International Journal of Pharmaceutics (v.464, #1-2)
EDITORIAL BOARD (iii).
In vitro dissolution enhancement of micronized l-nimodipine by antisolvent re-crystallization from its crystal form H by Yuangang Zu; Na Li; Xiuhua Zhao; Yong Li; Yulong Ge; Weiguo Wang; Kunlun Wang; Ying Liu (1-9).
In order to enhance solubility and dissolution rate in water, micronized l-nimodipine (NMD) has been successfully prepared by antisolvent re-crystallization process using acetone as solvent and deionized water as antisolvent. The effects of five experimental parameters on the mean particle size (MPS) of NMD nanosuspension were investigated. It was found that the MPS of NMD nanosuspension decreased significantly when the concentration of NMD–acetone solution increased from 50 to 150 mg/mL along with the increase of volume ratio of antisolvent to solvent from 1 to 3, and then increased slightly with the following increase of them. By contrast, the MPS decreased with the increased feed rate of NMD–acetone solution and the amount of surfactant, from 1 to 3 mL/min and 0.025% to 0.2%, respectively. Thereafter, the MPS did not show any obvious change. The precipitation temperature had no significant effects on MPS. The optimum micronization conditions were determined as follows: NMD–acetone solution concentration of 150 mg/mL, the volume ratio of antisolvent to solvent of 3, the flow rate of NMD–acetone solution of 9 mL/min, the preparation temperature of 15 °C and the amount of the surfactant of 0.2%. Under optimum conditions, micronized NMD with a MPS of 708.3 nm was obtained. The micronized product was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatography–mass spectrometry (LC–MS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermo gravimetric (TG), to verify the influences of micronization process on the final product. The results showed that the chemical structure of micronized NMD was not changed, but the crystalline structure had undergone transition during precipitation, which changed from form H into L. The dissolution test showed that micronized l-NMD exhibited enhanced dissolution rate and solubility of 5.22 folds compared to raw H-NMD. These results suggested that micronized l-NMD may have potential value to become a new oral NMD formulation with high bioavailability.
Keywords: Nimodipine; Antisolvent re-crystallization; Crystal transition; Dissolution; Nimodipine (PubChem CID: 4497);
Formulation and in vitro evaluation of size expanding gastro-retentive systems of levofloxacin hemihydrate by Sally A. El-Zahaby; Abeer A. Kassem; Amal H. El-Kamel (10-18).
Size increasing (plug-type) levofloxacin hemihydrate (LVF) tablets for eradication of Helicobacter pylori (H. pylori) were prepared using in situ gel forming polymers including: gellan gum, sodium alginate, pectin and xanthan gum. Effect of cross-linkers: calcium and aluminum chloride, on the drug release was also studied. The prepared tablets were evaluated for their physicochemical parameters: weight variation, thickness, friability, hardness, drug content, water uptake and in vitro drug release. The optimized formula was subjected to further studies such as radial swelling test, FT-IR and DSC. Results revealed that LVF release depends not only on the nature of the matrix but also on the type of cross linker used to form this polymeric matrix. The addition of either calcium chloride or aluminum chloride, as cross-linkers, to gellan gum formulations significantly decreased drug release. Other polymers’ formulations resulted in increased drug release upon addition of the same cross-linkers. The formula containing xanthan gum without any cross linker showed the most sustained LVF release with an increase in diameter with time, thus acting as a plug-type dosage form. IR spectra and DSC thermograms of LVF, xanthan gum, and a physical mixture of both, indicated that there was no interaction between the drug and the polymer and confirmed the drug stability.
Keywords: Gastroretentive; Levofloxacin; Plug-type; Fluoroquinolone; Cross-linker;
Development and evaluation of a tacrolimus cream formulation using a binary solvent system by Masayuki Yamanaka; Shoji Yokota; Yasunori Iwao; Shuji Noguchi; Shigeru Itai (19-26).
We developed an oil/water-type tacrolimus (FK506) cream formulation as an alternative to Protopic ointment for atopic dermatitis treatment. We determined the effects of solvents used in topical preparations on FK506 solubility and stability, and evaluated FK506 transdermal absorption into rat skin from solutions, emulsions, and creams. Screening indicated that diethyl sebacate (DES), isopropyl myristate (IPM), propylene glycol (PG), and oleyl alcohol (OA) were adequate FK506 solvents. When FK506 solutions prepared using these solvents were transdermally administered, AUC0–24 values for DES and IPM were higher than or similar to that for 0.1% Protopic ointment. The AUC0–24 values for PG and OA were low, so these solvents did not enhance absorption. The residual ratios of FK506 in DES and IPM solutions after incubation at 70 °C for 9 d were 95.6% and 88.6%, respectively, so DES and IPM were chosen for emulsion preparation. When the emulsions were transdermally administered, the IPM emulsion AUC0–24 values increased 4.6-fold; DES emulsions did not show high transdermal absorption, but showed sustained characteristics. A cream formulation prepared by mixture of IPM and DES also showed high absorption and transdermal absorption increased with increasing IPM ratio. We developed an FK506 cream formulation with a controllable transdermal absorption rate by manipulating the IPM:DES ratio.
Keywords: Tacrolimus; Cream; Surfactant; Emulsion; Binary solvent;
Anatomy of plasmid DNAs with anti-silencing elements by Genki N. Kanda; Shiho Miyamoto; Miwako Kobayashi; Ichiro Matsuoka; Hideyoshi Harashima; Hiroyuki Kamiya (27-33).
