CHRONOPHARMACOLOGICAL STUDY OF MOCLOBEMIDE EFFECT ON THE RAT PINEAL MELATONIN BIOSYNTHESIS

The chronopharmacological hypothesis of the mechanism of the antidepre ssant effect of MAO-A inhibitors predicts that clinical efficacy depen ds upon the time of the day at which the drugs are administered. In th e present study moclobemide (10 mg/kg, s.c.) injected at the end of th e light phase advanced the onset of the nighttime increase of the rat pineal melatonin biosynthesis while the same dose of drug injected at the end of the dark phase delayed the daytime decrease of melatonin bi osynthesis. The results obtained suggest that the timing of MAO-A inhi bitor administration should be considered in clinical practice.