International Journal of Pharmaceutics (v.476, #1-2)
EDITORIAL BOARD (iii).
The improved blood–brain barrier permeability of endomorphin-1 using the cell-penetrating peptide synB3 with three different linkages by Hui Liu; Wei Zhang; Linnan Ma; Linlan Fan; Feiyun Gao; Jingman Ni; Rui Wang (1-8).
Display OmittedEndomorphins, although they have high analgesic activity and few undesirable side effects, are not in clinical use because of the blood–brain barrier (BBB). One promising solution is to use cell-penetrating peptides (CPPs). CPPs have the ability to translocate cell membranes and have been successfully applied for delivery of therapeutic molecules across the BBB. However, little is known about the transport efficiency of different conjugation strategies between cargo and CPPs. In this study, endomorphin-1 (EM-1) was conjugated with SynB3, an efficient CPP-carrier, via amide, maleimide and disulfide linkages. The delivery efficiency of three linkers was compared in terms of pharmacodynamics and in vitro metabolic stability. Near-infrared fluorescent and fluorescent microscopy experiments were applied to detect the brain uptake and distribution of CPP delivery qualitatively and quantitatively. After the most successful linkage was screened out, the further mechanisms were discussed. We concluded that compared with the other two linkages, the disulfide bond was the most efficient linkage to deliver EM-1 across the BBB and confirmed that it could be reduced at physiological conditions in the brain and release its active form. These findings indicate that for those who need to release a free drug in the brain and maintain activity, a disulfide bond might be the most efficient linkage across the BBB.
Keywords: Endomorphin-1; Cell penetrating peptides; SynB3; Covalent linkage; Brain delivery;
Vitamin E-based micelles enhance the anticancer activity of doxorubicin by Fabienne Danhier; Trésor Touan Bi Kouhé; Nicolas Duhem; Bernard Ucakar; Aurélie Staub; Nihed Draoui; Olivier Feron; Véronique Préat (9-15).
Display OmittedThe purpose of this study was to develop vitamin E-based micelles loaded with Doxorubicin (DOX) (DOX–TOS–TPGS), taking advantages of the anti-cancer activity of vitamin E derivatives: Tocopherol succinate (TOS) and d-α-tocopherol polyethylene2000 succinate (TPGS). Therefore, we developed micelles consisting in a mixture of TOS (as solubilizer) and TPGS2000 (as stabilizer) (1:1). DOX–TOS–TPGS micelles exhibited a size of 78 nm and a ζ potential of −7 mV. High drug loading (40% w/w) was achieved. The critical micellar concentration was determined at 14 μg/ml. In vitro, after 24 h, DOX-TOS- TPGS micelles exhibited higher cytotoxicity than free-DOX (IC50 on MCF-7 cells, at 24 h, 58 vs 5 μg/ml). In vivo anti-tumor efficacy, performed on two tumor models (CT26 and MCF-7), demonstrated a 100% long-term survival of mice when treated with DOX–TOS–TPGS compared to DOX-free. Interestingly, the survival time of mice treated with unloaded TOS–TPGS micelles was similar to DOX-free, indicating an anti-cancer activity of vitamin E derivatives. Based on these results, it can be concluded that the formulations developed in this work may be considered as an effective DOX delivery system for cancer chemotherapy.
Keywords: Micelles; Doxorubicin; Nanomedicines; Vitamin E derivatives; Anti-cancer drug delivery;
Non-contact weight measurement of flat-faced pharmaceutical tablets using terahertz transmission pulse delay measurements by Prince Bawuah; Pertti Silfsten; Tuomas Ervasti; Jarkko Ketolainen; J. Axel Zeitler; Kai-Erik Peiponen (16-22).
Display OmittedBy measuring the time delay of a terahertz pulse traversing a tablet, and hence its effective refractive index, it is possible to non-invasively and non-destructively detect the weight of tablets made of microcrystalline cellulose (MCC). Two sets of MCC tablets were used in the study: Set A (training set) consisted of 13 tablets with nominally constant height but varying porosities, whereas Set B (test set) comprised of 21 tablets with nominally constant porosity but different heights. A linear correlation between the estimated absolute weight based on the terahertz measurement and the measured weight of both sets of MCC tablets was found. In addition, it was possible to estimate the height of the tablets by utilizing the estimated absolute weight and calculating the relative change of height of each tablet with respect to an ideal tablet. A good agreement between the experimental and the calculated results was found highlighting the potential of this technique for in-line sensing of the weight, porosity and the relative change in height of the tablets compared to a reference/ideal tablet. In this context, we propose a quantitative quality control method to assess the deviations in porosity of tablets immediately after compaction.
Keywords: Microcrystalline cellulose (MCC); Tablets; Terahertz spectroscopy; Effective refractive index; Tablet weight; Tablet height; Process analytical technology; High throughput technologies; Simulations; Compaction;
Anionic nanoparticles based on Span 80 as low-cost, simple and efficient non-viral gene-transfection systems by A. Pensado; I. Fernandez-Piñeiro; B. Seijo; A. Sanchez (23-30).
Display OmittedThe existing strategies in the design of non-viral vectors for gene therapy are primarily conceived for cationic systems. However, the safety concerns associated with the use of positively charged systems for nucleic acid delivery and several reports regarding the efficacy of negatively charged systems highlights the need for improved gene-delivery vectors. With these premises in mind, we investigated the development of new negatively charged nanoparticles based on Sorbitan esters (Span®) – extremely cheap excipients broadly used in the pharmaceutical industry – on the basis of a simple, one-step and easily scalable procedure. For their specific use in gene therapy, we have incorporated oleylamine (OA) or poly-l-arginine (PA) into these nanosystems. Thus, we used Sorbitan monooleate (Span® 80) to design Span® 80-oleylamine and Span® 80-poly-l-arginine nanosystems (SP–OA and SP–PA, respectively). These systems can associate with the model plasmid pEGFP-C3 and show mean particle sizes of 304 nm and 247 nm and surface charges of −13 mV and −17 mV, respectively.The nanoparticles developed were evaluated in terms of in vitro cell viability and transfection ability. Both systems exhibited an appropriate cell-toxicity profile and are able to transfect the plasmid effectively. Specifically, the nanosystems including OA among their components provided higher transfection levels than the SP–PA nanoparticles. In conclusion, anionic nanoparticles based on Span® 80 can be considered low-cost, simple and efficient non-viral anionic gene-transfection systems.
Keywords: Sorbitan esters; Span®; Oleylamine; Polyarginine; Gene therapy; Anionic nanoparticles;
Thermo-responsive release of curcumin from micelles prepared by self-assembly of amphiphilic P(NIPAAm-co-DMAAm)-b-PLLA-b-P(NIPAAm-co-DMAAm) triblock copolymers by Yanfei Hu; Vincent Darcos; Sophie Monge; Suming Li; Yang Zhou; Feng Su (31-40).