The transience of transgene expression is a major obstacle in the development of nonviral vectors. The CpG-free and pLIVE plasmids reportedly achieve long-term transgene expression in mouse liver. In this work, the anti-silencing elements within these plasmids were studied. The effects of plasmid that was being silenced on transgene expression from the CpG-free plasmid and those of transgene expression at early time points on silencing were also examined. The results suggested that the backbone sequence of the CpG-free plasmid and the 3′ untranslated region of the albumin gene of the pLIVE plasmid contribute to durable expression. In addition, no influence of the silencing of another plasmid on the duration of CpG-free plasmid expression or of transgene expression at early time points on silencing was detected.
Keywords: Transgene expression; Nonviral vector; Anti-silencing element; Hydrodynamics-based method;
Formulation parameters of crystalline nanosuspensions on spray drying processing: A DoE approach by Sumit Kumar; Xiaoming Xu; Rajeev Gokhale; Diane J. Burgess (34-45).
Nanocrystalline suspensions offer a promising approach to improve dissolution of BCS class II/IV compounds. Spray drying was utilized as a downstream process to improve the physical and chemical stability of dried nanocrystals. The effect of nanocrystalline suspension formulation variables on spray-drying processing was investigated. Naproxen and indomethacin nanocrystalline formulations were formulated with either Dowfax 2A1 (small molecule) or HPMC E15 (high molecular weight polymer) and spray drying was performed. A DoE approach was utilized to understand the effect of critical formulation variables, i.e. type of stabilizer, type of drug, ratio of drug-to-stabilizer and drug concentration. The powders were analyzed for particle size, moisture content, powder X-ray diffraction and dissolution. A dialysis sac adapter for USP apparatus II was developed which provided good discrimination between aggregated and non-aggregated formulations. Nanocrystal aggregation was dependent on the drug-to-stabilizer ratio. The glass transition temperature and the charge effect played a dominant role on spray-dried powder yield. Those formulations with low drug-to-excipient ratios were less aggregating and showed faster dissolution compared to those formulations with high drug-to-excipient ratios. All stable (less aggregated) formulations were subjected to accelerated storage stability testing. The Flory–Huggins interaction parameter (between drug and excipients) correlated with the spray-dried nanocrystal formulations stability.
Keywords: Nanosuspension; Spray drying; Re-dispersion; Nanocrystalline; DoE;
Pharmaceutical characterization and thermodynamic stability assessment of a colloidal iron drug product: Iron sucrose by Rakhi B. Shah; Yongsheng Yang; Mansoor A. Khan; Andre Raw; Lawrence X. Yu; Patrick J. Faustino (46-52).
Molecular weight stability of iron sucrose under accelerated (40 °C) and extreme (90 °C) stress conditions monitored by gel permeation chromatogram (GPC): 0 day (▪), 1 day (▪), 3 day (▪), and 7 day (▪) exposures.The study objective was to evaluate the thermodynamic stability of iron sucrose complexes as determined by molecular weight (m.w.) changes. The first part of the study focused on the effect of thermal stress, pH, electrolyte or excipient dilution on the stability of a colloidal iron drug product. Part two focused on the physical and chemical evaluation of the colloidal nature of iron sucrose using a series of characterization experiments: ultracentrifugation, dialysis, particle size, zeta potential, and osmotic pressure analysis. A validated Taguchi-optimized high performance gel permeation chromatography method was used for m.w. determinations. Results indicate m.w. of the iron sucrose complex remained unchanged after excipient dilution, ultracentrifugation, dialysis, and electrolyte dilution. Electrolyte dilution studies indicated the lyophilic nature of the iron sucrose colloid with a particle size of 10 nm and zeta potential of 0 mV. The complex deformed at low pH and reformed back at the formulation pH. The complex is stable under mild-to-moderate temperature <50 °C but aggregates following prolonged exposure to high temperatures >70 °C. In conclusion, the resistance of the complex to breakdown by electrolytic conditions, excipient dilution, ultracentrifugation and the reversible complexation after alteration of formulation pH suggest iron sucrose is a lyophilic colloid in nature and lyophilic colloidals are thermodynamically stable.
Keywords: Colloid; Formulation; Nanoparticles; Stability; Chromatography; Thermodynamic stability;
An approach to engineer paracetamol crystals by antisolvent crystallization technique in presence of various additives for direct compression by Waseem Kaialy; Hassan Larhrib; Brian Chikwanha; Saeed Shojaee; Ali Nokhodchi (53-64).
Paracetamol is a popular over-the-counter analgesic and a challenging model drug due to its poor technological and biopharmaceutical properties such as flowability, compressibility, compactibility and wettability. This work was aimed to alter the crystal habit of paracetamol from elongated to polyhedral-angular via particle engineering whilst maintaining the stable polymorphic form (form I: monoclinic form). The engineered paracetamol crystals obtained in the present investigation showed better technological and biopharmaceutical properties in comparison to the commercial paracetamol. Engineered paracetamol crystals were obtained using antisolvent crystallization technique in the presence of various concentrations (0.1, 0.5 and 1%, w/w) of additives, namely, polyvinyl alcohol (PVA), Avicel PH 102 (microcrystalline cellulose), Brij 58, methylcellulose (MC) and polyethylene glycol having different molecular weights (PEGs 1500, 6000 and 8000). Paracetamols crystallized in the presence of Avicel (or physically mixed with Avicel), Brij 58 and PEG 6000 demonstrated the best compactibility over a range of compaction pressures. Brij-crystallized paracetamol provided the fastest dissolution rate among all the paracetamol batches. Paracetamols crystallized in the presence of PVA or Avicel, or physically mixed with Avicel demonstrated a reduced degree of crystallinity in comparison to the other paracetamols. This study showed that the type, the grade and the concentration of additives could influence the physical stability such as flow, crystallinity and polymorphic transformation of paracetamol, the technological and biopharmaceutical properties of paracetamol. Stable polymorphic form of paracetamol with optimal tableting characteristics can be achieved through particle engineering.
