European Journal of Pharmaceutics and Biopharmaceutics (v.75, #3)
Repeated siRNA application is a precondition for successful mRNA γENaC knockdown in the murine airways
by Guelnihal Yueksekdag; Marei Drechsel; Michaela Rößner; Christa Schmidt; Michael Kormann; Marta C. Illenyi; Carsten Rudolph; Joseph Rosenecker (pp. 305-310).
The volume of the airway surface liquid is regulated by Na+ absorption and Cl− secretion by the respiratory epithelium. In cystic fibrosis, Na+ hyperabsorption caused by the absence of functional CFTR protein leads to an altered airway surface liquid composition and finally to a deteriorated mucociliary clearance. It has been suggested that down regulation or inhibition of the amiloride-sensitive epithelial Na+ channel (ENaC) could restore the disrupted airway hydration. Therefore, targeting ENaC by RNA interference could be of therapeutic relevance. In this context, we investigated whether RNAi could lead to a reduction in γENaC expression in epithelia in vitro and in vivo in mice. Transfection of cells with specific siRNA sequences for γENaC subunit reduced expression to ∼10% relative to control. For in vivo experiments, siRNA sequences specific for the γENaC subunit were administered to the murine nasal cavity and, 72h later the animals were killed. In the first approach, only a single application of naked siRNA was given. In the second approach, repeated siRNA applications were performed. The single application of siRNA sequences had no effect on mRNA content of the targeted γENaC subunit, whereas repeated siRNA application resulted in a significant reduction in γENaC mRNA in the respiratory tissue. We conclude that repeated siRNA application is necessary for γENaC knockdown in the murine airways.
Keywords: ENaC; Cystic fibrosis; Airways; siRNA; Gene silencing; In vivo
Enhanced gene expression in epithelial cells transfected with amino acid-substituted gemini nanoparticles
by Peng Yang; Jagbir Singh; Shawn Wettig; Marianna Foldvari; Ronald E. Verrall; Ildiko Badea (pp. 311-320).
Gemini surfactants are versatile gene delivery agents because of their ability to bind and compact DNA and their low cellular toxicity. Through modification of the alkyl tail length and the chemical nature of the spacer, new compounds can be generated with the potential to improve the efficiency of gene delivery. Amino acid (glycine and lysine) and dipeptide (glycyl-lysine and lysyl-lysine) substituted spacers of gemini surfactants were synthesized, and their efficiency of gene delivery was assessed in epithelial cells for topical cutaneous and mucosal applications.Three different epithelial cell lines, COS-7, PAM212 and Sf 1Ep cells, were transfected with plasmid DNA encoding for interferon gamma and green fluorescent protein complexed with the amino acid-substituted gemini compounds in the presence of 1,2 dioleyl- sn-glycero-phosphatidyl-ethanolamine as a helper lipid. Gene expression was quantified by ELISA. Size, zeta potential and circular dichroism measurements were used to characterize the plasmid–gemini (PG) and plasmid–gemini surfactant–helper lipid (PGL) complexes.Gene expression was found to increase up to 72h and then declined by the 7th day. In general, the glycine-substituted surfactant showed consistently high gene expression in all three cell lines. Results of physicochemical and spectroscopic studies of the complexes indicate that substitution of the gemini spacer does not interfere with compaction of the DNA.The superior performance of these spacer-substituted gemini surfactants might be attributed to their better biocompatibility compared to the surfactants possessing unsubstituted spacers.
Keywords: Gene therapy; In vitro; transfection; Non-viral; Epithelial cells; Nanoparticles; Delivery efficiency
Palmitoyl ascorbate-modified liposomes as nanoparticle platform for ascorbate-mediated cytotoxicity and paclitaxel co-delivery
by Rupa R. Sawant; Onkar S. Vaze; Karen Rockwell; Vladimir P. Torchilin (pp. 321-326).
