[Inhibition of brain monoamine oxidase in the rat by multiple pyrazidol administration]

Pyrazidol, which is chemically 2,3, 3a, 4, 5, 6-hexahydro-8-methyl-1H-pyrazino[3,2,1-j,k] carbazole hydrochloride (international name pirlindole) administered repeatedly (21 days) to rats at a dose of 25 mg/kg per os maintained the selectivity of its inhibitory effect toward type A MAO. When administered repeatedly the inhibitory effect of pyrazidol was 1.5-2-fold higher than after a single administration. The effect of pyrazidol on rat brain MAO was reversible whatever the route of administration. The enzymatic activity returned to normal within 24 h after the last administration. The data obtained suggest that the capacity of selective inhibiting the deamination of the neurotransmitters such as serotonin and noradrenaline in human brain is of paramount importance for therapeutic effect of pyrazidol.