Biomedical subjects

N H Parikh

Publications and source records attributed to N H Parikh.

9 recordsLinked to original sources

PubMed2002

Effect of drug proportion and mixing time on the content uniformity of a low dose drug in a high shear mixer.

The purpose of this study was to investigate the effect of reducing drug proportion and mixing time on the content uniformity of a low dose drug. Buspirone hydrochloride was used as a model drug and was mixed with other ingredients in two different concentrations (0.5% w/w and 5% w/w) in a T. K. Fielder high shear mixer at a high impeller speed (522 rpm) and a high chopper speed (3600 rpm) up to 32 min. Samples were withdrawn from nine locations in the mixer at specific time points using a side-sampling thief probe. The final blends at 32 min were compressed using an instrumented tablet press. Tablets were sampled at the beginning, middle, and end of the compression run. The statistical results indicated that the drug proportion had a significant effect on the content uniformity of the powder blend and the corresponding tablets. For this study, the optimum time to mix the 0.5% w/w formulation was after 8 min while it was only 1 min for the 5% w/w formulation. The RSD of buspirone hydrochloride contents of tablets decreased as the compression run was toward its end. Uniformly mixed blends produced tablets that met the USP XXIV content uniformity requirements.

Analysis of Variance↗

PubMed1993

Aqueous ethylcellulose dispersion of ethylcellulose. I. Evaluation of coating process variables.

Formulation and process variables play an important role in the film-forming properties of coating polymers. Three selected independent coating process variables, namely, percent solids content in the coating polymeric dispersion, inlet-air temperature, and spray rate of the polymeric dispersion, were investigated in this study to determine their effect on the performance characteristics of tablets coated with a plasticized aqueous ethylcellulose dispersion (Sure-lease) in a fluid-bed equipment. Response surface methodology (RSM) was utilized to study the complex relationship between these process variables and selected response variables. Three response variables were considered, namely, rate of drug release from the "untreated" coated tablets and the "thermal-treated" coated tablets and microindentation hardness of the untreated coated tablets. A 12-point factorial experimental design was utilized, and three-dimensional (3-D) response surface plots were generated using a second-order polynomial model. The model provided information needed to predict optimal process conditions. Drug release from the coated tablets followed zero-order kinetics. Inlet-air temperature was found to be the most critical process variable for all the three response variables studied. A correlation was observed between the drug release rate and the microindentation hardness of the applied polymeric coat in the case of untreated coated tablets. The 3-D response surface plots indicated that lower rates of drug release from the coated tablets may be obtained by using high inlet-air temperature and low spray rate of the polymeric dispersion during coating.

Cellulose↗

PubMed1993

Tensile properties of free films cast from aqueous ethylcellulose dispersions.

Free films of two commercially available formulations of aqueous ethylcellulose dispersion differing only in plasticizer content (Sure-lease/E-7-7050 without silica and E-7-7060 containing dibutyl sebacate and glyceryl tricaprylate/caprate as plasticizers, respectively) were cast and coalesced at temperatures ranging between 30 and 70 degrees C. Mechanical properties of these films were measured using tensile stress analysis. Three mechanical parameters, namely, tensile strength, work of failure, and elastic modulus, were computed from the load-time profiles of these films. The results showed that the tensile strength and elastic modulus values of the films cast from both formulations increased with the corresponding increase in coalescence temperature up to 60 degrees C, beyond which no significant differences were observed. In the case of work of failure, however, the difference between the two formulations was observed above 60 degrees C. The films cast from Surelease/E-7-7050 formulation without silica (dibutyl sebacate as the plasticizer) were relatively softer than those from Surelease/E-7-7060 formulation (glyceryl tricaprylate/caprate as the plasticizer). At coalescence temperatures above 50 degrees C, the films cast from both formulations exhibited temperature-dependent plastic deformation.

Cellulose↗

PubMed1985