Abstract
This research evaluated the physicochemical equivalence of some samples of Nifedipine 20 mg Retard Tablets available in Nigeria. Seven samples were randomly procured from various zones of the country and standard protocols applied to evaluate their tablet weight uniformity, dimensions, hardness, disintegration time, content of active Ingredient and in vitro drug release profile. Results showed that all the samples tested were chemically, but not physically equivalent. Although within each sample, compendial requirement for tablet weight uniformity was met, there were significant differences in the mean tablet weights, diameters and thickness of the samples studied (p < 0.05). Furthermore, tablet hardness and disintegration time varied much among the samples, but not within each sample. All the samples met the compendial requirement for content of active ingredient and released more than 80% of the drug within 4 h. It is therefore pertinent that manufacturers of this product be advised to formulate tablets that are equivalent in size, as different tablet sizes may impart negative psychological effects on clinicians and their patients when the need arises for switch over from one product to another, since the availability of particular products is never guaranteed at all times in Nigeria, a largely import dependent nation. Key words: Nifedipine 20 mg Retard tablets, physicochemical equivalence, in-vitrodrug release.
Highlights
In Nigeria, all the brands of Nifedipine 20 mg retard tablets available in the market, except one, are imported
This research evaluated the physicochemical equivalence of some samples of Nifedipine 20 mg Retard Tablets available in Nigeria
Seven samples were randomly procured from various zones of the country and standard protocols applied to evaluate their tablet weight uniformity, dimensions, hardness, disintegration time, content of active Ingredient and in vitro drug release profile
Summary
In Nigeria, all the brands of Nifedipine 20 mg retard tablets available in the market, except one, are imported. It is light sensitive and its photo-reaction products (nitrosophenylpyridine and nitrophenylpyridine derivatives) possess highly diminutized pharmacological activity. It is a yellow crystalline powder, with melting point range of 171 – 175oC (Al-Turk et al, 1989; Kennis et al, 2001; Martindale, 2002; USP/NF, 2002; BP, 2003). Apart from the relatively short half-life of the immediate release formulation, they have other short comings such as flushing, dizziness, palpitation and reflex tachycardia. These have necessitated the formulation of longer acting dosage forms and in some countries, the withdrawal of immediate release formulations from their markets (Brown et al, 1997; Minami et al, 2004; Emdex, 2006). 04-0766 047943 atherosclerosis (Hirata et al, 2000), amelioration of endothelium injury in patients with systemic sclerosis (Allanore et al, 2004) and enhancement of the activity of anticancer drugs in colon cancer treatment (Yang and Friedlander, 2001)
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