Pharmacokinetics of valpromide in dogs after various modes of administration

Valpromide‐Depropylacetamide was administered to five dogs via five modes: Three oral formulations (solution, capsule, and enteric‐coated tablet), intravenous and intra‐muscular injections. No significant change in the terminal half‐life of valpromide could be observed after the various modes of administration in each dog. Valpromide was more rapidly absorbed after the administration of an oral solution than after i.m. injection. Similar data also were obtained for its metabolite—valproic acid. It was shown that valpromide in the dogs was partly biotransformed to valproic acid. The average fraction of valpromide that was transformed to valproic acid (fm) ranged from 30–35 per cent after all the oral and parenteral administrations, except for the enteric‐coated tablet, which showed a very low bioavailability of valpromide.