Excretion of valproic acid into semen of rabbits and man

Dipropylacetic acid (VPA, valproic acid) has been quantified in plasma and semen from rabbits and man using a new gas-liquid chromatographic assay. The drug assay is rapid, sensitive and free from interference by VPA metabolites. The beta phase half-life of VPA in rabbits after an i.v. dose (50 mg/kg) was 56 +/- 6 min. The concentration of VPA in rabbit plasma was 17 to 30 times the concentration in rabbit semen. In man, 500 mg doses of the free acid, p.o., resulted in VPA concentrations in plasma that were 11 to 17 times the concurrent levels in semen. VPA, in concentrations up to 10(-3) M, did not influence the motility of rabbit spermatozoa in vitro.