STABILITY STUDIES AND INFLUENCE OF A LOW-FAT MEAL ON THE PHARMACOKINETIC AND BIOAVAILABILITY OF NIFEDIPINE IN HEALTHY VOLUNTEERS

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Date
1991-09
Authors
SUNDAY, OLAWALE OKENIYI
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Abstract
Identification tests for nifedipine based on the thin-layer chromatography and melting point were carried out on the three brands of nifedipine employed in this study as specified in the B.P. (1988) addendum (1990). The results obtained were in conformity with the B.P. 1988 specifications under identification tests for nifedipine. The presence of nifedipine in the tablets was examined by running the ultra-violet absorption spectrum of the reference nifedipine and comparing it with the U.V. spectra of the three brands of nifedipine samples. The spectra exhibited maxima which were at the same wavelength. HPLC and UV methods of chemical assay were also employed to determine the total drug content for the three brands. The results complied favourably with the stated amount in the B.P. 1988 for nifedipine content (98.00 - 102.0C%). The influence of day-light, fluorescent light, red-light, temperature and ultraviolet irradiation on the stability of nifedipine tablets and solution was evaluated. HPLC method for estimating drug content in tablet dosage forms was employed. Stability test of nifedipine solution in methanol showed loss of drug content and decomposition when exposed to day-light, fluorescent and ultraviolet irradiation while there was no significant decomposition nor loss of drug content under red-light and elevated temperature up to 50 C. Stability test carried out on nifedipine tablets showed no loss of drug content, decomposition nor colour change, indicating the stability of nifedipine tablets under all the conditions of irradiation. Dissolution rate profiles of three different brands of nifedipine tablets in 0.1M methanolic-hydrochloric acid was ingestigated by means of B.P. 1988 rotating basket method. The drugs showed similarities in their respective dissolution rate profiles. Total release of the active ingredient for the three brands was obtained in less than 30 minutes. Disintegration time test was carried out on the three brands of nifedipine tablets (S, 0, and K). There was no considerable variation in their disintegration times. The times taken for the three brands to disintegrate was less than 8 minutes. They all passed the official requirement of 15 minutes for tablet disintegration. Invivo bioavailability studies was carried out in healthy human subjects in fasting and non-fasting states. A simple, reliable and rapid HPLC method of nifedipine estimation proceeded by an extraction technique was employed for the determination of plasma and saliva nifedipine levels, pharmacokinetic parameters for plasma and saliva nifedipine samples were generated by computer application.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF MASTER OF SCIENCE IN PHARMACEUTICAL CHEMISTRY. DEPARTMENT OF PHARMACEUTICAL AND MEDICINAL CHEMISTRY, FACULTY OF PHARMACEUTICAL SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA. SEPTEMBER, 1991.
Keywords
STABILITY STUDIES,, INFLUENCE,, LOW-FAT MEAL,, PHARMACOKINETIC,, BIOAVAILABILITY,, NIFEDIPINE,, HEALTHY VOLUNTEERS
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