Keywords: Particle engineering; Antisolvent crystallization; Paracetamol; Additives; Compactibility; Crystal habit;
Hot-melt co-extrusion for the production of fixed-dose combination products with a controlled release ethylcellulose matrix core by A.-K. Vynckier; L. Dierickx; L. Saerens; J. Voorspoels; Y. Gonnissen; T. De Beer; C. Vervaet; J.P. Remon (65-74).
In this study, hot-melt co-extrusion was evaluated as a technique for the production of fixed-dose combination products, using ethylcellulose as a core matrix former to control the release of metoprolol tartrate and a polyethylene oxide-based coat formulation to obtain immediate release of hydrochlorothiazide. By lowering the concentration of the hydrophilic additive polyethylene oxide in the plasticized ethylcellulose matrix or by lowering the drug load, the in vitro metoprolol tartrate release from the core was substantially sustained. The in vitro release of hydrochlorothiazide from the polyethylene oxide/polyethylene glycol coat was completed within 45 min for all formulations. Tensile testing of the core/coat mini-matrices revealed an adequate adhesion between the two layers. Raman mapping showed no migration of active substances. Solid state characterization indicated that the crystalline state of metoprolol tartrate was not affected by thermal processing via hot-melt extrusion, while hydrochlorothiazide was amorphous in the coat. These solid state characteristics were confirmed during the stability study. Considering the bioavailability of metoprolol tartrate after oral administration to dogs, the different co-extruded formulations offered a range of sustained release characteristics. Moreover, high metoprolol tartrate plasma concentrations were reached in dogs allowing the administered dose to be halved.
Keywords: Co-extrusion; Hot-melt extrusion; Fixed-dose combination product; Sustained release; Immediate release; Matrix;
Transdermal delivery of flurbiprofen from surfactant-based vesicles: Particle characterization and the effect of water on in vitro transport by Tomonobu Uchino; Yuiko Matsumoto; Akiko Murata; Toshihiko Oka; Yasunori Miyazaki; Yoshiyuki Kagawa (75-84).
Flurbiprofen permeation across YMP skin decreased by phase transition with water evaporation.Flurbiprofen loaded rigid and elastic vesicles comprising the bilayer-forming surfactant sucrose-ester laurate were prepared by the film rehydration and extrusion method. The charge-inducing agent sodium dodecyl sulfate, and the micelle-forming surfactants, sorbitan monolaurate, polyethylene glycol monolaurate, and polysorbate 20, were used to enhance elasticity. Vesicle formulations were evaluated for size, zeta potential, 1H and 19F nuclear magnetic resonance (NMR) spectra, and in vitro skin permeation across Yucatan micropig (YMP) skin. Vesicle formulations were stable for 2 weeks and their mean sizes were 95–135 nm. NMR spectroscopy showed that flurbiprofen molecular mobility was restricted by interaction with vesicle components because of entrapment in vesicle bilayers. Moreover, sorbitan monolaurate-containing vesicles strongly retained flurbiprofen molecules. After non-occlusive application to YMP skin, flurbiprofen transport from all vesicle formulations was superior to that of flurbiprofen alone and remarkably decreased after water vaporization. Polarization microscopy and small-angle X-ray diffraction analysis showed that the vesicle formulation was transferred to liquid crystalline state. Suppression of vesicle transition to the liquid crystalline state was observed with applications of both large quantities and diluted samples. The presence of water in the formulations was associated with maintenance of the vesicle structure and greater flurbiprofen transport across YMP skin.
Keywords: Surfactant-based vesicle; Skin permeation; 1H NMR; 19F NMR; Flurbiprofen; Liquid crystal;
A non-binary biopharmaceutical classification of drugs: The ABΓ system by Panos Macheras; Vangelis Karalis (85-90).
The purpose of the present work is to develop a non-binary biopharmaceutical classification system the so called ABΓ system. The original mathematical model used for the development of BCS, appropriately modified, was applied to estimate the limiting values of drug solubility and permeability when the fraction of dose absorbed, Fa, was 0.90 or 0.20. The ABΓ system is based on the fraction of dose absorbed and relies on permeability, solubility plane. The first category (A, alpha) includes drugs with Fa ≥ 0.90, whereas the B (beta) category consists of drugs with Fa ≤ 0.20. The area lying between the two boundaries of A and B defines the third category (gamma), Γ, (0.20 < Fa < 0.90). For comparative purposes, the BCS classes I–IV were co-plotted together with the ABΓ system. Most of the BCS classes II and III are included in category Γ which mainly consists of drugs with properties like moderate or low solubility and permeability. Due to the dynamic character of dissolution and uptake processes, category A is expanded toward BCS Class II. The ABΓ system allows the classification of all compounds into three categories (A, B, Γ) in terms of the fraction of dose absorbed.
Keywords: Non-binary BCS; Solubility; Permeability; Dose; Simulations; Fraction of dose absorbed;
Bladder tissue permeability and transport modelling of intravesical alum, lidocaine hydrochloride, methylprednisolone hemisuccinate and mitomycin C by Céline Moch; Damien Salmon; Laura Rodríguez Armesto; Marc Colombel; Christine Pivot; Fabrice Pirot (91-103).