Schematic representation of palmitoyl ascorbate liposomes and detection of reactive oxygen species generation in vitro with CM-H2DCFDA dye by fluorescence microscopy in cancer cells. Left figure shows the bright field and right figure shows the fluorescent field of RAG cells treated with plain-liposomes (A), and PA-liposomes (B).Ascorbate has multiple biological roles and chemical interactions, some of which differ between normal and cancerous tissues. Biological effects of ascorbate depend on concentration, route of exposure, and duration of exposure. High-dose ascorbate acts as a pro-oxidant in tissue fluids and delivers peroxide to tissues and fluids, which is then detoxified by erythrocytes and plasma catalase in normally perfused areas. We have previously shown that nanoparticles incorporating palmitoyl ascorbate (PA) targeted and killed cancer cells in vitro. Here, our studies provide additional indications of the importance of extracellular reactive oxygen species (ROS) in the anti-cancer-toxicity by PA-liposomes. Cell death in vitro can be blocked by catalase, superoxide dismutase, and the thiol reductant TCEP. Intracellullar iron may also play a role. Iron chelation by desferrioxamine inhibited cell death but EDTA did not. Further, the fluorescent marker of ROS production in cells indicated that the PA-liposomes caused an increase in ROS. Fluorescent microscopy of tumor sections taken at 3h after injection of rhodamine-labeled liposomes demonstrated an increased accumulation of PA-liposomes compared to plain liposomes. However, the overall biodistribution of111In-labeled PA-liposomes was similar to plain liposomes. PA-liposomes provided substantial anti-tumor activity in vivo and enhanced the anti-cancer activity of liposomally encapsulated paclitaxel. Thus, nanoparticles incorporating PA provide a platform for enhancement of the anti-tumor activity of ascorbate.
Keywords: Palmitoyl ascorbate; Liposomes; Paclitaxel; Nanoparticles; Reactive oxygen species; Cancer
Distearoylphosphatidylethanolamine-based liposomes for ultrasound-mediated drug delivery
by Tove J. Evjen; Esben A. Nilssen; Sibylla Rögnvaldsson; Martin Brandl; Sigrid L. Fossheim (pp. 327-333).
Development of liposomes for ultrasound-mediated drug delivery.The ability of ultrasound (US) to permeabilize phospholipid membranes has opened the potential of using US as a means to enhance delivery of anti-cancer drugs to tumour cells via liposomes. In this study, novel US sensitive or sonosensitive doxorubicin-containing liposomes based on 1,2 distearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE) as the main lipid component are reported. A variety of lipid bilayer compositions was studied with respect to in vitro US triggered release of drug as well as serum stability in terms of drug retention, using experimental design. The multivariate data analysis indicated a strong correlation between DSPE content and sonosensitivity, both alone and in interplay with cholesterol. The most optimal formulation showed approximately 70% release of doxorubicin after 6min of US exposure. This represented a 7-fold increase in release extent when compared to standard pegylated liposomal doxorubicin. The significant enhancement in sonosensitivity of the liposomes shows the potential of engineering liposomal lipid composition for US-mediated drug delivery.
Keywords: Liposome; Lipids; Ultrasound; Drug delivery; Cancer; DoxorubicinAbbreviations; US; ultrasound; Chol; cholesterol; DSPE; 1,2 distearoyl-sn-glycero-3-phosphatidylethanolamine; DSPE-PEG; 1,2 distearoyl-sn-glycero-3-phosphatidylethanolamine-N-(methoxy(polyethylene glycol)-2000); DSPC; 1,2 distearoyl-sn-glycero-3-phosphatidylcholine; HSPC; hydrogenated (soy) L-α-phosphatidylcholine; DXR; doxorubicin; E; phosphatidylethanolamine; L; α; lamellar liquid-crystalline phase; H; II; inverted hexagonal phase
Enhanced cytotoxicity and activation of ROS-dependent c-Jun NH2-terminal kinase and caspase-3 by low doses of tetrandrine-loaded nanoparticles in Lovo cells – A possible Trojan strategy against cancer
by Xiaolin Li; Donghui Zhen; Xiaowei Lu; Hua’e Xu; Yun Shao; Qiping Xue; Yong Hu; Baorui Liu; Weihao Sun (pp. 334-340).
The Trojan strategy of nanoparticle-based Tet delivery can effectively lead to higher cell death compared to equivalent dose of free Tet. The differential cytotoxicity between Tet and Tet-loaded nanoparticles may probably be mediated by the discrepancy of intracellular ROS levels and sequential activation of ROS-dependent JNK and caspase-3.Tetrandrine (Tet), a bis-benzylisoquinoline alkaloid, has recently been reported as a novel anti-cancer agent in vitro and in vivo by inducing apoptosis with the formation of reactive oxygen species (ROS) and the activation of ROS-dependent c-Jun NH2-terminal kinase (JNK) and caspase-3. However, application of Tet is limited for its insolubility. Accumulated evidences raise the possibility of developing nanoscale delivery systems of Trojan strategy with improved solubility, stability and cytotoxicity of lipophilic Tet. Here, we reported first a simple way to produce Tet-loaded nanoparticles based on amphiphilic block copolymer. The controlled release pattern of Tet-loaded nanoparticles (Tet-np) was characterized by in vitro release experiments. Cytotoxicity tests proved anti-tumor effect of Tet-np against Lovo cells. Moreover, doses of Tet-np during lower concentrations (1–8μg/ml) led to more cell inhibition than equivalent doses of free Tet did (1–8μg/ml). It was further presented that the higher uptake efficiency, more reactive oxygen species (ROS) generation, and the stronger activation of ROS-dependent c-Jun NH2-terminal kinase (JNK) and caspase-3 were induced by the equivalent dose of Tet delivered by nanoparticles. Although the present results suggested that Tet-np could be a potential useful chemotherapeutic tool, intensive researches are still warranted.