Display OmittedThermo-responsive micelles are prepared by self-assembly of amphiphilic triblock copolymers composed of a poly(l-lactide) (PLLA) central block and two poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) (P(NIPAAm-co-DMAAm)) lateral blocks, using solvent evaporation/film hydration method. The resulting micelles exhibit very low critical micelle concentration (CMC) which slightly increases from 0.0113 to 0.0144 mg mL−1 while the DMAAm content increases from 31.8 to 39.4% in the hydrophilic P(NIPAAm-co-DMAAm) blocks. The lower critical solution temperatures (LCST) of copolymers varies from 44.7 °C to 49.4 °C in water as determined by UV spectroscopy, and decreases by ca. 3.5 °C in phosphate buffered saline (PBS). Curcumin was encapsulated in the core of micelles. High drug loading up to 20% is obtained with high loading efficiency (>94%). The LCST of drug loaded micelles ranges from 37.5 to 38.0 °C with drug loading increasing from 6.0 to 20%. The micelles with diameters ranging from 47.5 to 88.2 nm remain stable over one month due to the negative surface charge as determined by zeta potential (−12.4 to −18.7 mV). Drug release studies were performed under in vitro conditions at 37 °C and 40 °C, i.e. below and above the LCST, respectively. Initial burst release is observed in all cases, followed by a slower release. The release rate is higher at 40 °C than that at 37 °C due to thermo-responsive release across the LCST. On the other hand, micelles with lower drug loading exhibit higher release rate than those with higher drug loading, which is assigned to the solubility effect. Peppas' theory was applied to describe the release behaviors. Moreover, the in vitro cytotoxicity of copolymers was evaluated using MTT assay. The results show that the copolymers present good cytocompatibility. Therefore, the nano-scale size, low CMC, high drug loading and stability, as well as good biocompatibility indicate that these thermo-responsive triblock copolymer micelles present a good potential as carrier for targeted delivery of anticancer drugs.
Keywords: Thermo-responsive; Micelle; Self-assembly; Poly(l-lactide); Poly(N-isopropylacrylamide); Curcumin;
Physicochemical characterization of sildenafil-loaded solid lipid nanoparticle dispersions (SLN) for pulmonary application by M. Paranjpe; J.H. Finke; C. Richter; T. Gothsch; A. Kwade; S. Büttgenbach; C.C. Müller-Goymann (41-49).
Display OmittedFor the development of any colloidal system, thorough characterization is extremely essential. This article discusses the physicochemical characterization of sildenafil-loaded solid lipid nanoparticle dispersions (SLN) including stability analysis over 6 months time period for possible pulmonary administration for the treatment of pulmonary arterial hypertension (PAH). SLN consisting of phospholipid and triglycerides were manufactured using a novel microchannel homogenization method. These sildenafil-loaded SLN were then subjected to physicochemical characterization namely, particle size and distribution over shelf life, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and analysis of nebulization performance of these SLN by the means of next generation impactor (NGI). Additionally, the morphology of nebulized particles was assessed by transmission electron microscopy using negative staining technique. The solubility of sildenafil citrate and base in the lipid matrix was determined and was 0.1% w/w and 1% w/w, respectively. From the particle size measurements, it was observed that SLN without sildenafil demonstrated consistent particle sizes over 6 months. For the sildenafil-loaded SLN, increased particle sizes were found after manufacturing and further increased within weeks. From WAXD studies, after 6 months high intensity reflections corresponding to the stable β modification were observed. From DSC results, the peak minimum temperatures increased upon storage, hinting at a transformation to the stable β modification of triglycerides in the case of sildenafil-loaded SLN. Hence, it can be concluded that even small drug concentration influences particle size and stability.
Keywords: Sildenafil; Solid lipid nanoparticles (SLN); Microchannel homogenization; Pulmonary administration; Physicochemical characterization; Next generation impactor (NGI);
Evaluation of etanercept stability as exposed to various sugars with biophysical assessment by Dae Gon Lim; Nam Ah Kim; Jun Yeul Lim; Ki Hyun Kim; Shavron Hada; Seong Hoon Jeong (50-59).
Display OmittedEven though sugars have been used widely as additives for protein formulations, their exact mechanisms of protein stabilization and applicability remain still in need of investigation. The main purpose of this study was to evaluate the effects of various sugars on the biophysical stability of etanercept (Enbrel®). Six well known sugars including glucose, fructose, maltose, sucrose, trehalose, and raffinose were incorporated into the protein solution with different concentrations. The samples were analyzed with dynamic light scattering (DLS), differential scanning calorimetry (DSC), circular dichroism (CD), and size-exclusion chromatography (SEC). The DLS measurement showed that as the number of simple sugars and solution concentration increased, the hydrodynamic size increased with a decreasing absolute zeta potential. The DSC result provided consistent trends with the DLS data. As the concentration of sugar increased, the protein transition temperature (Tm ) was gradually increased in most of samples. In addition, a non-enzymatic browning reaction (NEB) was observed during heating of the sugar solution. To monitor the storage stability, sample solutions were stored at 4 and 40 °C. At 4 °C, the ratio of monomer, aggregate, and fragment were not significantly changed. However, fragmentation of etanercept was observed in accelerated storage. In addition, fructose and maltose showed a peak shift in the SEC result. Those results suggest that the reducing ability of sugar might be a reason for the different etanercept degradation pathways. Therefore, sugars need to be carefully considered to achieve the maximum efficiency of therapeutic proteins for the development of protein formulations.
Keywords: Etanercept; Differential scanning calorimetry; Sugar; Fructose; Raffinose;
In vitro and in vivo evaluation of self-nanoemulsifying drug delivery systems of cilostazol for oral and parenteral administration by Dina B. Mahmoud; Marwa H. Shukr; Ehab R. Bendas (60-69).
Display OmittedThe current investigation was aimed to improve the solubility of poorly soluble drug, cilostazol (CLZ). Self-nanoemulsifying drug delivery system (SNEDDS) composed of oil, surfactant and co-surfactant for both oral and parenteral administration of CLZ was formulated. The components for SNEDDS were identified by solubility studies, and pseudo-ternary phase diagrams were plotted to identify the efficient self-emulsification regions. The optimum formula, composed of Capryol 90 as an oil phase, Cremophor EL as a surfactant, and Transcutol HP as a co-surfactant in a ratio of 19.8:30.5:49.7 by weight, was able to solubilize CLZ 2000 times higher than its solubility in water. This formula was able to form grade “A” nanoemulsion when diluted with water, resulted in emulsification time of 50 ± 1.1 s, particle size of 14.3 nm, PDI of 0.5 and % transmittance was 97.40% ± 0.65. It showed excellent in vitro dissolution of 93.1% and 81.5% after 5 min in 0.3% sodium lauryl sulphate solution and phosphate buffer pH 6.4, respectively when compared with the marketed tablet formulation and drug suspension as the tablets showed only 44.3% and 9.9% while CLZ suspension showed 33.9% and 8.8% in 0.3% sodium lauryl sulphate solution and phosphate buffer pH 6.4, respectively. It was found to be robust to dilution, thermodynamically stable with low viscosity values of 14.20 ± 0.35 cP. In vivo study revealed significant increase in bioavailability of CLZ in rabbits to 3.94 fold compared with the marketed tablet formulation after oral administration. This formula could be sterilized by autoclaving and did not cause significant hemolysis to human blood which indicates its safety for intravenous administration with a 1.12 fold increase in bioavailability compared with its oral administration. Our study illustrated the potential use of SNEDDS of poorly soluble CLZ orally, and its successful administration of parenterally when required in acute cases of myocardial and cerebral infarction.