The aims of this study were to assess the tissue permeability of the bladder and to characterize the transport of four drugs displaying different physico-chemical properties and commonly used in intravesical delivery, through porcine bladder. The transport of aluminium through porcine bladder was assessed by using a vertical static diffusion cell. Lidocaine hydrochloride, methylprednisolone hemisuccinate and mitomycin C were tested by using three different experimental setups, including vertical static diffusion cell, microdialyseur and lab-patented device. Penetration results on different experimental setups were homogenous suggesting dependency on physico-chemical characteristics of drug and subsequent interaction with bladder wall structure. Oppositely, permeation varied consistently with experimental setup characteristics (i.e., permeation surface, receptor fluid volume and hydrodynamic). Mathematical modelling of drug transport through bladder wall is proposed considering scarce literature on this route of administration. Practical outcome of this study could drive compounding optimization towards improvement of safety and efficacy in patient undergoing intravesical administration.
Keywords: Intravesical drug delivery; Fickian model; Bladder; Permeability;
Investigating permeability related hurdles in oral delivery of 11-keto-β-boswellic acid by Pravin Bagul; Kailas S. Khomane; Arvind K. Bansal (104-110).
11-Keto-β-boswellic acid (KBA) is an important and potent boswellic acids responsible for anti-inflammatory action of Boswellia extract. However, its pharmaceutical development has been severely limited by its poor oral bioavailability. The present work aims to investigate the permeability related hurdles in oral delivery of KBA. Gastrointestinal stability, gastrointestinal metabolism, adsorption–desorption kinetics and Caco-2 permeability studies have been carried out. KBA was found poorly permeable with P app value of 2.85 ± 0.14 × 10−6 cm/s. Higher absorptive transport indicated role of carrier mediated transport. Moreover, KBA transport across monolayer showed saturation kinetics at higher concentrations. KBA exposed to 1α,25-(OH)2 vitamin D3 treated cell monolayer showed the lowest P app value of 2.01 × 10−6 ± 0.02 × 10−6 cm/s indicating role of CYP3A4 mediated metabolism during KBA transport. Metabolic stability experiments in jejunum S9 fractions further confirmed this. KBA was found unstable in simulated gastrointestinal fluids and also got accumulated in the enterocytes. Sorption and desorption kinetic studies using Caco-2 cells further confirmed accumulation of KBA inside the enterocytes. KBA also showed pH dependent permeability with higher flux at gradient pH condition of pH 6.5 at apical and 7.4 at basolateral. Taken as whole, the major permeability related hurdles that hampered oral bioavailability of KBA included its gastrointestinal instability, CYP3A4 mediated intestinal metabolism, accumulation within the enterocytes and saturable kinetics. The present investigation may help in designing novel drug delivery system for KBA.
Keywords: Boswellic acids; Oral bioavailability; Caco-2 cells; Intestinal absorption; Permeability hurdles; Gastrointestinal metabolism;
Rational design of a series of novel amphipathic cell-penetrating peptides by Jakob Regberg; Artita Srimanee; Mikael Erlandsson; Rannar Sillard; Dimitar A. Dobchev; Mati Karelson; Ülo Langel (111-116).
A series of novel, amphipathic cell-penetrating peptides was developed based on a combination of the model amphipathic peptide sequence and modifications based on the strategies developed for PepFect and NickFect peptides. The aim was to study the role of amphipathicity for peptide uptake and to investigate if the modifications developed for PepFect peptides could be used to improve the uptake of another class of cell-penetrating peptides. The peptides were synthesized by solid phase peptide synthesis and characterized by circular dichroism spectroscopy. Non-covalent peptide–plasmid complexes were formed by co-incubation of the peptides and plasmids in water solution. The complexes were characterized by dynamic light scattering and cellular uptake of the complexes was studied in a luciferase-based plasmid transfection assay. A quantitative structure–activity relationship (QSAR) model of cellular uptake was developed using descriptors including hydrogen bonding, peptide charge and positions of nitrogen atoms.The peptides were found to be non-toxic and could efficiently transfect cells with plasmid DNA. Cellular uptake data was correlated to QSAR predictions and the predicted biological effects obtained from the model correlated well with experimental data. The QSAR model could improve the understanding of structural requirements for cell penetration, or could potentially be used to predict more efficient cell-penetrating peptides.
Keywords: Cell-penetrating peptide; Model amphipathic peptide; Plasmid transfection; Structure–activity; QSAR;
Emulsion-based colloidal nanosystems for oral delivery of doxorubicin: Improved intestinal paracellular absorption and alleviated cardiotoxicity by Ji-Eon Kim; In-Soo Yoon; Hyun-Jong Cho; Dong-Hwan Kim; Young-Hee Choi; Dae-Duk Kim (117-126).
We have previously reported that the limited intestinal absorption via the paracellular pathway may be the primary cause of the low oral bioavailability of doxorubicin (DOX). In this study, we have formulated medium chain glycerides-based colloidal nanosystems to enhance the intestinal paracellular absorption of DOX and reduce its cardiotoxicity. The DOX formulations prepared by the construction of pseudo-ternary phase diagram were characterized in terms of their droplet size distribution, viscosity, drug loading, and drug release. Further evaluation was conducted by an in vitro Caco-2 transport study as well as in situ/in vivo intestinal absorption, bioavailability and toxicity studies. Compared with DOX solution, these formulations enhanced the absorptive transport of DOX across Caco-2 cell monolayers at least partly due to the paracellular-enhancing effects of their lipidic components. Moreover, the in situ intestinal absorption and in vivo oral bioavailability of DOX in rats were markedly enhanced. In addition, no discernible damage was observed in the rat jejunum after oral administration of these DOX formulations while the cardiac toxicity was significantly reduced when compared with intravenous DOX solution. Taken together, the medium chain glycerides-based colloidal nanosystems prepared in this study represent a potentially effective oral delivery system for DOX.