Keywords: Tetrandrine; Nanoparticle; Anti-tumor; Reactive oxygen species (ROS); c-Jun NH; 2; -terminal kinase; Caspase-3
Enhanced antitumor efficacy by Paclitaxel-loaded Pluronic P123/F127 mixed micelles against non-small cell lung cancer based on passive tumor targeting and modulation of drug resistance
by Zhang Wei; Shi Yuan; Yanzuo Chen; Shuangyin Yu; Junguo Hao; Jieqi Luo; Xianyi Sha; Xiaoling Fang (pp. 341-353).
The therapeutic improvement of PF-PTX in vivo against A-549 MDR tumor was obtained based on passive tumor targeting and modulation of drug resistance.The aim of this work was to demonstrate the advantage of using paclitaxel (PTX)-loaded Pluronic P123/F127 mixed micelles (PF-PTX) against non-small cell lung cancer (NSCLC) compared to Taxol. Modulation of multidrug resistance (MDR) by Pluronic mixed micelles was evaluated in lung resistance protein (LRP)-overexpressing human lung adenocarcinoma A-549 cell line. Influence of PF-PTX on in vitro cytotoxicity was determined by MTT assay, while cellular apoptosis was detected by cell nuclei staining and Annexin V-FITC apoptosis detection kit. Cell cycle arrest was also confirmed by flow cytometry. Additionally, in vivo fate and antitumor efficacy of PF-PTX were extensively evaluated in comparison with Taxol. It was demonstrated that PF-PTX had superior anti-proliferation activity against A-549 cells compared with Taxol as measured by IC50. The enhanced anti-cancer efficacy of PF-PTX was associated with PTX-induced apoptosis and cell arrest in the G2/M phase. Intracellular ATP depletion and decreased mitochondrial potential caused by Pluronic copolymers were found to be related to modulation of MDR. PF-PTX also exhibited significant advantages in pharmacokinetics and A-549 xenograft tumor model versus Taxol. The PF-PTX formulation achieved 3.0-fold longer mean residence time in circulation, 2.2-fold larger area under the plasma concentration–time curve than Taxol. At 28days, tumor volume in PF-PTX group was only 31.8% that of the Taxol. Therefore, PF-PTX significantly enhanced the anti-cancer activity of PTX and might be considered a promising drug delivery system to overcome MDR in lung cancer.
Keywords: Polymeric micelles; Paclitaxel; Pluronic; A-549; Multidrug resistance
Combined use of ordered mesoporous silica and precipitation inhibitors for improved oral absorption of the poorly soluble weak base itraconazole
by Michiel Van Speybroeck; Raf Mols; Randy Mellaerts; Thao Do Thi; Johan A. Martens; Jan Van Humbeeck; Pieter Annaert; Guy Van den Mooter; Patrick Augustijns (pp. 354-365).