Keywords: Cilostazol; Self-nanoemulsyfying systems; Pharmacokinetics; Oral administration; Intravenous administration;
Polymer brushes containing thermosensitive and functional groups grafted onto magnetic nano-particles for interaction and extraction of famotidine in biological samples by Homayon Ahmad Panahi; Sara Nasrollahi (70-76).
Display OmittedThis study introduces a new method for grafting poly[N-isopropylacrylamide-co-allyl glycidyl/iminodiacetic] onto iron oxide nano-particles modified using 3-mercaptopropyltrimethoxysilane. The grafted nano-polymer was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, transmission electron microscopy and scanning electron microscopy. The parameters of pH, contact time and temperature of the grafted nano-polymer were investigated. The determination and extraction of famotidine in human biological fluids was evaluated for high accessibility to active sites on the grafted sorbent. The equilibrium adsorption data were analyzed using the Langmuir and Freundlich models. The sorption capacity of the nano-sorbent was 116 mg g−1 at an optimum pH of 7. About 73% of famotidine was released into simulated gastric fluid by 1 h and 70% was released into simulated intestinal fluids by 30 h at 37 °C. These results show that this new magnetic grafted nano-polymer is suitable for enteric drug delivery.
Keywords: Famotidine; Human biological fluids; Solid phase extraction; Enteric drug delivery; Magnetic nano-particles;
Tablet subdivision: Far beyond the splitting technique by Jaqueline Kalleian Eserian; Márcia Lombardo (77).
Coatings from blends of Eudragit® RL and L55: A novel approach in pH-controlled drug release by R. Wulff; C.S. Leopold (78-87).
Display OmittedThe aim of the present study was to investigate the drug release from theophylline pellets coated with blends of quaternary polymethacrylate and methacrylic acid–ethyl acrylate copolymers. Pellets were coated with blends of Eudragit® RL PO (RL) and Eudragit® L 100-55 (L55) in either organic solution or aqueous dispersion at various copolymer ratios. Generally, the coatings were less permeable for theophylline in phosphate buffer pH 6.8 than they were in hydrochloric acid pH 1.2. Further dissolution experiments revealed that the differences in drug release are caused by the different pH values. A design of experiments for historical data was performed on drug release data of pellets with different coating levels and blend ratios of RL and L55. Drug release in hydrochloric acid was predominantly affected by the coating level, whereas for drug release in phosphate buffer pH 6.8 the blend ratio was the determining factor. As expected, dissolution experiments at different pH values showed that drug release depends on the ratio of dissociated L55 to RL because ionization is a requirement for the functional groups to interact. With the dissolution test for delayed-release solid dosage forms (Ph. Eur.) it was demonstrated that the unique release behavior in neutral media is preserved after the exposition to hydrochloric acid. These findings indicate that the combination of RL and L55 in coatings prepared from solutions is a promising approach for controlled drug release.
Keywords: Quaternary polymethacrylate; Interpolyelectrolyte complex; Response surface methodology; pH-dependent drug release; Controlled drug release; Polymer blend;
Fused-filament 3D printing (3DP) for fabrication of tablets by Alvaro Goyanes; Asma B.M. Buanz; Abdul W. Basit; Simon Gaisford (88-92).
Display OmittedThe use of fused-filament 3D printing (FF 3DP) to fabricate individual tablets is demonstrated. The technology permits the manufacture of tablets containing drug doses tailored to individual patients, or to fabrication of tablets with specific drug-release profiles. Commercially produced polyvinyl alcohol (PVA) filament was loaded with a model drug (fluorescein) by swelling of the polymer in ethanolic drug solution. A final drug-loading of 0.29% w/w was achieved. Tablets of PVA/fluorescein (10 mm diameter) were printed using a 3D printer. It was found that changing the degree of infill percentage in the printer software varied the weight and volume of the printed tablets. The tablets were mechanically strong and no significant thermal degradation of the active occurred during printing. Dissolution tests were conducted in modified Hank’s buffer. The results showed release profiles were dependent on the infill percentage used to print the tablet. The study indicates that FF 3DP has the potential to offer a new solution for fabricating personalized-dose medicines or unit dosage forms with controlled-release profiles. In addition, the low cost of FDM printers means the paradigm of extemporaneous or point-of-use manufacture of personalized-dose tablets is both feasible and attainable.
Keywords: 3D printing; Controlled-release; Fused filament printing; PVA; Fluorescein;
Controlling the chemical stability of a moisture-sensitive drug product through monitoring and identification of coating process microenvironment by Umesh Kestur; Preetanshu Pandey; Sherif Badawy; Judy Lin; Divyakant Desai (93-98).
Display OmittedThe objective of this work was to monitor and identify the impact of coating microenvironment, as measured by PyroButtons® data loggers, on the chemical stability of a moisture-sensitive drug molecule brivanib alaninate (BA). BA tablets were coated at two different scales (15 and 24 in pan). PyroButtons® data loggers were allowed to move freely within the tablet bed to record the temperature and relative humidity conditions of the tablet bed. The tablet moisture content at the end of the coating runs, and the rate of hydrolysis of the BA tablets based on HPLC analysis was found to be a function of the coating thermodynamic microenvironment. Wetter coating conditions resulted in tablets with higher water content and showed greater degradation upon storage. The coating process which yielded acceptable stability in a 15 in coater was transferred to a 24 in coater by maintaining similar tablet-bed relative humidity and temperature conditions. This was compared to a traditional scale-up approach where the environmental equivalency factor (EEF) was matched between scales during coating. The moisture content observed across the two scales indicated that maintaining a similar tablet-bed microenvironment ensured consistent results between scales.
Keywords: Coating; PyroButtons; Thermodynamics; Microenvironment; Water-activity; Chemical stability;
Dipeptide prodrug approach to evade efflux pumps and CYP3A4 metabolism of lopinavir by Mitesh Patel; Ye Sheng; Nanda K. Mandava; Dhananjay Pal; Ashim K. Mitra (99-107).
