Sudip K. Das

Evaluation of Poly(isobutylcyanoacrylate) Nanoparticles for Mucoadhesive Ocular Drug Delivery. I. Effect of Formulation Variables on Physicochemical Characteristics of Nanoparticles

A factorial design was applied to evaluate the effect of formulation variables on physicochemical properties of poly(isobutylcyanoacrylate) nanoparticles. Formulation variables were dextran T40 or T70 and Pluronic™ F68 or Tween™ 20 acting as stabilizer and surfactant respectively, and three pH levels (2, 4 and 7). Nanoparticles possessed unimodal particle size distribution with significant effect of dextran, surfactant and pH. A wide range of molecular weight distribution was observed with significant effect of pH and dextran on average molecular weight. NMR studies revealed the presence of dextran, monomer and surfactants in the nanoparticles. Solid state surface analysis using X-ray photoelectron spectroscopy confirmed the presence of three chemical environments to the carbon envelope, O – C = O,C – O/C≡N and C – C.

Simulation of Physiological pH - Time Profile in In Vitro Dissolution Study: Relationship Between Dissolution Rate and Bioavailability of Controlled Release Dosage Form

AbstractAn in vitro batch dissolution method, simulating the in vivo pH-time profile was developed, using the USP XX dissolution apparatus. Significant correlation between in vitro dissolution data and bioavailability of the drug from the controlled release dosage form was obtained.

In Vitro Dissolution Profile of Theophvlline Lorded Ethvl Cellulose Microspheres Preprred by Emulsificrtion Soluent Eurporrtion

AbstractTheophylline was entrapped in ethyl cellulose microspheres by a water/oil/water emulsification-solvent evaporation method. Aqueous solution of drug was emulsified into a solution of ethyl cellulose in toluene, containing polyisobutylene as protective colloid, followed by emulsification of this primary emulsion into an external aqueous phase to form a water/oil/water emulsion. Microspheres was formed after solvent evaporation and precipitation of ethyl cellulose. In vitro dissolution profile and effect of polyisobutylene on it were studied.

Effect of Formulation Variables on the Preparation and in Vitro-in Vivo evaluation of Cimetidine Release from Ethyl Cellulose Micropellets

AbstractEthyl cellulose embedded prolonged release microparticles containing cimetidine was designed by dispersing the drug-ethyl cellulose mixture in acetone, into a medium of mineral oil and subsequent rigidization of the ethyl cellulose matrix. Significant reproducibility of the manufacturing process was observed. In vitro-in vivo correlation revealed the the dissolution process is the rate determining step in drug absorption and the significant in vivo efficiency of the dosage form is well expected.

Optimization of Controlled Drug Release Through Micropelletization

AbstractMicropelletization technique using crosslinked gelatin matrix was chosen to evaluate its utility in controlled release medications. Trimethoprim, which has a very high solubility gradient in gastric pH, was selected in this investigation. Micropellets were formed by the modified spray congealing technique. The effects of exposure of the crosslinking agents to the gelatin matrix of the micropellets on the effectivity as the controlled release drug delivery system were investigated. The total product yield, content uniformity and the reproducibilty of the sucessive batches were decidedly superior to either the pure drug or the non-crosslinked ones. Particle size distribution was observed to vary depending on the content of the crosslinked gelatin in the micropellets. Scanning electron micrographs confirmed the porous surface topography of the micropellets. The drug release characteristics was suggested as the diffusion controlled first order dissolution process.

Design and in Vitro Evaluation of Dapsone-Loaded Micropellets of Ethyl Cellulose

A controlled-release dosage form was manufactured by dispersing ethyl cellulose sol in acetone into a medium of mineral oil. Dapsone was used as the model drug. The powdered drug was dispersed in the ethyl cellulose sol, and the formulation variables affecting the production of the discrete and spherical micropellets and their size distribution were investigated. The percentage of SPAN 80 in the formulation affected the yield and physical properties of the micropellets. The in vitro drug release followed first-order diffusion-controlled dissolution. More than 85% of the drug was released over 5 hr for all formulation batches, with delayed release over the drug dissolution profile.

Design and in vitro evaluation of polyvinyl chloride microcapsules containing sulphamethoxazole

Polyvinyl chloride microcapsules containing sulphamethoxazole have been prepared by phase separation coacervation in non-aqueous solvents. Phase separation of the polyvinyl chloride in the solution of chloroform was achieved with n-hexane. Scanning electron micrographs revealed uniform encapsulation of the sulphamethoxazole particles. In vitro dissolution studies were conducted under changing pH conditions. The reproducibility of the in vitro drug release was highly significant. The mechanism of drug release was suggested as an integrated process of diffusion controlled dissolution. Controlled drug release was obtained over a prolonged period of 8 h.

Preparation and in Vitro Evaluation of Controlled Release Dosage form of Indomethacin

AbstractA controlled release oral drug delivery system of Indomethacin was developed using gelatin as the matrix system, which was rigidized with different concentrations of formalin, without using alcohol. The proportion of drug and gelatin as well as the concentration of formalin had the pronounced effect on the Indomethacin release rate and the patterns of which depicted that they correlated with Lang primary requirements for drug release from controlled release dosage forms. All the types of formulations showed release rate patterns that could best be described by First Order Kinetics, indicating that First Order release was mainly operative.

Design and in Vitro Evaluation of a Controlled Release Drug Delivery System of Sulfasomidine

AbstractA controlled release oral drug delivery system of Sulfasomidine was developed by spray congealing micropelleting technique using gelatin as the embedding matrix. The pellets were hardened by treating with Formalin-Isopropanol mixture. The in vitro release rate studies of Sulfasomidine from the micropelleted dosage form, revealed that the drug release can be prolonged upto eight hours and not more than 39% of the embedded drug released in the first hour of the in vitro dissolution study. The in vitro release patterns correlated with the reported in vivo studies. The method of formulation was optimized.

Controlled Theophylline Release from Microcapsules of Acrylic & Methacrylic Acid Ester Copolymer

AbstractThe goal of this work was to develop a suitable method for microencapsulation of theophylline using copolymer of acrylate and methacrylate ester (EUDRAGIT) as the coating material. The effect of protective colloids on the process of microencapsulation was evaluated. The in vitro studies revealed significant control of drug release for the developed dosage form. Individually, the polymer coated drug particles of different core: coat ratio and different proportions of protective colloids were found to influence the pharmacokinetic parameters as revealed from the in vivo bioavailability studies in gastric-emptying controlled rabbits. In vivo bioavailability data were compared using Westlakes confidence limit.