The release of poorly soluble drugs from mesoporous silicates is often associated with the generation of supersaturation, which implies the risk of drug precipitation and reduced availability for absorption. The aim of this study was to enhance the in vivo performance of an ordered mesoporous silicate (SBA-15) by combining it with the precipitation inhibitors hydroxypropylmethylcellulose (HPMC) and hydroxypropylmethylcellulose acetate succinate (HPMCAS). The poorly soluble weak base itraconazole was used as a model compound. Formulations were prepared by physically blending itraconazole-loaded SBA-15 with the precipitation inhibitors. In vitro release experiments implementing a transfer from simulated gastric fluid to simulated intestinal fluid were used to evaluate the pharmaceutical performance. Subsequently, the formulations were evaluated in vivo in rats. When high enough amounts of HPMC were co-administered with itraconazole-loaded SBA-15 (itraconazole:SBA-15:HPMC 1:4:6), the extent of absorption was increased by more than 60% as compared to SBA-15 without precipitation inhibitors (AUC 14937±1617 vs. 8987±2726nM.h). HPMCAS was found ineffective in enhancing the in vivo performance of SBA-15 due to its insolubility in the stomach. The results of this study demonstrate that the pharmaceutical performance of SBA-15 is enhanced through addition of an appropriate precipitation inhibitor.The release of poorly soluble drugs from mesoporous silicates is often associated with the generation of supersaturation, which implies the risk of drug precipitation and reduced availability for absorption. The aim of this study was to enhance the in vivo performance of an ordered mesoporous silicate (SBA-15) by combining it with the precipitation inhibitors hydroxypropylmethylcellulose (HPMC) and hydroxypropylmethylcellulose acetate succinate (HPMCAS). The poorly soluble weak base itraconazole was used as a model compound. Formulations were prepared by physically blending itraconazole-loaded SBA-15 with the precipitation inhibitors. In vitro release experiments implementing a transfer from simulated gastric fluid to simulated intestinal fluid were used to evaluate the pharmaceutical performance. Subsequently, the formulations were evaluated in vivo in rats. When high enough amounts of HPMC were co-administered with itraconazole-loaded SBA-15 (itraconazole:SBA-15:HPMC 1:4:6), the extent of absorption was increased by more than 60% when compared to SBA-15 without precipitation inhibitors (AUC 14,937±1617 versus 8987±2726nMh). HPMCAS was found ineffective in enhancing the in vivo performance of SBA-15 due to its insolubility in the stomach. The results of this study demonstrate that the pharmaceutical performance of SBA-15 is enhanced through addition of an appropriate precipitation inhibitor.
Keywords: Mesoporous silica; SBA-15; Itraconazole; Supersaturation; Precipitation inhibitors; Bioavailability
Carboxyl group-terminated polyamidoamine dendrimers bearing glucosides inhibit intestinal hexose transporter-mediatedd-glucose uptake
by Shinji Sakuma; Yumi Teraoka; Tomokazu Sagawa; Yoshie Masaoka; Makoto Kataoka; Shinji Yamashita; Yoshiyuki Shirasaka; Ikumi Tamai; Yusuke Ikumi; Toshiyuki Kida; Mitsuru Akashi (pp. 366-374).
Carboxyl group-terminated polyamidoamine dendrimers bearing arbutin, which is a substrate of Na+/glucose cotransporter located on the mucosal side of the intestinal epithelial cell as an influx active transporter of glucose, (PAMAM–ARB) significantly suppressed glucose-induced hyperglycemic effects in rats.We are investigating non-absorbable polymeric conjugates bearing glucosides via a ω-amino triethylene glycol linker as oral anti-diabetic drugs that suppress an increase in the blood glucose level after meals through inhibition of Na+/glucose cotransporter (SGLT1). When the linker was bound to phloridzin, which is a SGLT1 inhibitor, to yield a precursor of the conjugate, the in vitro inhibitory effect on SGLT1-mediatedd-glucose uptake was reduced to about one-tenth that of phloridzin. The inhibitory effect was recovered completely when the precursor was immobilized on the surface of poly(amidoamine) (PAMAM) dendrimers (generation: 3.0) by coupling with one-eighth or less of the terminal carboxyl groups. We considered that the phloridzin-derived glucose moiety on the dendrimer surface was prerequisite for SGLT1 inhibition but that the aglycon part was not always required for the inhibition. Commercially used arbutin, a SGLT1 substrate, was substituted for phloridzin whose aglycon is composed of toxic phloretin. The in vitro inhibitory effect of arbutin was about one-thirtieth that of intact phloridzin; however, the inhibitory effect of the PAMAM dendrimer–arbutin conjugates was as strong as that of the PAMAM dendrimer–phloridzin conjugates. Rat experiments further showed that the PAMAM dendrimer–arbutin conjugates significantly suppressedd-glucose-induced hyperglycemic effects. The dendritic conjugate bearing arbutin appears to be a good candidate as an oral anti-diabetic drug.
Keywords: Dendrimer; Glucoside; Hexose transporter; Conjugation; Oral anti-diabetic drug
Drug release from and sterilization of in situ cubic phase forming monoglyceride drug delivery systems
by Abid Riaz Ahmed; Andrei Dashevsky; Roland Bodmeier (pp. 375-380).