Display OmittedOral absorption of lopinavir (LPV) is limited due to P-glycoprotein (P-gp) and multidrug resistance-associated protein2 (MRP2) mediated efflux by intestinal epithelial cells. Moreover, LPV is extensively metabolized by CYP3A4 enzymes. In the present study, dipeptide prodrug approach was employed to circumvent efflux pumps (P-gp and MRP2) and CYP3A4 mediated metabolism of LPV. Valine–isoleucine–LPV (Val–Ile–LPV) was synthesized and identified by LCMS and NMR techniques. The extent of LPV and Val–Ile–LPV interactions with P-gp and MRP2 was studied by uptake and transport studies across MDCK–MDR1 and MDCK–MRP2 cells. To determine the metabolic stability, time and concentration dependent degradation study was performed in liver microsomes. Val–Ile–LPV exhibited significantly higher aqueous solubility relative to LPV. This prodrug generated higher stability under acidic pH. Val–Ile–LPV demonstrated significantly lower affinity toward P-gp and MRP2 relative to LPV. Transepithelial transport of Val–Ile–LPV was significantly higher in the absorptive direction (apical to basolateral) relative to LPV. Importantly, Val–Ile–LPV was recognized as an excellent substrate by peptide transporter. Moreover, Val–Ile–LPV displayed significantly higher metabolic stability relative to LPV. Results obtained from this study suggested that dipeptide prodrug approach is a viable option to elevate systemic levels of LPV following oral administration.
Keywords: Lopinavir; LPV; Dipeptide prodrug; Uptake; Transport; Permeability; P-gp; MRP2 and metabolism;
Increasing the stability of curcumin in serum with liposomes or hybrid drug-in-cyclodextrin-in-liposome systems: A comparative study by Ahmed H. Matloob; Spyridon Mourtas; Pavlos Klepetsanis; Sophia G. Antimisiaris (108-115).
Display OmittedCurcumin (CURC) was incorporated in liposomes as free drug or after formation of hydropropyl-β- or hydroxypropyl-γ-cyclodextrin (HPβCD or HPγCD) complexes prepared by coprecipitation and characterized by X-ray diffractometry. Liposomes encapsulating CURC as free drug or CD-complexes (hybrid formulations) were prepared by the dehydration–rehydration vesicle (DRV) method followed by extrusion, and characterized for size, zeta-potential and CURC loading. CURC stability (at 0.01 and 0.05 mg/mL) in 80% (v/v) fetal bovine serum (FBS) was evaluated at 37 °C. Results demonstrate that HPβCD stabilizes CURC more than HPγCD, but liposome encapsulation provides substantially more protection, than CDs. CURC stabilization is similar, when encapsulated as free compound or CD-complex. However, the last method increases CURC loading by 23 times (depending on the lipid composition of liposomes and the CD used), resulting in higher solubility. The stability profile of CURC in serum depends on the composition of liposomes and CURC concentration, since at lower concentrations larger CURC fractions are protected due to protein binding. Compared to the corresponding CD complexes, hybrid formulations provide intermediate CURC solubility (comparable to HPβCD) but profoundly higher stabilization.
Keywords: Curcumin; Liposome; Cyclodextrin; Inclusion complex; Stability; Serum;
A mesoporous silicon/poly-(dl-lactic-co-glycolic) acid microsphere for long time anti-tuberculosis drug delivery by Weikang Xu; Xinmiao Wei; Kun Wei; Xiaodong Cao; Shizhen Zhong (116-123).
Display OmittedIn this study, drug delivery systems for controlling release of hydrophobic anti-tuberculosis (TB) drug-rifampicin (RIF) or hydrophilic anti-TB drug-isoniazid (INH) from mesoporous silica (MS) were fabricated. The drug was first filled into the mesopores of MS particles, and then the drug-laden MS constructs were incorporated into the bulk of poly-(dl-lactic-co-glycolic) acid (PLGA) microspheres. In comparison with mono-component construct (drug-laden MS and drug-laden PLGA), this multi-component system significantly improved the release time of RIF and INH. For drug-laden MS, about 100% INH was released after 15 h, and about 70% RIF was released after 50 h. For drug-laden PLGA, about 100% INH and RIF were released after 30 and 40 days, respectively. After 60 days, the total RIF and INH release from MS/PLGA had only reached around only 48% and 57%, respectively. This MS/PLGA system could significantly prolong RIF or INH release compared to MS and PLGA. CCK-8 assay demonstrated that this MS/PLGA system had no cytotoxicity. And there has not been study of documenting the controlled release of anti-TB drugs such as RIF or INH from MS/PLGA. Considering the long time release of RIF and INH from MS/PLGA, a new door to bone TB would be opened.
Keywords: Mesoporous silica; PLGA; Prolong release; Rifampicin; Isoniazid;
Preparation, characteristics and assessment of a novel gelatin–chitosan sponge scaffold as skin tissue engineering material by Fei Han; Yang Dong; Zhen Su; Ran Yin; Aihua Song; Sanming Li (124-133).
The morphology of HSF cells in sponges at different time intervals evaluated by AO/BE staining method. (a) The morphology of HSF; (b) the morphology of sponge scaffold; (c) sponge cultured with HSF at the 3rd day; (d) sponge cultured with HSF at the 7th day; (e) sponge cultured with HSF at the 14th day, (f) sponge cultured with HSF at the 21st day; (g) the morphology of HaCat on Gel/Chs sponge scaffold containing HSF, S: sponge, H: HaCat.Display OmittedIn order to develop a skin tissue engineering material for wound dressing application, a novel gelatin–chitosan sponge scaffold was designed and studied. The effect of chitosan and gelatin ratio on the morphology, pore size, porosity, water uptake capacity, water retention capacity and the degradation behavior were evaluated. Biocompatibility was investigated by both MTT method and AO/EB staining method. Antibacterial assessment and in vivo pharmacodynamic was also studied to evaluate the potential for wound healing. Results showed the sponge scaffold have uniform porous structure with pore size range between 120 and 140 μm, high porosity (>90%), high water uptake capacity (>1500%), high water retention capacity (>400%), and degradation percent in 28 days between 38.3 and 53.9%. Biocompatibility results showed that the activity of cells could not be affected by the nature of the sponge and it was suitable for cell adhesion and proliferation for 21 days. In vivo evaluation indicated that the sponge scaffold could offer effective support and attachment to cells for skin wound healing. In conclusion, the developed sponge scaffold was a potential skin tissue engineering material with appropriate physical properties and good biocompatibility.
Keywords: Chitosan; Gelatin; Sponge scaffold; Skin tissue engineering; Biocompatibility;
Rhamnolipids as emulsifying agents for essential oil formulations: Antimicrobial effect against Candida albicans and methicillin-resistant Staphylococcus aureus by Ester Haba; Samira Bouhdid; Noelia Torrego-Solana; A.M. Marqués; M. José Espuny; M. José García-Celma; Angeles Manresa (134-141).
