Biovailability of four pharmaceutical formulations of metronidazole tested on normal healthy volunteers

ABSTRACT

1. Single doses of four metronidazole formulations (the unmarketed Trichomol, 200 mg, 200 mg, 400 mg, 500 mg, and the commercially available Flagyl, 400 mg) were administered to 14 healthy adult male volunteers in order to determine their pharmacokinetic profiles. 2. Plasma metronidazole concentrations were measured by high pressure liquid chromatography. The results were plotted against time and the curves obtained were used to calculate pharmacokinetic parameters ( area under the curves, maximun achieved concentration and time at which it occurred, elimination constant, and half-life). 3. Trichomol formulations of 200 mg and 500 mg significantly differed from the 400 mg formulation with respect to area under the curve and maximum concentration. Trichomol 400 mg and Flagyl 400 mg showed no significant differences in maximum concentration or area under the curve. No differences were observed in half-life or time of appearance of maximum concentration among formulations. 4. Good correlations occurred between maximum concentration, area under the curve and amount of metronidazole ingested, indicating a linear pharmacokinetic profile. 5. We conclude that Trichomol 400 mg proved to be bioequivalent to the commercially available reference Flagyl 400 mg according to U.S. Food and Drug Adminsitration requirements