Keywords: Colloidal nanosystem; Medium chain glyceride; Doxorubicin; Intestinal paracellular absorption; Cardiotoxicity; Oral delivery;
Polyethylene glycol-modified arachidyl chitosan-based nanoparticles for prolonged blood circulation of doxorubicin by Ubonvan Termsarasab; In-Soo Yoon; Ju-Hwan Park; Hyun Tae Moon; Hyun-Jong Cho; Dae-Duk Kim (127-134).
Doxorubicin (DOX)-loaded nanoparticles based on polyethylene glycol-conjugated chitosan oligosaccharide-arachidic acid (CSOAA-PEG) were explored for potential application to leukemia therapy. PEG was conjugated with CSOAA backbone via amide bond formation and the final product was verified by 1H NMR analysis. Using the synthesized CSOAA-PEG, nanoparticles having characteristics of a 166-nm mean diameter, positive zeta potential, and spherical shape were produced for the delivery of DOX. The mean diameter of CSOAA-PEG nanoparticles in the serum solution (50% fetal bovine serum) remained relatively constant over 72 h as compared with CSOAA nanoparticles (changes of 20.92% and 223.16%, respectively). The sustained release pattern of DOX from CSOAA-PEG nanoparticles was displayed at physiological pH, and the release rate increased under the acidic pH conditions. The cytotoxicity of the CSOAA-PEG conjugate was negligible in human leukemia cells (K562) at the concentrations tested (∼100 μg/ml). The uptake rate of DOX from the nanoparticles by K562 cells was higher than that from the solution. Judging from the results of pharmacokinetic studies in rats, in vivo clearance rate of DOX from the CSOAA-PEG nanoparticle group was slower than other groups, subsequently extending the circulation period. The PEGylated CSOAA-based nanoparticles could represent an effective nano-sized delivery system for DOX which has been used for the treatment of blood malignancies.
Keywords: Arachidyl chitosan; Polyethylene glycol; Doxorubicin; Leukemia; Prolonged blood circulation;
Marked effects of combined TPGS and PVA emulsifiers in the fabrication of etoposide-loaded PLGA-PEG nanoparticles: In vitro and in vivo evaluation by Roonak Saadati; Simin Dadashzadeh (135-144).
Using TPGS in combination with PVA as an emulsifier in fabrication of etoposide (ET) loaded nanoparticles (NPs) markedly increased encapsulation efficiency, sustained drug release and resulted in nanoparticles with noticeable sustainable in vivo disposition.The purpose of this study was to investigate the effect of d-alpha tocopheryl polyethylene glycol 1000 succinate (TPGS) alone or in combination with other emulsifiers in the fabrication of etoposide-loaded PLGA-PEG nanoparticles for in vivo applications.Nanoparticles were prepared by nanoprecipitation or single-emulsion solvent evaporation method using TPGS alone or in combination with other surfactants. These nanoparticles were fully characterized by different techniques. For nanoprecipitation preparations, by adding 0.1% TPGS to polyvinyl alcohol in the aqueous phase, encapsulation efficiency markedly increased (up to 82%); moreover, drug release was readily controlled up to 3 days. Regarding emulsion solvent evaporation method, the highest encapsulation efficiency was obtained for nanoparticles emulsified with polyvinyl alcohol or TPGS; however, the burst release was high. When the combination of TPGS and polyvinyl alcohol was applied a marked increase in encapsulation efficiency (∼90%) was observed and the drug release was extended to more than one week.Pharmacokinetic measurements showed that the optimum formulation generated 14.4 times higher AUC and lasted 5.1 times longer when compared to free drug. Overall, using TPGS in combination with polyvinyl alcohol as an emulsifier in preparing etoposide loaded PLGA-PEG nanoparticles markedly increased the encapsulation efficiency, sustained drug release and resulted in nanoparticles with noticeable sustainable in vivo disposition.
Keywords: PLGA-PEG; TPGS; Nanoparticles; Etoposide; Dual emulsifiers; Pharmacokinetics;
The effects of heat on skin barrier function and in vivo dermal absorption by Gabriela Oliveira; Jesse C. Leverett; Mandana Emamzadeh; Majella E. Lane (145-151).
Enhanced delivery of ingredients across the stratum corneum (SC) is of great interest for improving the efficacy of topically applied formulations. Various methods for improving dermal penetration have been reported including galvanic devices and micro-needles. From a safety perspective it is important that such approaches do not compromise SC barrier function. This study investigates the influence of topically applied heat in vivo on the dermal uptake and penetration of a model active, allantoin from gel and lotion formulations.A custom designed device was used to deliver 42 °C for 30 s daily to human subjects after application of two formulations containing allantoin. The results were compared with sites treated with formulations containing no active and no heat, and a control site. In addition to penetration of allantoin, the integrity of the SC was monitored using trans-epidermal water loss (TEWL) measurements.The results showed that just 30 s of 42 °C topically applied heat was enough to cause significantly more penetration of allantoin from the lotion formulation compared with no application of heat. TEWL data indicated that the integrity of the skin was not compromised by the treatment. However, the application of heat did not promote enhanced penetration of the active from the gel formulation. Vehicle composition is therefore an important factor when considering thermal enhancement strategies for targeting actives to the skin.
Keywords: Heat; Skin absorption; Barrier properties; In vivo; Allantoin;
Can metabolic impairments in experimental diabetes be cured with poly(amido)amine (PAMAM) G4 dendrimers? – In the search for minimizing of the adverse effects of PAMAM administration by Magdalena Labieniec-Watala; Tomasz Przygodzki; Katarina Sebekova; Cezary Watala (152-167).