Display OmittedThis work examines the influence of essential oil composition on emulsification with rhamnolipids and their use as therapeutic antimicrobial agents against two opportunistic pathogens, methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans. Rhamnolipids, produced by Pseudomonas aeruginosa, with waste frying oil as the carbon source, were composed of eight rhamnolipid homologues. The rhamnolipid mixture was used to produce emulsions containing essential oils (EOs) of Melaleuca alternifolia, Cinnamomum verum, Origanum compactum and Lavandula angustifolia using the titration method. Ternary phase diagrams were designed to evaluate emulsion stability, which differed depending on the essential oil. The in vitro antimicrobial activity of the EOs alone and the emulsions was evaluated. The antimicrobial activity presented by the essential oils alone increased with emulsification. The surface properties of rhamnolipids contribute to the positive dispersion of EOs and thus increase their availability and antimicrobial activity against C. albicans and S. aureus. Therefore, rhamnolipid-based emulsions represent a promising approach to the development of EO delivery systems.
Keywords: Essential oils; Rhamnolipids; Emulsions; Phase behaviour; Methicillin-resistant;
Sustained release and enhanced bioavailability of injectable scutellarin-loaded bovine serum albumin nanoparticles by Yuanfeng Wei; Laicun Li; Yifeng Xi; Shuai Qian; Yuan Gao; Jianjun Zhang (142-148).
Display OmittedThe aim of this study is to characterize the in-vitro physicochemical and in-vivo pharmacokinetic properties of the scutellarin-loaded bovine serum albumin nanoparticles (STA-BSA-NPs). STA existed as amorphous form in the nanoparticles. Reconstituted STA-BSA-NPs had an average particle size of 283.4 nm and a zeta potential of +17.95 mV. The in-vitro sustained release profile was well fitted with Weibull distribution model. In comparison to STA solution, STA-BSA-NPs exhibited a significantly higher plasma concentration from 20 min to 6 h after intravenous administration to rats. In addition, significantly higher AUC0–inf (2.8-fold), prolonged elimination half-life (4.2-fold) and lower clearance (2.7-fold) were achieved.
Keywords: Scutellarin; Albumin nanoparticles; Sustained release; Elimination half-life; Bioavailability;
Visceral mesh modified with cyclodextrin for the local sustained delivery of ropivacaine by G. Vermet; S. Degoutin; F. Chai; M. Maton; M. Bria; C. Danel; H.F. Hildebrand; N. Blanchemain; B. Martel (149-159).
Display OmittedThe aim of the study was to develop a polyester visceral implant modified with a cyclodextrin polymer for the local and prolonged delivery of ropivacaine to reduce post operatory pain. Therefore, we applied a coating of an inguinal mesh with a crosslinked polymer of hydroxypropyl-β-cyclodextrin (HPβCD) whose specific host–guest complex forming properties were expected to improve the adsorption capacity of the implant toward anesthetic, and then to release it within a sustained period.The modification reaction of the textile with cyclodextrin was explored through the study of the influence of the pad/dry/cure process parameters and the resulting implant (PET–CD) was characterized by solid state NMR and SEM. Besides, the inclusion complex between ropivacaine and CD was studied by NMR and capillary electrophoresis in PBS medium. Finally, ropivacaine sorption test showed that a maximum of 30 mg/g of ropivacaine could be adsorbed on the functionalized samples. In dynamic batch tests in PBS at pH 7.4, the release could be observed up to 6 h. The cytocompatibility of the PET–CD loaded with ropivacaine was also studied and reached 65% cell vitality after 6 days.
Keywords: Surface modification; Visceral mesh textile; Cyclodextrin; Local anesthetic; Ropivacaine; Prolonged delivery;
Study of the persistence of the anti-inflammatory effect observed after application of preparations containing organic ultraviolet filters by C. Couteau; C. Chauvet; E. Paparis; L.J.M. Coiffard (160-163).
Persistence of the anti-inflammatory effect observed after application of preparations containing various ultraviolet filters authorized in EU.Display OmittedGiven that previous studies have highlighted the anti-inflammatory nature, which is influenced by UV radiation, of a certain number of ultraviolet filters currently used in Europe, it seemed interesting to evaluate the persistence of this type of effect. The persistence of the anti-inflammatory effect of fourteen preparations, each containing one of the ultraviolet filters authorized by Regulation (CE) No. 1223/2009, and of 10 commercially-available sun products was studied using the phorbol-myristate-acetate test on mice, up to 6 and a half hours after application. We can observe that a benzophenone, oxybenzone, a PABA derivative, octyldimethylPABA and a derivative of cinnamic acid, OMC as well as 3 commercially-available products, display a very marked anti-inflammatory effect at the end of our experimentation phase. The type of effect observed could encourage users to prolong the time that they are exposed to the sun, due to there being no warning signs, namely sunburn.
Keywords: Skin; Sun products; Anti-inflammatory effect; UV filters; Persistence of the effect;
Prolonged local retention of subcutaneously injected polymers monitored by noninvasive SPECT imaging by Chie Kojima; Yuichiro Niki; Mikako Ogawa; Yasuhiro Magata (164-168).
Display OmittedPolymers are widely applied to drug delivery systems because polymers are generally excreted from the body more slowly than small molecules. Subcutaneous injection is one plausible means of administration. In this study, the in vivo behaviors of subcutaneously injected polymers, linear poly(glutamic acid) (Poly-Glu), acetylated dendrimer (Ac-den) and collagen peptide-conjugated dendrimer (CP-den), were investigated. Single photon emission computed tomography (SPECT) imaging was used to noninvasively monitor the in vivo behaviors. Diethylenetriaminepentaacetic acid (DTPA) was conjugated to these polymers, which were labeled with radioactive 111In. These 111In-DTPA-bearing polymers (Poly-Glu–DTPA, Ac-den–DTPA and CP-den–DTPA) and unconjugated DTPA were subcutaneously injected into tumor-bearing mice, which were subjected to SPECT imaging. These 111In-DTPA-bearing polymers were largely retained at the injection site for at least 1 day, whereas the unconjugated DTPA was rapidly cleared from the whole body through excretion. Poly-Glu–DTPA and Ac-den–DTPA were partly accumulated in the kidney (and the liver), but the CP-den–DTPA was not. However, these 111In-DTPA-bearing polymers were accumulated in the liver and the kidney following intravenous administration. These results indicate that the subcutaneously injected polymers did not largely gain substantial access to the systemic circulation, which is useful for a depot of drug around the injection site.
Keywords: SPECT imaging; Subcutaneous injection; Polymer; Dendrimer; Poly(glutamic acid);
Nanostructured lipid carriers versus microemulsions for delivery of the poorly water-soluble drug luteolin by Ying Liu; Lan Wang; Yiqing Zhao; Man He; Xin Zhang; Mengmeng Niu; Nianping Feng (169-177).
