transferrin; Brain delivery; Cellular internalization; Brain–blood barrier (BBB);
Preparation and antitumor study of camptothecin nanocrystals by Hua Zhang; Christin P. Hollis; Qiang Zhang; Tonglei Li (293-300).
Camptothecin (CPT) is a potent, broad spectrum antitumor agent that inhibits the activity of DNA topoisomerase I. Due to its poor solubility and stability and consequent delivery challenges, its clinical use is nevertheless limited. We aim to use nanocrystal formulation as a way to circumvent the difficult solubilization practice. Specifically, camptothecin nanocrystals were prepared with a sonication–precipitation method without additional stabilizing surfactants. Particle characteristics, cellular cytotoxicity, and animal antitumor effect were examined. CPT nanocrystals were tested to be more potent to MCF-7 cells than CPT solution in vitro. When tested in MCF-7 xenografted BALB/c mice, the CPT nanocrystals exhibited significant suppression of tumor growth. The drug concentration in the tumor was five times more at 24 h by using the nanocrystal treatment than by using the drug salt solution. Storage stability study indicated that the nanocrystals were stable for at least six months. Overall, CPT nanocrystals were considered to be potentially feasible to overcome formulation challenges for drug delivery and to be used in clinic.
Keywords: Camptothecin; Nanocrystals; Nanosuspension; MCF-7; Antitumor efficacy;
Differential scanning calorimetry studies on sunscreen loaded solid lipid nanoparticles prepared by the phase inversion temperature method by L. Montenegro; M.G. Sarpietro; S. Ottimo; G. Puglisi; F. Castelli (301-306).
Solid lipid nanoparticles (SLN) are regarded as interesting carriers to improve sunscreens’ safety and effectiveness. In this work, surfactant effects on the physico-chemical properties of SLN loading two of the most widely used UV-filters, octylmethoxycinnamate (OMC) and butylmethoxydibenzoylmethane (BMBM), were evaluated and the interactions between SLN components and loaded UV-filters were investigated by differential scanning calorimetry (DSC). All the SLN showed a mean size ranging from 30 to 95 nm, and a single peak in size distribution. The use of isoceth-20 or oleth-20 as primary surfactants did not provide SLN with suitable physico-chemical properties since: (a) OMC loaded SLN proved unstable; (b) BMBM could not be loaded. OMC or BMBM loaded SLN prepared using ceteth-20 as primary surfactant were stable but their loading capacity lowered when both sunscreens were loaded simultaneously. DSC analyses showed that OMC distributed inside the SLN and caused a decrease of the lipid matrix molecules cooperativity while BMBM did not affect SLN calorimetric behaviour. When OMC and BMBM were loaded together into these SLN, an interaction between BMBM and OMC occurred. These results suggest that the interactions between sunscreens and between sunscreens and SLN components deserve further investigation to evaluate their effect on UV-filter-loaded SLN effectiveness.
Keywords: Solid lipid nanoparticles; Sunscreen; Differential scanning calorimetry; Phase inversion temperature; Non-ionic surfactants;
Comminution of ibuprofen to produce nano-particles for rapid dissolution by S. Plakkot; M. de Matas; P. York; M. Saunders; B. Sulaiman (307-314).
A critical problem associated with poorly soluble drugs is low and variable bioavailability derived from slow dissolution and erratic absorption. The preparation of nano-formulations has been identified as an approach to enhance the rate and extent of drug absorption for compounds demonstrating limited aqueous solubility. A new technology for the production of nano-particles using high speed, high efficiency processes that can rapidly generate nano-particles with rapid dissolution rate has been developed. Size reduction of a low melting ductile model compound was achieved in periods less than 1 h. Particle size reduction of ibuprofen using this methodology resulted in production of crystalline particles with average diameter of approximately 270 nm. Physical stability studies showed that the nano-suspension remained homogeneous with slight increases in mean particle size, when stored at room temperature and under refrigerated storage conditions 2–8 °C for up to 2 days. Powder containing crystalline drug was prepared by spray-drying ibuprofen nano-suspensions with mannitol dissolved in the aqueous phase. Dissolution studies showed similar release rates for the nano-suspension and powder which were markedly improved compared to a commercially available drug product. Ibuprofen nano-particles could be produced rapidly with smaller sizes achieved at higher suspension concentrations. Particles produced in water with stabilisers demonstrated greatest physical stability, whilst rapid dissolution was observed for the nano-particles isolated in powder form.
Keywords: Ibuprofen; Comminution; Nano-suspension; Nano-particles; Spray drying; Dissolution;
Gold nanorod mediated plasmonic photothermal therapy: A tool to enhance macromolecular delivery by Adam J. Gormley; Khaled Greish; Abhijit Ray; Ryan Robinson; Joshua A. Gustafson; Hamidreza Ghandehari (315-318).
Plasmonic photothermal therapy (PPTT) with gold nanostructures has been used to generate significant heat within tumors to ablate vasculature. Here we report the use of gold nanorod (GNR) mediated PPTT to induce moderate hyperthermia as a tool to enhance the delivery of macromolecules. GNRs were injected intravenously in a mouse sarcoma (S-180) tumor model. After 24 h Evans blue dye (EBD) was injected and the right tumor was radiated with a laser diode for 10 min. EBD content in the right and left tumors were extracted in formamide, measured spectrophotometrically and expressed as a thermal enhancement ratio (TER). Enhanced delivery of EBD was observed (up to 1.8-fold) when tumor temperatures reached 43 °C or 46 °C. No statistical difference was observed between tumors at these two temperatures, though significant hemorrhage was observed in tumors and surrounding areas receiving the higher thermal dose (46 °C). These results indicate that tumor directed PPTT may be used to induce moderate hyperthermia and therefore selectively increase the delivery of macromolecules with therapeutic anticancer drugs.
Keywords: Gold nanorods; Hyperthermia; Enhanced permeability and retention (EPR); Plasmonic photothermal therapy (PPTT); Permeability;