The extents of hypoglycaemizing (glycaemia) and anti-glycation (HbA1c, AGEs, AOPP) effects of PAMAM G4, administered to streptozotocin-diabetic rats, depended on the route of dendrimer administration: intraperitoneal (IP), intragastrical (IG) or subcutaneous (SC).Poly(amido)amine (PAMAM) G4 dendrimers, given intraperitoneally to diabetic rats, have been reported to scavenge excessive blood glucose and minimize the effects of hyperglycaemia, however, at the cost of reduced survival. This paper is the first to compare the effectiveness of three different routes of PAMAM G4 administration with regard to minimizing the adverse effects of hyperglycaemia in rats. Hence, the aim of the study is to identify the most effective and the least harmful method of dendrimer administration. Control and streptozotocin-diabetic Sprague-Dawley rats were exposed to PAMAM G4 (0.5 μmol/kg b.w.) for 60 days, administered intraperitoneally, intragastrically or subcutaneously.Intraperitoneal and subcutaneous administration of PAMAM G4 was found to be most effective in suppressing the long-term markers of hyperglycaemia, while the intragastric route appeared the least effective. Otherwise, the greatest incidence of adverse effects was associated with intraperitoneal and the lowest with subcutaneous delivery. Harmful effects of intragastrical administration were much lower compared to intraperitoneal route, but at the cost of reduced hypoglycaemizing potential. Otherwise, subcutaneous injection represents the best compromise of moderate PAMAM dendrimer toxicity and effective reduction in the markers of long-term severe hyperglycaemia in chronic experimental diabetes.
Keywords: PAMAM dendrimers; Streptozotocin-diabetes; Survival; Diabetic hyperglycaemia markers; Sprague-Dawley rats; In vivo study;
Image-based analysis of the size- and time-dependent penetration of polymeric micelles in multicellular tumor spheroids and tumor xenografts by Andrew S. Mikhail; Sina Eetezadi; Sandra N. Ekdawi; James Stewart; Christine Allen (168-177).
While the heightened tumor accumulation of systemically administered nanomedicines relative to conventional chemotherapeutic agents has been well established, corresponding improvements in therapeutic efficacy have often been incommensurate. This observation may be attributed to the limited exposure of cancer cells to therapy due to the heterogeneous intratumoral distribution and poor interstitial penetration of nanoparticle-based drug delivery systems. In the present work, the spatio-temporal distribution of block copolymer micelles (BCMs) of different sizes was evaluated in multicellular tumor spheroids (MCTS) and tumor xenografts originating from human cervical (HeLa) and colon (HT29) cancer cells using image-based, computational techniques. Micelle penetration was found to depend on nanoparticle size, time as well as tumor and spheroid cell line. Moreover, spheroids demonstrated the capacity to predict relative trends in nanoparticle interstitial transport in tumor xenografts. Overall, techniques are presented for the assessment of nanoparticle distribution in spheroids and xenografts and used to evaluate the influence of micelle size and cell-line specific tissue properties on micelle interstitial penetration.
Keywords: Nanoparticle; Block copolymer micelle; Spheroid; Tumor penetration; Nanomedicine; Cancer;
Polyethylene glycol-phosphatidylethanolamine (PEG-PE)/vitamin E micelles for co-delivery of paclitaxel and curcumin to overcome multi-drug resistance in ovarian cancer by Abraham H. Abouzeid; Niravkumar R. Patel; Vladimir P. Torchilin (178-184).
The therapeutic potential of mixed micelles, made of PEG-PE and vitamin E co-loaded with curcumin and paclitaxel, was investigated against SK-OV-3 human ovarian adenocarcinoma along with its multi-drug resistant version SK-OV-3-paclitaxel-resistant (TR) cells in vitro and in vivo. The addition of curcumin at various concentrations did not significantly enhance the cytotoxicity of paclitaxel against SK-OV-3 in vitro. However, a clear synergistic effect was observed with the combination treatment against SK-OV-3TR in vitro. In vivo, this combination treatment produced a three-fold tumor inhibition with each of these cell lines. Our results indicate that such co-loaded mixed micelles could have significant clinical advantages for the treatment of resistant ovarian cancer.
Keywords: Curcumin; Nuclear factor-kappa B (NF-κB); Mixed micelles; Multi-drug resistance; Combination therapy; Ovarian cancer;
Starch-coated magnetic liposomes as an inhalable carrier for accumulation of fasudil in the pulmonary vasculature by Kamrun Nahar; Shahriar Absar; Brijeshkumar Patel; Fakhrul Ahsan (185-195).
In this study, we tested the feasibility of magnetic liposomes as a carrier for pulmonary preferential accumulation of fasudil, an investigational drug for the treatment of pulmonary arterial hypertension (PAH). To develop an optimal inhalable formulation, various magnetic liposomes were prepared and characterized for physicochemical properties, storage stability and in vitro release profiles. Select formulations were evaluated for uptake by pulmonary arterial smooth muscle cells (PASMCs) – target cells – using fluorescence microscopy and HPLC. The efficacy of the magnetic liposomes in reducing hyperplasia was tested in 5-HT-induced proliferated PASMCs. The drug absorption profiles upon intratracheal administration were monitored in healthy rats. Optimized spherical liposomes – with mean size of 170 nm, zeta potential of −35 mV and entrapment efficiency of 85% – exhibited an 80% cumulative drug release over 120 h. Fluorescence microscopic study revealed an enhanced uptake of liposomes by PASMCs under an applied magnetic field: the uptake was 3-fold greater compared with that observed in the absence of magnetic field. PASMC proliferation was reduced by 40% under the influence of the magnetic field. Optimized liposomes appeared to be safe when incubated with PASMCs and bronchial epithelial cells. Compared with plain fasudil, intratracheal magnetic liposomes containing fasudil extended the half-life and area under the curve by 27- and 14-fold, respectively. Magnetic-liposomes could be a viable delivery system for site-specific treatment of PAH.