Display OmittedNanostructured lipid carriers and microemulsions effectively deliver poorly water-soluble drugs. However, few studies have investigated their ability and difference in improving drug bioavailability, especially the factors contributed to the difference. Thus, this study was aimed at investigating their efficiency in bioavailability enhancement based on studying two key processes that occur in NLC and ME during traverse along the intestinal tract: the solubilization process and the intestinal permeability process.The nanostructured lipid carriers and microemulsions had the same composition except that the former were prepared with solid lipids and the latter with liquid lipids; both were evaluated for particle size and zeta potential. Transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction were performed to characterize their properties. Furthermore, in vitro drug release, in situ intestinal absorption, and in vitro lipolysis were studied. The bioavailability of luteolin delivered using nanostructured lipid carriers in rats was compared with that delivered using microemulsions and suspensions.The in vitro analysis revealed different release mechanisms for luteolin in nanostructured lipid carriers and microemulsions, although the in situ intestinal absorption was similar. The in vitro lipolysis data indicated that digestion speed and extent were higher for microemulsions than for nanostructured lipid carriers, and that more of the former partitioned to the aqueous phase. The in vivo bioavailability analysis in rats indicated that the oral absorption and bioavailability of luteolin delivered using nanostructured lipid carriers and microemulsions were higher than those of luteolin suspensions.Nanostructured lipid carriers and microemulsions improved luteolin’s oral bioavailability in rats. The rapid lipid digestion and much more drug solubilized available for absorption in microemulsions may contribute to better absorption and higher bioavailability.
Keywords: Nanostructured lipids carriers; Microemulsions; Luteolin; In situ intestinal absorption; In vitro lipolysis; Oral bioavailability;
β-Cyclodextrin/thermosensitive containing polymer brushes grafted onto magnetite nano-particles for extraction and determination of venlafaxine in biological and pharmaceutical samples by Homayon Ahmad Panahi; Haniyeh Sadat Alaei (178-184).
Display OmittedIn this paper, a novel nano-sorbent is fabricated by the surface grafting of poly[β-CD/allylamine-co-N-isopropylacrylamide] onto modified magnetite nano-particles by 3-mercaptopropyltrimethoxysilane. The polymer grafted magnetite nano-particles was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, scanning electron microscopy, and transmission electron microscopy. The feasibility of employing this nano-sorbent for extraction of trace venlafaxine in pharmaceutical samples and human biological fluids are investigated. The effect of various parameters such as pH, reaction temperature, and contact time was evaluated. The result revealed that the best sorption of venlafaxine by the magnetite nano-sorbent occurred at 35 °C at an optimum pH of 5. The kinetics of the venlafaxine shows accessibility of active sites in the grafted polymer onto the drug. The equilibrium data of venlafaxine by grafted magnetite nano-sorbent are well represented by the Langmuir and Freundlich isotherm models. The adsorption capacity of venlafaxine is found 142.8 mg g−1 and indicated the homogeneous sites onto polymer grafted magnetite nano-sorbent surface. Nearly 80% of venlafaxine was released in simulated intestinal fluid, pH 7.4, in 30 h and 90% in simulated gastric fluid, pH 1.2, in 1 h. The venlafaxine loaded-polymer grafted magnetite nano-particles were successfully applied for the extraction in urine and pharmaceutical samples.
Keywords: Venlafaxine; Drug delivery; Magnetite nano-particles; Solid phase extraction; Antidepressant; Pharmaceutical samples; Biological samples;
TPGS-g-PLGA/Pluronic F68 mixed micelles for tanshinone IIA delivery in cancer therapy by Jinming Zhang; Yingbo Li; Xiefan Fang; Demin Zhou; Yitao Wang; Meiwan Chen (185-198).
Display OmittedTanshinone IIA (TAN) has few clinical applications for anti-cancer therapy mainly due to its high lipophicity, low cellular uptake, and poor bioavailability. To improve the anti-cancer effect and bioavailability of TAN, we developed a mixed micelle system constituted with d-α-tocopheryl polyethylene glycol succinate-graft-poly(d,l-lactide-co-glycolide) (TPGS-g-PLGA) copolymer and Pluronic F68. TAN was encapsulated in the TPGS-g-PLGA/Pluronic F68 mixed micelles by using the thin film hydration technology optimized by the central composite design/response surface method (CCD/RSM). TAN-loaded mixed micelles were highly stable in the presence or absence of bovine serum albumin (BSA) and achieved sustained drug release in vitro. Compared with free TAN, TAN mixed micelles had higher cytotoxicity and pro-apoptotic effects against human hepatocellular carcinoma HepG2 cells. The significant enhancement on pro-apoptosis by TAN micelles was evidenced by increased chromosome condensation, mitochondria membrane potential loss, cell apoptosis, and cleavages of caspase-3 and PARP. Furthermore, pharmacokinetic studies revealed that TAN mixed micelles significantly prolonged the circulation time and improved bioavailability of TAN in rats. These results demonstrated that TAN-loaded TPGS-g-PLGA/F68 mixed micelles are an effective strategy to deliver TAN for cancer therapy.
Keywords: Mixed micelles; Tanshinone IIA; Apoptosis; Cancer therapy; TPGS; Pluronic F68;
TXA497 as a topical antibacterial agent: Comparative antistaphylococcal, skin deposition, and skin permeation studies with mupirocin by Mania Dorrani; Malvika Kaul; Ajit Parhi; Edmond J. LaVoie; Daniel S. Pilch; Bozena Michniak-Kohn (199-204).
Display OmittedTXA497 is representative of a new class of guanidinomethyl biaryl compounds that exhibit potent bactericidal behavior against methicillin-resistant Staphylococcus aureus (MRSA). In this study, we compared the anti-staphylococcal, skin deposition, and skin permeation properties of TXA497 and the topical anti-MRSA antibiotic mupirocin. The results of minimum inhibitory concentration (MIC) assays revealed that TXA497 retains potent activity against MRSA that is highly resistant to mupirocin. Using Franz diffusion cells, compound deposition into human cadaver skin was evaluated, and the results showed the skin deposition of TXA497 to be significantly greater than that of mupirocin. Moreover, unlike mupirocin, TXA497 does not pass through the entire skin layer, suggesting a minimal potential for the systemic absorption of the compound upon topical administration. Additionally, antibacterial concentrations of TXA497 showed no significant toxicity to primary human keratinocytes. Given the rising levels of mupirocin resistance among MRSA populations, our results are significant in that they highlight TXA497 as a potentially useful alternative therapy for treating MRSA skin infections that are resistant to mupirocin.
