BIOEQUIVALENCE OF PYRANTEL PAMOATE DOSAGE FORMS IN HEALTHY-HUMAN SUBJECTS

Drugs that are largely restricted to the gastro-intestinal tract (GIT) for their therapeutic efficacy and that are not substantially absorbe d into the body are usually inadequately studied in terms of systemic bioavailability. The possibility of systemic effects requires that bio availabilities be studied to ensure against enhanced toxicity resultin g from formulation differences. Pyrantel pamoate falls into this categ ory. High-performance liquid chromatography was employed in this study to determine plasma levels of pyrantel in nine healthy human subjects after administration of tablet and suspension dosage forms. Mean peak plasma concentrations of 37.56 +/- 9.37, 35.89 +/- 8.94, and 36.22 +/ - 10.10 ng mL(-1) were obtained following administration of 750 mg pyr antel pamoate in three different formulations. The mean t(max) values were 2.02 +/- 0.12, 2.05 +/- 0.356, and 2.05 +/- 0.339 h respectively for the above dosage forms; the respective AUC(0-9), values were 81.01 +/- 12.97, 94.59 +/- 17.18, and 101.47 +/- 19.59 h ng mL(-1). There w as no statistically significant difference between the bioavailabiliti es of the dosage forms tested. Large inter-subject variations were obs erved. One subject experienced abdominal discomfort and one experience d dizziness. It was not possible to clearly correlate individual varia tions in absorption with the observed adverse effect because the numbe r of incidents was low (two out of 27 treatments).