Keywords: Magnetic liposomes; Pulmonary delivery; Pulmonary arterial hypertension (PAH); Lipid-based formulations;
Amino acid prodrug of quinidine: An approach to circumvent P-glycoprotein mediated cellular efflux by Mitesh Patel; Nanda K. Mandava; Dhananjay Pal; Ashim K. Mitra (196-204).
In the present study, we investigated the effect of large neutral amino acid modification in overcoming P-gp mediated cellular efflux of quinidine. L-isoleucine ester prodrug of quinidine (Ile-quinidine) was synthesized in our laboratory. [14C]-erythromycin was selected as a model substrate to study interaction of quinidine and Ile-quinidine with P-gp. Transport studies were conducted to study translocation kinetics of quinidine and Ile-quinidine in MDCK-MDR1 cells. In cellular accumulation study, uptake rate of [14C]-erythromycin elevated drastically in presence of cyclosporine A and GF 120918. This result indicates that [14C]-erythromycin is an excellent substrate of P-gp. Similarly, uptake rate of [14C]-erythromycin was enhanced significantly in presence of quinidine (25 and 50 μM). However, [14C]-erythromycin uptake rate remained fairly constant in presence of Ile-quinidine (25 μM). Apparent A-B and B-A permeability of quinidine observed in MDCK-MDR1 cells were 1.6 ± 0.2 × 10−6 and 7.0 ± 0.4 × 10−6 cm/s, a 4.4-fold difference. Moreover, A-B permeability of quinidine increased dramatically in the presence of cyclosporine A and GF 120918. Apparent permeability values of Ile-quinidine observed from A-B and B-A direction were 4.3 ± 0.9 × 10−6 and 5.5 ± 0.4 × 10−6 cm/s, a 1.3-fold difference. Importantly, A-B transport of Ile-quinidine did not change dramatically in the presence of cyclosporine and GF 120918. Based on these results, it was apparent that quinidine displayed higher substrate affinity toward P-gp relative to Ile-quinidine. Chemical or enzymatic hydrolysis of Ile-quinidine resulted in regeneration of low quantities of quinidine during transport studies. Competitive inhibition studies demonstrated that Ile-quinidine was recognized by multiple amino acid transporters such as LAT1, LAT2 and cationic amino acid transporter. In conclusion, chemical modification of quinidine with neutral amino acids results in circumvention of P-gp mediated drug efflux. Hence, amino acid transporter targeted prodrug delivery seems to be a viable strategy for improving drug accumulation in P-gp overexpressing cells.
Keywords: Prodrugs; Ile-quinidine; P-gp circumvention; Uptake; Transport; LAT1 transporter;
The effect of HPMCAS functional groups on drug crystallization from the supersaturated state and dissolution improvement by Keisuke Ueda; Kenjirou Higashi; Keiji Yamamoto; Kunikazu Moribe (205-213).
The inhibitory effect on drug crystallization in aqueous solution was evaluated using various forms of hydroxypropyl methylcellulose acetate succinate (HPMCAS). HPMCAS suppressed crystallization of carbamazepine (CBZ), nifedipine (NIF), mefenamic acid, and dexamethasone. The inhibition of drug crystallization mainly derived from molecular level hydrophobic interactions between the drug and HPMCAS. HPMCAS with a lower succinoyl substituent ratio strongly suppressed drug crystallization. The inhibition of crystallization was affected by pH, with the CBZ crystallization being inhibited at a higher pH due to the hydrophilization of HPMCAS derived from succinoyl ionization. The molecular mobility of CBZ in an HPMCAS solution was evaluated by 1D-1H NMR and relaxation time measurements. CBZ mobility was strongly suppressed in the HPMCAS solutions where strong inhibitory effects on CBZ crystallization were observed. The mobility suppression of CBZ in the HPMCAS solution was derived from intermolecular interactions between CBZ and HPMCAS leading to an inhibition of crystallization. The effect of HPMCAS on the drug dissolution rate was evaluated using an NIF/HPMCAS solid dispersion. The dissolution rate of NIF was increased when HPMCAS with a higher succinoyl substituent ratio was used.
Keywords: HPMCAS; Crystallization inhibition; 1H NMR measurements; NMR relaxation time; Dissolution test;
Albumin-bound nanoparticles of practically water-insoluble antimalarial lead greatly enhance its efficacy by Nehal Ibrahim; Hany Ibrahim; Jerome Dormoi; Sébastien Briolant; Bruno Pradines; Alicia Moreno; Dominique Mazier; Philippe Legrand; Françoise Nepveu (214-224).
