RESUMEN
Metronidazole is an antiprotozoal drug which is also effective against anaerobic bacteria. It exhibits pronounced in-vitro and in-vivo activity against Trichomonas vaginalis and E. histolytica. Many different brands and dosage forms of Metronidazole are available in the gulf countries that place physicians and pharmacists in a dilemma of drug substitution in case of non availability of a particular brand. The present study was aimed to evaluate the pharmaceutical equivalence of four brands of 250 mg Metronidazole tablets marketed in Middle East countries. Four brands of Metronidazole tablets were purchased locally from the retail pharmacy outlets in Muscat, Oman and their solubility, partition coefficient [log P] and pharmaceutical quality were assessed by using in-vitro tests as per the United States Pharmacopoeia [USP] and unofficial standards as recommended by the manufacturers. Selected brands of Metronidazole were found to be highly soluble, highly permeable and also passed all the official and unofficial in- vitro quality control tests prescribed for the tablets except hardness test. All brands of Metronidazole tablets released more than 70% of their drug content within 45 minutes. Thus, based on the above results, it can be concluded that tested brands of Metronidazole tablets being eligible for biowaiver, are pharmaceutically equivalent and therefore can be considered for drug substitution for each other