Pharmacokinetic and metabolic studies of vinpocetine on dogs. II. Metabolism.

Metabolic studies of vinpocetine were carried out by analysing the excreta of dogs treated orally or intravenously with the labelled compound. Our studies including various extraction procedures, TLC and MS structure identification revealed that vinpocetine underwent rapid and extensive metabolism in the animal organism. Unchanged parent drug was excreted via urine and feces only in a small or negligible portion. The prevailing metabolite in both urine and feces was apovincaminic acid. Two minor metabolites were also identified: hydroxy-vinpocetine and dihydroxy-apovincaminic acid-glycine amide. Beside the chemical structures and relative abundances of metabolites found in dogs, qualitative data referring to the metabolites occurring in the feces of orally treated humans, are also presented.