Since a monoglyceride-based cubic phase is too viscous to be injected parenterally, mixtures of monoglyceride, water and water-miscible cosolvents were investigated as low viscosity injectable in situ cubic phase-forming formulations. Upon contact with the release medium, a highly viscous cubic phase formed rapidly and served as an extended release matrix for the oligonucleotide drug. Extended drug release was obtained with all formulations. The drug release followed the square root of time relationship indicating a diffusion-controlled release mechanism. The release depended on the type of cosolvent and followed the order of ethanol>PEG 300>2-pyrrolidone>DMSO. Higher water or monoglycerides contents decreased the drug release because of an increased viscosity and increased swollen matrix thickness. The bioburden of different commercially available monoglycerides and of the prepared in situ cubic phase-forming formulations met USP XXIII requirements. Monoglycerides can be successfully sterilized by gamma irradiation or by autoclaving and the in situ cubic phase-forming formulations by autoclaving and aseptic filtration. The monoglycerides and in situ cubic phase-forming formulations retained their phase behaviour and release properties after sterilization.
Keywords: Controlled drug release; In situ; cubic phase; Monoglyceride; Oligonucleotide; Sterilization
Freeze-dried chitosan/pectin nasal inserts for antipsychotic drug delivery
by Barbara Luppi; Federica Bigucci; Angela Abruzzo; Giuseppe Corace; Teresa Cerchiara; Vittorio Zecchi (pp. 381-387).
Chitosan/pectin based nasal inserts have been prepared to improve bioavailability of antipsychotic drugs for the treatment of psychotic symptoms. Morphological characteristics, water uptake, mucoadhesion, release and permeation studies have been performed.The objective of this investigation was the development of chitosan/pectin based nasal inserts to improve bioavailability of antipsychotic drugs in the treatment of psychotic symptoms. In fact, the nasal route of administration ensures systemic availability avoiding the first-pass metabolism and obtaining more efficacious treatments. Chitosan/pectin polyelectrolyte complexes were prepared at pH 5.0 with different polycation/polyanion molar ratios and lyophilized in small inserts in the presence of chlorpromazine hydrochloride. The results show that higher amount of pectin in the complexes, with respect to higher amount of chitosan, produced a more evident porous structure of the nasal inserts, improving water uptake ability and mucoadhesion capacity. Finally, the presence of increasing amounts of pectin allowed the interaction with chlorpromazine hydrochloride inducing the formation of less hydratable inserts thus limiting drug release and permeation. This investigation verifies the formation of polyelectrolyte complexes between chitosan and pectin at pH values in the vicinity of the p Ka interval of the two polymers and confirms the potential of these complexes, capable of achieving antipsychotic drug delivery in the nasal cavity.
Keywords: Chitosan/pectin polyelectrolyte complexes; Nasal delivery; Mucoadhesive inserts; Chlorpromazine hydrochloride
Gel–sol–gel thermo-gelation behavior study of chitosan–inorganic phosphate solutions
by XingYi Li; XiangYe Kong; XiuHong Wang; Shuai Shi; Gang Guo; Feng Luo; Xia Zhao; YuQuan Wei; ZhiYong Qian (pp. 388-392).
In present study, a novel thermo-sensitive hydrogels suitable for injectable formulations based on chitosan and inorganic phosphate was demonstrated. The physicochemical and rheological changes of chitosan/dibasic sodium phosphate solutions were investigated in detail.In present study, the feasibility of developing a novel thermo-sensitive hydrogel suitable for injectable formulations based on chitosan and inorganic phosphate was demonstrated. The physicochemical and rheological changes of chitosan/dibasic sodium phosphate solutions as in function with temperature were investigated in order to gain a better understanding of gelation process. According to the result of rheological study, there are two phase transition points as in function with temperature, corresponding to 30°C and 43°C. The system is gel state at ∼4°C. With the temperature increased to 30°C, the gel–sol transition as well as the decrease in turbidity was observed. The sol–gel transition as well as the increase in turbidity was observed again as the temperature was above 43°C. And the gel obtained at ∼4°C is reversible, but the gel obtained at ∼43°C is irreversible.
Keywords: Chitosan; Thermo-sensitive; Rheology; Physicochemical characterization
Characterisation of solution-based pressurised metered-dose inhaler aerosols with an optical particle counter
by M. Kuhli; M. Weiss; H. Steckel (pp. 393-398).
