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Vitro Release Profiles (vitro + release_profile)
Selected AbstractsBiphasic Resorbable Calcium Phosphate Ceramic for Bone Implants and Local Alendronate Delivery,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Shashwat S. Banerjee A novel biphasic calcium phosphate ceramic composed of tricalcium phosphate (TCP) and calcium pyrophosphate (CP) is synthesized in order to tailor the biodegradation behavior of the ceramic. The results show that biphasic TCP/CP ceramic has a strength of 62.2,±,2.1 MPa, which is superior to single-phase TCP and CP ceramics, which show strengths of 44.3,±,3.0 and 53.0,±,4.8 MPa, respectively. In addition, biphasic TCP/CP ceramic displays a controlled strength degradation from 62.2,±,2.1 to 40.5,±,1.0 MPa in stimulated body fluid over a period of 28 d. An in vitro cell materials interaction study using human fetal osteoblast cells indicates that TCP/CP ceramic is cytocompatible. TCP/CP ceramic also show a good loading capacity for alendronate. Adsorption of alendronate (AD) on the TCP/CP surface is found to proceed via ligand exchange mechanism and the in vitro release profile of AD from TCP/CP surface is characterized by an initial fast release followed by a slow and sustained release. Strong electrostatic interactions between AD groups and surface Ca2+ ions enable the slow and sustained release of AD. These results demonstrate that the newly developed biphasic ceramic, with its controlled strength degradation and drug release, shows promise for use in orthopedic and tissue engineering applications. [source] Acrylate terpolymer in fabrication of medicated skin patchesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2001Vibha S. Mare Abstract An acrylate based pressure sensitive adhesive (PSA) was synthesized to design a drug-in-adhesive (DIA) type transdermal therapeutic system (TTS) for nitroglycerin used in the treatment of angina pectoris. 2-Ethylhexyl acrylate (EHA), methyl methacrylate (MMA) and acrylic acid (AA) were used to synthesize the PSA by free radical solution polymerization. The effects of reaction time, reaction temperature, initiator concentration and solvent on polymerization were studied. The synthesized terpolymer was characterized by 1H-NMR, FT-IR, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) and also evaluated for intrinsic viscosity, refractive index, peel strength, moisture uptake and skin irritation potential. The PSA was used to develop DIA type patches of nitroglycerin. The patches were cast using solvent evaporation technique and dried at controlled temperature. The patches were evaluated for thickness uniformity, weight variation, peel strength and moisture pick-up. The percent drug content and in vitro drug release was determined by high pressure liquid chromatography (HPLC) method. On the basis of in vitro release profile, patches were selected for in vitro skin permeation studies. The developed formulation TP-1 (K,=,24.892 mcg/cm2/hr) followed zero-order rate kinetics and showed better skin permeation rate in comparison to the marketed TTS (MTTS) (K,=,17.413 mcg/cm2/hr). TP-1 was subjected to stability testing for a period of 1 year according to ICH guidelines. The patches were found to be stable and an expiry date of 2 years was predicted with storage at 25,°C or below. Copyright © 2001 John Wiley & Sons, Ltd. [source] Chitosan-based interpolymeric pH-responsive hydrogels for in vitro drug releaseJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007M. Y. Abdelaal Abstract Two series of pH-responsive biodegradable interpolymeric (IPN) hydrogels based on chitosan (Ch) and poly(vinyl alcohol) (PVA) were prepared for controlled drug release investigations. The first series was chemically crosslinked with different concentrations of glutaraldehyde and the second was crosslinked upon ,-irradiation by different doses. The equilibrium swelling characteristics were investigated for the gels at 37°C in buffer solutions of pH 2.1 and 7.4 as simulated gastric and intestinal fluids, respectively. 5-Fluorouracil (FU) was entrapped in the hydrogels, as a model therapeutic agent, and the in vitro release profiles of the drug were established at 37°C in pH 2.1 and 7.4. FTIR, SEM, and X-ray diffraction analyses were used to characterize and investigate the structural changes of the gels with the variation of the blend composition and crosslinker content before and after the drug loading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2864,2874, 2007 [source] Characterization of pegylated copolymeric micelles and in vivo pharmacokinetics and biodistribution studiesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006Wen-Jen Lin Abstract The aim of this study was to evaluate the influence of pegylated copolymeric micelle carrier on the biodistribution of drug in rats. The copolymers were synthesized via a modified ring-opening copolymerization of lactone monomers (,-caprolactone, ,-valerolactone, L -lactide) and poly(ethylene glycol) (PEG10,000 and PEG4000). The molecular weights and the polydispersities of synthesized copolymers were in the range of 15,000,31,000 g/mol and 1.7,2.7, respectively. All of the pegylated amphiphilic copolymers were micelles formed with low CMC values in the range of 10,7,10,8M. The drug-loaded micelles were prepared via a dialysis method. The average particle size of micelles was around 150,200 nm. The cytotoxicity in terms of cell viability after treated with PCL,PEG, PVL,PEG, and PLA,PEG micelles was insignificant. PCL,PEG and PVL,PEG micelles without branch side chain in structures had higher drug loading than PLA,PEG micelles. In vitro release profiles indicated the release of indomethacin from these micelles exhibited a sustained release behavior. The similar phenomenon was also observed in vivo in rats. The pegylated copolymeric micelles not only decreased drug uptake by the liver and kidney, but also prolonged drug retention in the blood. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Preparation, physiochemical characterization, and oral immunogenicity of A,(1,12), A,(29,40), and A,(1,42) loaded PLG microparticles formulationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2009R. Rajkannan Abstract Alzheimer's disease (AD) is caused by the deposition of ,-amyloid (A,) protein in brain. The current AD immunotherapy aims to prevent A, plaque deposition and enhance its degradation in the brain. In this work, the peptides B-cell epitope A,(1,12), T-cell epitope A,(29,40) and full-length A,(1,42) were loaded separately to the poly (D,L -lactide co-glycolide) (PLG) microparticles by using W/O/W double emulsion solvent evaporation method with entrapment efficacy of 70.46%, 60.93%, and 65.98%, respectively. The prepared A, PLG microparticles were smooth, spherical, individual, and nonporous in nature with diameters ranging from 2 to 12 µm. The cumulative in vitro release profiles of A,(1,12), A,(29,40), and A,(1,42) from PLG microparticles sustained for long periods and progressively reached to 73.89%, 69.29%, and 70.08% by week 15. In vitro degradation studies showed that the PLG microparticles maintained the surface integrity up to week 8 and eroded completely by week 16. Oral immunization of A, peptides loaded microparticles in mice elicited stronger immune response by inducing anti-A, antibodies for prolonged time (24 weeks). The physicochemical characterization and immunogenic potency of A, peptides incorporated PLG microparticles suggest that the microparticles formulation of A, can be a potential oral AD vaccine. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:2027,2039, 2009 [source] Acitretin and treatment of the oral leucoplakias.JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 6 2000A model to have an active molecules release Abstract Aims The aim of this study was to investigate the effectiveness of acitretin in a new topical formulation (mucoadhesive two-layer tablets) for the treatment of oral leucoplakias. Methods Twenty-one volunteers, 16 men, five women, with oral leucoplakia (histologically diagnosed), were included in this double-blind placebo-controlled study. Patients were randomized in three groups (A, B, C) of seven patients each. Groups A and B received tablets with different in vitro release profiles, and group C subjects (controls) received tablets without acitretin. The acitretin dose was 20 mg/day (two 10 mg tablets daily). Serum aspartate aminotransferase, alanine aminotransferase, cholesterol and triglycerides were evaluated before and after treatment. At the end of therapy the concentrations of acitretin in plasma, saliva and tissue were measured by high-performance liquid chromatography. Results At the end of the study 71% (groups A and B) of patients showed clinical remission or marked improvement. No improvement was noted in the control subjects (group C). These results were further confirmed by histological findings. There were no significant changes in laboratory values in the three groups. The acitretin concentration in plasma and tissue ranged from 0 to 50 mg with no difference between groups A and B, and it was very high in saliva (ranging from 4.9 to 43 mg) with higher concentrations in group A than in group B (due to a longer adhesion time in group A). Patients' compliance was excellent. The results show that mucoadhesive tablets of topical acitretin are efficacious in the treatment of oral leucoplakia without systemic side-effects. [source] A Novel Technique for Loading of Paclitaxel-PLGA Nanoparticles onto ePTFE Vascular GraftsBIOTECHNOLOGY PROGRESS, Issue 3 2007Hyun Jung Lim The major cause of hemodialysis vascular access dysfunction (HVAD) is the occurrence of stenosis followed by thrombosis at venous anastomosis sites due to the aggressive development of venous neointimal hyperplasia. Local delivery of antiproliferative drugs may be effective in inhibiting hyperplasia without causing systemic side effects. We have previously demonstrated that paclitaxel-coated expanded poly(tetrafluoroethylene) (ePTFE) grafts, by a dipping method, could prevent neointimal hyperplasia and stenosis of arteriovenous (AV) hemodialysis grafts, especially at the graft-venous anastomoses; however, large quntities of initial burst release have remained a problem. To achieve controlled drug release, paclitaxel (Ptx)-loaded poly(lactic- co -glycolic acid) (PLGA) nanoparticles (Ptx-PLGA-NPs) were prepared by the emulsion-solvent evaporation method and then transferred to the luminal surface and inner part of ePTFE vascular grafts through our micro tube pumping and spin penetration techniques. Scanning electron microscope (SEM) images of various stages of Ptx-PLGA-NPs unequivocally showed that micro tube pumping followed by spin penetration effectively transferred Ptx-PLGA-NPs to the inner part, as well as the luminal surface, of an ePTFE graft. In addition, the in vitro release profiles of paclitaxel demonstrated that this new system achieved controlled drug delivery with a reduced initial burst release. These results suggest that loading of Ptx-PLGA-NPs to the luminal surface and the inner part of an ePTFE graft is a promising strategy to ultimately inhibit the development of venous neointimal hyperplasia. [source] | ||||||||||