Keywords: TXA497; Mupirocin; MRSA; MSSA; Topical anti-bacterial; Skin permeation;
Influence of dose and animal species on accelerated blood clearance of PEGylated liposomal doxorubicin by Takuya Suzuki; Masako Ichihara; Kenji Hyodo; Eiichi Yamamoto; Tatsuhiro Ishida; Hiroshi Kiwada; Hiroshi Kikuchi; Hiroshi Ishihara (205-212).
Display OmittedWe recently demonstrated that Doxil loses its long-circulating properties when injected repeatedly at doses below 2 mg/m2 in dogs. In studies using other animal species, PEGylated liposomal doxorubicin has been reported not to induce the accelerated blood clearance (ABC) phenomenon. We investigated the issue of whether Doxil can elicit the ABC phenomenon in several species. In minipigs, the ABC phenomenon was induced at 2 mg/m2. In other animal species, the ABC phenomenon was not observed at higher doses (>2 mg/m2), but was observed at much lower doses (0.2 mg/m2). The pharmacokinetic profile of a second dose of Doxil reflected the circulating anti-PEG IgM level induced by the first dose. The ABC phenomenon was not observed at the clinically recommended DXR dose (20 mg/m2) in any animal species. These results indicate that Doxil can cause the ABC phenomenon in all animals tested, the extent of induction was dependent on the first dose of Doxil, and a higher Doxil dose lessened the ABC phenomenon. The current study results suggest that a careful study design including selection of animal species is important for preclinical studies using PEGylated liposomal formulations even if they contain anticancer drugs that suppress the host immune response.
Keywords: Polyethylene glycol; PEGylated liposomes; Accelerated blood clearance phenomenon; Doxorubicin; Doxil; Species difference;
Sustained release of antibiotic complexed by multivalent ion: In vitro and in vivo study for the treatment of peritonitis by Seung Yeon Na; Se Heang Oh; Tae Ho Kim; Jin A Yoon; In Soo Lee; Jin Ho Lee (213-222).
Display OmittedThe main aims of this study are (i) the development of an antibiotic complexed with multivalent ion, which can allow sustained release of the antibiotic without any additional matrix or difficult process and (ii) the feasibility study of the ion-complexed antibiotic as a therapeutic technique for peritonitis treatment. An ion-complexed antibiotic is prepared by simple mixing of two aqueous solutions containing an ionized (water-soluble) drug (tetracycline) and a multivalent counter ionic compound. The ion-complexed antibiotic shows a continuous release of the antibiotic up to 21 days, and thus prolonged anti-bacterial effect by gradual ionic exchange between the multivalent ions in the complex and same-charged monovalent ions in surrounding medium. From the in vivo animal study using a cecum perforated peritonitis mouse model, the ion-complexed antibiotic group shows sufficient anti-bacterial effect and thus effectively treat the peritonitis because of the extermination of the contaminated enteric bacteria in the peritoneum during wound healing of injury cecum (by the sustained release of antibiotic from the ion complex). These results suggest that the ion-complexed antibiotic system may be promising for the effective treatment of the peritonitis caused by frequent gastrointestinal defect in clinical fields.
Keywords: Peritonitis; Antibiotic; Ion complex; Sustained release;
Gastro-floating bilayer tablets for the sustained release of metformin and immediate release of pioglitazone: Preparation and in vitro/in vivo evaluation by Wei He; Yongji Li; Rao Zhang; Zhannan Wu; Lifang Yin (223-231).
Display OmittedOwing to the complementary mechanisms of action of metformin hydrochloride (MH) and pioglitazone hydrochloride (PG), combination therapy for type 2 diabetes mellitus using the two drugs is highly desired; on the other hand, MH is not well absorbed in lower gastrointestinal tract and has a short half-life, therefore compromising the therapeutic effects. Herein, the present study was to develop gastro-floating bilayer matrix tablets in which the two drugs were incorporated into two separate layers, aiming at sustaining MH release with enhanced absorption and achieving immediate release of PG. The tablets of the optimized formulation floated on the test medium for more than 24 h with 5 min of floating lag time, and sustained MH release for 12 h via a diffusion-dependent manner; and complete release of PG within 5 min were achieved. Moreover, a steady plasma concentration of MH with a 1.5-fold increase in bioavailability, decreased C max and reduced T max was obtained, and the in vivo behavior of PG was similar to the marked product. Summarily, sustained MH release with improved absorption and immediate release of PG were obtained simultaneously using the gastro-floating bilayer tablet, allowing strengthened combination therapy for diabetes mellitus.
Keywords: Metformin hydrochloride; Pioglitazone hydrochloride; Bilayer tablets; Floating drug delivery system; Pharmacokinetics; In vivo–in vitro correlation;
Injectable chitosan thermogels for sustained and localized delivery of pingyangmycin in vascular malformations by Fen Chen; Shuangshuang Song; Hongwei Wang; Wenji Zhang; Congcong Lin; Shilin Ma; Tiantian Ye; Ling Zhang; Xinggang Yang; Xingjun Qin; Weisan Pan (232-240).
Display OmittedPingyangmycin (PYM) is an effective drug to treat vascular malformations (VM), but can easily diffuse from the injection site, which will reduce its therapeutic effect and increase side effect. Our study was to evaluate PYM-loaded chitosan thermogels for sustained and localized embolization therapy. It was shown that in vitro release of PYM thermogels could be delayed up to 12 days. The results measured by MTT assay showed that PYM thermogels could inhibit proliferation and induce apoptosis of EA.hy926 cells in a concentration and time dependent manner. In vivo pharmacokinetics study demonstrated that compared with PYM injections, PYM thermogels had a better sustained delivery of PYM. Macroscopic observation and histological examination of rabbit ear veins displayed that after administration with PYM thermogels for 18 days, obvious venous embolization and inflammatory response could be found. These results indicate that PYM thermogels is likely to achieve excellent prospects for VM treatment.
Keywords: Pingyangmycin; Chitosan; Thermogels; Vascular malformations; Chemoembolization;
Construction of a two-in-one liposomal system (TWOLips) for tumor-targeted combination therapy by Tingting Su; Yingying Long; Chunyue Deng; Linglin Feng; Xiaolin Zhang; Zhangbao Chen; Chong Li (241-252).
Fabrication of RIV–TWOLips for dual targeting drug delivery to tumor cell and tumor neovasculature.Display OmittedIn oncology, there is a growing need for simpler, more selective methods to deliver drug therapies directly to the tumor site. For combination therapies, simultaneous targeted delivery of multiple drugs would represent a significant improvement. In contrast to previous work that took a de novo approach, we constructed a novel two-in-one liposomal system (TWOLips) from two single drug-loaded liposomes. Our results demonstrated that TWOLips could be prepared by a simple process, through silica coating of one liposome and incubation with the second liposome. TWOLips had a mean diameter of 100 nm, relatively high drug loading rates (96.8% ± 0.9% for doxorubicin and 78.4% ± 1.2% for combretastatin), and high storage stability. TWOLips modification by adding a targeting moiety, an all d-amino acid peptide derived from a natural vascular endothelial growth factor, resulted in strong, selective binding to vascular endothelial growth factor receptor 2, a tumorigenesis marker, in vitro and in vivo. TWOLips significantly inhibited tumor growth and angiogenesis and enhanced survival in mice with A375 melanoma xenografts. The TWOLips system had a low potential risk of toxicity. Since the stepwise assembly could be carried further (additional drug-loaded liposomes), TWOLips shows potential as a treatment for many cancers, especially those that require multiple drugs.