The White Light Aerosol Spectrometer (welas®) is an alternative method to multistage cascade impaction in the analysis of particle-size distribution (PSD) that allows measurements in high concentrations by single particle measurement. Correspondence of the PSD measured by the welas® system in combination with a new aerosol sampling system has been discussed before for aqueous aerosols from nebulisers [M. Kuhli, M. Weiss, H. Steckel, A sampling and dilution system for droplet aerosols from medical nebulisers developed for use with an optical particle counter, Journal of Aerosol Science 40 (2009) 523-533]. For aerosols from solution-based pressurised metered-dose inhalers (pMDI), both the apparent density and the dynamic shape factor of the dry solid particles come into account for correlation of aerodynamic to scattered light equivalent diameter. The aim of this study was to enable welas® measurements for pMDI aerosols. Equal particle drying properties in cascade impaction (Next Generation Impactor, NGI) and the aerosol sampling system for the welas® should be assured. Therefore, an additional, optionally preheated, extension device was included to modify the aerosol sampling system. The PSD measured with the aerosol sampling system that allowed most complete particle drying was compared to the PSD measured by NGI. The introduction of an empiric calibration allows correlation of NGI and welas® measurements for the investigated solution-based pMDIs.
Keywords: Abbreviations; DF; dilution factor; HFA; hydrofluoroalkane; IP; induction port; MFC; mass flow controller; NGI; Next Generation Pharmaceutical Impactor; Ph. Eur.; European pharmacopoeia; pMDI; pressurised metered-dose inhaler; PSD; particle-size distribution; SEM; scanning electron microscopyAerosol particle sizing; Cascade impaction; Pressurised metered-dose inhaler; Light-scattering aerosol spectrometer; Aerosol sampling system
Adhesion testing of transdermal matrix patches with a probe tack test – In vitro and in vivo evaluation
by Eva Gutschke; Stefan Bracht; Stefan Nagel; Werner Weitschies (pp. 399-404).
It was the aim of the study to evaluate the suitability of the probe tack test as a method of predicting the long-term adhesion properties of transdermal patches to human skin. Twelve different types of polyacrylate pressure sensitive adhesives have been characterized using the probe tack test. For the analysis of the obtained data a novel procedure was developed that is based on two parameters: the deformation compliance κ and the critical return speedv c. In addition to the in vitro characterization, the in vivo adhesive properties were investigated in a double-blinded and randomized wear study by eight volunteers for a period of 7days of wear. The adherent area and the size of the dark ring were defined in a percentage of the patch area by analysing digital photographs. The in vitro data correlate mostly with the in vivo performance of the tested adhesives after 7days. Accordingly, the probe tack test could be a helpful tool during the development of transdermal patches.
Keywords: Adhesion; Pressure sensitive adhesive; PSA; Transdermal patch; Probe tack test
Prediction of blood–brain barrier penetration of poorly soluble drug candidates using surface activity profiling
by Anna Christine Petereit; Kelly Swinney; Jurgen Mensch; Claire Mackie; Sigrid Stokbroekx; Marcus Brewster; Jennifer B. Dressman (pp. 405-410).
The aim of this study was to determine whether transepithelial transport across the blood–brain barrier (BBB) [expressed as the logarithm of blood/brain partitioning coefficient (logbb)] could be correlated to surface tension properties for a series of new chemical entities (NCEs) having extremely low solubility in aqueous media.Surface tension data were generated by the “Du Nouy maximum pull force method” using an automated, small volume Kibron Delta 8 Multi-channel tensiometer. Using the surface pressure/concentration profiles, parameters such as the maximum surface pressure, cross-sectional area and the air–water partitioning coefficient were calculated for the individual compounds and correlated with their in vivo logbb values. A good linear correlation ( R2=0.8669) between logbb and cross-sectional area was observed, suggesting a morphological analogy between the molecular orientation at the air–water interface and the anisotropic cellular bilayer of the blood–brain barrier.
Keywords: Surface activity profiling; Drug discovery; Maximum surface pressure; Cross-sectional area; Blood–brain barrier; Gibbs adsorption isotherms
A novel diffusion cell model for the in vitro assessment of transcutaneous breast cancer therapeutics: Effect of permeants on MCF-7 cells cultured within the receptor compartment
by Zoë Davison; Robert I. Nicholson; Stephen P. Denyer; Charles M. Heard (pp. 411-417).
