Bioavailability study of a concentrated suspension of phenytoin in healthy volunteers

Abstract

Abstract The bioequivalence of a new concentrated suspension of phenytoin was compared with the standard reference solution recommended by the United Kingdom Committee on Review of Medicines in a group of 18 healthy male volunteers. Doses of 5ml (94.6mg) of the new formulation and 50ml (92mg) of the reference solution were administered in a randomised crossover design and blood samples were withdrawn over the next 72 hours. Serum concentrations were analysed by high performance liquid chromatography. There were no significant differences in the areas under the plasma concentration-time curves of the two formulations although the time to peak was shorter and peak concentrations were higher with the reference solution. As the total amount of phenytoin absorbed from each preparation was not significantly different, both formulations have the same relative bioavailability. This new concentrated phenytoin suspension may have clinical advantages over tablets, capsules and the commercially available low strength suspension, in patients who have difficulty in swallowing but require normal adult doses of phenytoin