A COMPARISON OF THE IN VIVO INHIBITION OF BRAIN AND LIVER MONOAMINE OXIDASE AS PRODUCED BY BETA-PHENYLISOPROPYLHYDRAZINE (PIH) AND IPRONIAZID

¹ Department of Pharmacolog, School of Medicine, University of Oklahoma, Oklahoma City, Oklahoma
² Department of Pharmacolog, University of Washington School of Medicine, Seattle, Washington

A study has been carried out to determine the comparative in vivo effectiveness of two monoamine oxidase inhibitors, beta-phenylisopropylhydrazine (JB-5l6, PIH) and 1-isonicotinyl-2-isopropylhydrazine (iproniazid), on monoamine oxidase activity in rat brain and liver. The results of this investigation indicate that: 1) The onset of monoamine oxidase inhibition by PIH is rapid, while iproniazid displays a lag period before maximal inhibition is produced. 2) PIH and iproniazid are approximately equipotent in reducing or abolishing the monoamine oxidase activity in rat liver in vivo. In brain, however, PIH exerts a much greater effect than does iprornazid. 3) A dose-response curve of these two drugs indicate that in vivo PIH produces inhibition of brain monoamine oxidase at lower doses than it does with the liver enzyme, while the converse relationship is seen with iproniazid.