A novel model is described for investigating the potential efficacy of topically delivered anti-breast cancer agents. Using all-glass Franz diffusion cells, the permeation of 4-hydroxytamoxifen, two EGFR inhibitors (PD98059 and LY294002) and eicosapentaenoic acid (EPA) were determined from a fish oil vehicle across Cyclopore track etched membrane (CTEM) alone, full-thickness porcine ear skin alone and CTEM plus full-thickness porcine ear skin. Finally, the effect of the simultaneous permeation of these compounds was determined on the breast cancer cell line, MCF-7, cultured directly into the diffusion cell receptor compartments. The CTEM was found to be not rate limiting, and all compounds permeated the skin, with a large excess of EPA. The applied combined dose reduced the growth of MCF-7 cells by 66% after 7days. The following conclusions were obtained: (1) MCF-7 breast cancer cells can be successfully cultured within glass Franz diffusion cells. (2) A composite diffusion cell/cell culture model can indicate the potential efficacy of topically delivered anti-breast cancer therapeutic agents. (3) The levels of LY294002, PD98059, 4-hydroxytamoxifen and EPA delivered across full-thickness skin have a major inhibitory effect on the growth of MCF-7 breast cancer cells.
Keywords: Breast cancer; Topical drug delivery; 4-Hydroxytamoxifen; EGFR inhibitors; PD98059; LY294002; Eicosapentaenoic acid; Cyclopore track etched membrane; Franz diffusion cell; Skin; Composite model
Construction of a quality index for granules produced by fluidized bed technology and application of the correspondence analysis as a discriminant procedure
by Teresa Albuquerque; Vitor H. Dias; Norbert Poellinger; João F. Pinto (pp. 418-424).
The production of granules by wet granulation in a fluidized bed was assessed after the construction of a quality index based on a file of attributes (relevant factors). These attributes are combined by a methodology relying on Correspondence Analysis, as a discriminant procedure, using two extreme simulated active vectors representing, respectively, the best and the worst cases for the granules quality output (“bad” and “good” pole). From those, a single continuous synthetic variable – the quality index – can be produced referring to a more significant set of samples. As an application of the methodology, the work compares the quality of granules produced at a laboratory scale and a pilot scale. The factors contribution to the bad or good pole allowed the identification of the most relevant factors that affect the quality of the granules. The factors studied, according to a center of gravity design, included formulation (solubility of a drug, different grades of polyvinylpyrrolidone, the polarity of the granulation solution) and processing factors (the rate of administration of the granulation solution, the atomizing air pressure and the fluidizing air rate). Granules were evaluated for production yield, drug content, size, densities (true, bulk and tapped), friability, flowability and compressibility. The study has emphasized the differences between the laboratory and pilot scales and the relative importance of each factor for the quality of the granules produced.
Keywords: Correspondence Analysis; Fluidized bed; Granulation; Quality index; Relevant factors
A statistical approach to evaluate the potential use of compression parameters for classification of pharmaceutical powder materials
by Ingvild Klevan; Josefina Nordström; Ingunn Tho; Göran Alderborn (pp. 425-435).
The current work aims to investigate whether a multivariate statistical approach could reveal latent structures in compression data and group powders with respect to their compression behavior in a way that is consistent with an earlier proposed classification system. Seventeen pharmaceutically relevant materials, exhibiting a wide range of mechanical properties, were used as supplied, compressed, and parameters from three commonly used powder compression models (Kawakita parameters a and b−1, the rearrangement index ab, the Shapiro f parameter and HeckelP y) were retrieved. Multivariate analysis of the compression parameters was done with a Principal Component Analysis (PCA). It was found that the latent structures could be divided into three main parts; the most variation was found in the direction associated with particle rearrangement, second largest variation was found in the direction described by the particle fragmentation propensity, and the least variation was found in the direction associated with the plasticity of the particles. This work demonstrates that a combination of the selected compression parameters could be utilized to find relevant differences in compression behavior for a wide range of materials, and that this information can be presented in an efficient way by applying multivariate data analysis techniques.
Keywords: Classification system; Compression; Fragmentation; Particle rearrangement; Powders; Principal Component Analysis (PCA)
Novel compaction techniques with pellet-containing granules
by Xin Pan; Meiwan Chen; Ke Han; Xinsheng Peng; Xinguo Wen; Bao Chen; Jin Wang; Ge Li; Chuanbin Wu (pp. 436-442).