We recently showed that the indolone-N-oxides can be promising candidates for the treatment of chloroquine-resistant malaria. However, the in vivo assays have been hampered by the very poor aqueous solubility of these compounds resulting in poor and variable activity. Here, we describe the preparation, characterization and in vivo evaluation of biodegradable albumin-bound indolone-N-oxide nanoparticles. Nanoparticles were prepared by precipitation followed by high-pressure homogenization and characterized by photon correlation spectroscopy, transmission electron microscopy, differential scanning calorimetry and X-ray powder diffraction. The process was optimized to yield nanoparticles of controllable diameter with narrow size distribution suitable for intravenous administration, which guarantees direct drug contact with parasitized erythrocytes. Stable nanoparticles showed greatly enhanced dissolution rate (complete drug release within 30 min compared to 1.5% of pure drug) preserving the rapid antimalarial activity. The formulation achieved complete cure of Plasmodium berghei-infected mice at 25 mg/kg with parasitemia inhibition (99.1%) comparable to that of artesunate and chloroquine and was remarkably more effective in prolonging survival time and inhibiting recrudescence. In ‘humanized’ mice infected with Plasmodium falciparum, the same dose proved to be highly effective: with parasitemia reduced by 97.5% and the mean survival time prolonged. This formulation can help advance the preclinical trials of indolone-N-oxides. Albumin-bound nanoparticles represent a new strategic approach to use this most abundant plasma protein to target malaria-infected erythrocytes.
Keywords: Antimalarial; Indolone-N-oxides; Nanoparticles; Human serum albumin; High pressure homogenization;
Folate-decorated PEG–PLGA nanoparticles with silica shells for capecitabine controlled and targeted delivery by Kun Wei; Xiaomin Peng; Fen Zou (225-233).
Di-block polymer of poly (lactic-co-glycolic acid)–poly (ethylene glycol) (PLGA–PEG) end-capped with capecitabine (CAP) at the hydrophobic domain and folate (FA) at hydrophilic domain were synthesized respectively. The products were extensively studied by nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC) measurement. By using emulsion–solvent evaporation method, the two conjugates, drug CAP and tetramethoxysilane (TMOS) were mixed to form the CAP entrapped nanoparticles (NPs) with the FA moieties exposed on NPs surface, while simultaneously forming a cross-linked silica shell out of hydrophobic PLGA core domain. The testing results showed the CAP-loaded NPs presented suitable physical stability, favorable size around 200 nm, negative zeta potential charge (−28.43 ± 2.55 mV) and high encapsulation efficiency (69%). Both silica shell cross-linked drug-loaded NPs (SSCL NPs) and none silica shell cross-linked NPs (NSSCL NPs) provided an initial burst release and followed by a sustained two-stage release of the CAP. Straight lines approximate the steady-state for the two-stage release, and the K/K′ of the two stages are 1.96304 and 1.78697 respectively suggesting the silica shell influenced the release of first stage significantly.
Keywords: Nanoparticles; Capecitabine; TMOS; PEG–PLGA; Two stage drug release;
Quality by Design approach to spray drying processing of crystalline nanosuspensions by Sumit Kumar; Rajeev Gokhale; Diane J. Burgess (234-242).
Quality by Design (QbD) principles were explored to understand spray drying process for the conversion of liquid nanosuspensions into solid nano-crystalline dry powders using indomethacin as a model drug. The effects of critical process variables: inlet temperature, flow and aspiration rates on critical quality attributes (CQAs): particle size, moisture content, percent yield and crystallinity were investigated employing a full factorial design. A central cubic design was employed to generate the response surface for particle size and percent yield. Multiple linear regression analysis and ANOVA were employed to identify and estimate the effect of critical parameters, establish their relationship with CQAs, create design space and model the spray drying process. Inlet temperature was identified as the only significant factor (p value <0.05) to affect dry powder particle size. Higher inlet temperatures caused drug surface melting and hence aggregation of the dried nano-crystalline powders. Aspiration and flow rates were identified as significant factors affecting yield (p value <0.05). Higher yields were obtained at higher aspiration and lower flow rates. All formulations had less than 3% (w/w) moisture content. Formulations dried at higher inlet temperatures had lower moisture compared to those dried at lower inlet temperatures.
Keywords: Nano-suspension; Spray drying; Re-dispersion; QbD; Nano-crystalline; Spray dried powder;
Preparation and pharmaceutical evaluation of nano-fiber matrix supported drug delivery system using the solvent-based electrospinning method by Mami Hamori; Shiori Yoshimatsu; Yuki Hukuchi; Yuki Shimizu; Keizo Fukushima; Nobuyuki Sugioka; Asako Nishimura; Nobuhito Shibata (243-251).
In this study, utilizing the solvent-based electrospinning (ES) method, which is mainly employed in the textile industry, we prepared nanofiber-based capsules including drugs for controlled-release delivery systems using methacrylic acid copolymer (EUDRAGIT® S100, MAC) as a polymer, and evaluated their in vitro drug dissolution profiles and in vivo pharmacokinetics in rats. As the model drugs, uranine (UN) was used as a water-soluble drug and nifedipine (NP) as a water-insoluble drug. The mean diameters of drug free nano-fiber and nano-fiber including NP or UN were 751.5 ± 67.2, 703.3 ± 71.2 and 2477.8 ± 206.1 nm, respectively. X-ray diffraction for the nano-fibrotic sheet showed that UN and/or NP were packed in nano-fiber in an amorphous form. The in vitro release of UN or NP from the nano-fiber packed capsules (NFPC) and milled-powder of nano-fiber packed capsules (MPPC) showed controlled release of UN or NP as compared to capsules of a physical mixture of MAC and each drug. An in vivo pharmacokinetic study in rats after intraduodenal administration of NFPC or MPPC including UN and/or NP clearly demonstrated that application of nano-fibrotic technique as a drug delivery system offers drastic changes in pharmacokinetic profiles for both water-soluble and water-insoluble drugs. The ES method is a useful technique to prepare a nano-fiber like solid dispersion for polar or nonpolar drugs, and has wide potential pharmaceutical applications.
Keywords: Electrospinning; Nanofiber; Pharmacokinetics; Controlled-release; Drug delivery system;