Keywords: Combination therapy; d-peptide; VEGFR2; Doxorubicin; Combretastatin A4;
Insights into the mechanisms of chitosan–anionic polymers-based matrix tablets for extended drug release by Liang Li; Linlin Wang; Jinfeng Li; Shan Jiang; Yitong Wang; Xin Zhang; Jiaojiao Ding; Tongya Yu; Shirui Mao (253-265).
Display OmittedThe aim of this study was to investigate drug release mechanisms from physical mixtures of chitosan–anionic polymers-based matrix tablets and to obtain a comprehensive understanding about release characteristics. Six types of anionic polymers (i.e., Eudragit® L100, sodium alginate, carrageenan, carboxymethylcellulose sodium, carbomer and xanthan gum) and two model drugs (i.e., theophylline and metoprolol succinate) with varied solubility were chosen. Texture analyzer, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were applied to better understand drug release mechanisms. In vitro release experiments were conducted in a pH-changing medium to simulate the physiological condition of the gastrointestinal tract. Interestingly, a common phenomenon was observed in all the CS–anionic polymers-based matrix tablets investigated here, that is, the inner layer of the swollen tablets was coated by CS–anionic polymer polyelectrolyte complexes (PEC)-based film formed by self-assembly. Formation of the in situ self-assembled film was further confirmed by texture analysis, DSC, and FTIR. It was further identified that properties of the film were influenced by the characteristics of anionic polymers and the physiological conditions of the gastrointestinal tract. Moreover, this novel structure could alter swelling and erosion-based release mechanisms of the tablets. In addition, drug release characteristics from CS–anionic polymer systems depended on the properties of anionic polymers and the drug solubility. In conclusion, our studies may broaden current views on cationic polymer–anionic polymer-based oral matrix tablets for extended release.
Keywords: Hydrophilic matrices; Matrix tablets; Chitosan; Anionic polymer; Oral controlled release/delivery; Polyelectrolyte complexes;
Effects of solvent on percutaneous absorption of nonvolatile lipophilic solute by Rattikorn Intarakumhaeng; S. Kevin Li (266-276).
Flux profiles of corticosterone across skin from solvents ethanol, hexane, propylene glycol (PG), polyethylene glycol 400 (PEG 400), butanol, isopropyl alcohol, and water.Display OmittedUnderstanding the effects of solvents upon percutaneous absorption can improve drug delivery across skin and allow better risk assessment of toxic compound exposure. The objective of the present study was to examine the effects of solvents upon the deposition of a moderately lipophilic solute at a low dose in the stratum corneum (SC) that could influence skin absorption of the solute after topical application. Skin permeation experiments were performed using Franz diffusion cells and human epidermal membrane (HEM). Radiolabeled corticosterone (3H-CS) was the model permeant. The solvents used had different evaporation and skin penetration properties that were expected to impact skin deposition of CS and its absorption across skin. The results show no correlation between the rate of absorption of the permeant and the rate of solvent evaporation/penetration with ethanol, hexane, isopropanol, and butanol as the solvent; all of these solvents have fast evaporation rates (complete evaporation in <30 min after application). This suggests no differences in solvent-induced deposition of CS in the SC for the fast-evaporating solvents. The results of these fast-evaporating solvents were different from those of water, propylene glycol, and polyethylene glycol 400, that a relationship between permeant absorption and the rate of solvent evaporation was observed.
Keywords: Skin; Percutaneous; Solvent; Absorption; Evaporation; Transdermal;
Engineering of nano-crystalline drug suspensions: Employing a physico-chemistry based stabilizer selection methodology or approach by Mostafa Nakach; Jean-René Authelin; Tharwat Tadros; Laurence Galet; Alain Chamayou (277-288).
Display OmittedThis paper describes a systematic approach to select optimum stabilizer for the preparation of nano-crystalline suspensions of an active pharmaceutical ingredient (API). The stabilizer can be either a dispersant or a combination of dispersant and wetting agent. The proposed screening method is a quick and efficient way to investigate a large number of stabilizers based on the principles of physical-chemistry and employs a stepwise approach. The methodology has been divided in two main parts; the first part being focused on the qualitative screening with the objective of selecting the best candidate(s) for further investigation, the second part has been focused on quantitative screening with the objective to optimize the ratio and amount of wetting and dispersing agents, based on wettability, surface charges measurement, adsorption evaluation, process-ability evaluation and storage stability.The results showed clearly that SDS/PVP 40/60% (w/w) (sodium dodecyl sulfate/poly(vinyl pyrrolidone)) at a total concentration of 1.2% was the optimum stabilizer composition, at which the resulting nanosuspensions were stable for more than 50 days at room temperature.
Keywords: Top down process; Nano-crystalline suspension; Beads milling; Stabilizer; Wetting agent; Dispersant agent;
Sequential intravenous injection of anionic polymer and cationic lipoplex of siRNA could effectively deliver siRNA to the liver by Yoshiyuki Hattori; Shohei Arai; Ryou Okamoto; Megumi Hamada; Kumi Kawano; Etsuo Yonemochi (289-298).
Display OmittedIn this study, we developed novel siRNA transfer method to the liver by sequential intravenous injection of anionic polymer and cationic liposome/cholesterol-modified siRNA complex (cationic lipoplex). When cationic lipoplex was intravenously injected into mice, the accumulation of siRNA was mainly observed in the lungs. In contrast, when cationic lipoplex was intravenously injected at 1 min after intravenous injection of poly-l-glutamic acid (PGA) or chondroitin sulfate C (CS), siRNA was accumulated in the liver. In terms of suppression of gene expression in vivo, apolipoprotein B (ApoB) mRNA in the liver and low-density-lipoprotein (LDL) and very low-density-lipoprotein (VLDL) cholesterol level in serum were reduced at 48 h after single sequential injection of PGA or CS plus cationic lipoplex of cholesterol-modified ApoB siRNA. Furthermore, sequential injections of PGA plus cationic lipoplex of cholesterol-modified luciferase siRNA could reduce luciferase activity in tumor xenografts bearing liver metastasis of human breast tumor MCF-7-Luc. From these findings, sequential injection of anionic polymer and cationic lipoplex of siRNA might produce a systemic vector of siRNA to the liver.
Keywords: Liposome; Anionic polymer; siRNA delivery; Chondroitin sulfate; Poly-l-glutamic acid;