A novel technique of granulating pellets was introduced in pellets compaction, and a segregation-free combination of pellet-containing granules and cushioning granules were achieved. The uniformity of tablets prepared by this new method was improved comparing to traditional method.The purpose of this investigation was to introduce a new concept of admixing coated pellets with excipients to obtain a segregation-free combination of pellet-containing granules and cushioning granules during mixing and compression.Acrylic polymeric-coated pellets were granulated by centrifugal granulation method with excipients; then, the pellet-containing granules were compacted into tablets with the cushioning granules, which were prepared in mixer or fluidized bed-granulator. Tablets were also made in a traditional method by directly compressing the mixtures of coated pellets and cushioning granules for control. Drug-release profiles, weights and drug content of tables were tested to compare this new method with the traditional method.The granulation process changed the surface morphology of coated pellets from smooth to rough and increased the angle of repose of pellets to close to that of the cushioning granules. Weight and drug content RSD values of tablets prepared by pellet-containing granules were much lower than those of tablets prepared by coated pellets. The similarity factor f2 values for drug-release profiles of tablets prepared from pellet-containing granules and the original coated pellets were above 50 when microcrystalline cellulose (MCC), Polyplasdone® XL (PVPP), and lactose were used as granulating excipients.The granulation process could roughen the surface of coated pellets and increase the angle of repose and uniformity of the mixture with cushioning granules. Compared with the tablets directly compressed from coated pellets, the tablets prepared by pellet-containing granules showed improved uniformity in both weight and drug content. The granulation and compression processes did not significantly influence the drug-release behavior of coated pellets, and the enteric dissolution was retained.
Keywords: Coated pellets; Pellet-containing granules; Enteric polymers; Acrylic polymers; Uniformity tablets; Centrifugal granulation
Polymorphism of Irganox 1076®: Discovery of new forms and direct characterization of the polymorphs on a medical device by Raman microspectroscopy
by Johanna Saunier; Vincent Mazel; Céline Paris; Najet Yagoubi (pp. 443-450).
SEM image of the surface of a polyurethane catheter with several clusters of needles. As shown by the Raman spectra, these needles correspond to the antioxidant (Irganox 1076) added to the polymer. The polymorph is not the commercially available form but corresponds to one of the three other forms we put into evidence.Irganox 1076® (octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate) is a common phenolic antioxidant used in many polymer-based medical devices. As with many organic compounds, several polymorphs exist. However, in literature, only two forms of Irganox 1076® have been mentioned. In this study, we were able to produce, by crystallization in different solvents, three distinct polymorphs, which were characterized by DSC, FTIR and PXRD. Moreover, the three polymorphs have long-time stability at ambient pressure and temperature, meaning that they can potentially be present in or on polymeric devices. During DSC measurements, a fourth polymorph, which was only stable at low temperature, was evidenced.Thanks to Raman microspectroscopy, Irganox 1076® was identified directly on commercial polyurethane catheters which exhibited a blooming phenomenon. This study proves that the polymorph identified on the surface is different from the commercially available Irganox 1076®. These results emphasize the importance of the screening of polymorphs before any study of the biocompatibility of antioxidants used in medical devices.
Keywords: Polymorphism; Blooming; Raman; Antioxidant; Medical device; FTIR
In vivo evaluation of albendazole microspheres for the treatment of Toxocara canis larva migrans
by María G. Barrera; Darío Leonardi; Raul E. Bolmaro; Claudia G. Echenique; Alejandro C. Olivieri; Claudio J. Salomon; María C. Lamas (pp. 451-454).
Albendazole is a benzimidazole derivative with proven efficacy against many parasites such as intestinal helminths. Toxocariasis is one of the important parasitic diseases in humans and animals caused by Toxocara canis. It is well known that T. canis larvae migrate in paratenic hosts, including humans where it may cause visceral larva migrans. Thus, the present research was carried out using in vivo experiments with the aim of finding whether novel albendazole microparticles would be active against migrating larvae of the parasite. Albendazole–chitosan microparticles were prepared by ionotropic gelation with sodium lauryl sulphate or by a liquid–liquid phase separation with sodium hydroxide. Mice were infected with T. canis and then treated with both albendazole–chitosan microparticles. After treatment (28days post-infection), it was examined the anthelmintic effect in mice after oral administration of microparticulate preparations. The number of larvae recovered from mice treated with albendazole formulations were compared with placebo. The results showed that albendazole microparticles were easily prepared in high yield using both aqueous solutions of sodium lauryl sulphate or sodium hydroxide. In vivo evaluation of larva migration showed that albendazole microparticles exhibited a greater anthelmintic effect in the brain (0 larva/mouse). In addition, it was also found that liver and lung showed a significant decrease in the number of larvae. Therefore, these data suggest that albendazole–chitosan microparticles are effective formulations for the treatment of toxocariasis infection by reducing the number of larvae in liver and lung. Particularly, these polymeric preparations were able to totally prevent migration of larvae to the mice brain.
Keywords: Chitosan microparticles; Albendazole; Toxocariasis; Nematocide activity; Migrating larvae