NOCTURNAL PLASMA MELATONIN CONCENTRATIONS IN HEALTHY-VOLUNTEERS - EFFECT OF SINGLE DOSES OF D-FENFLURAMINE, PAROXETINE, AND IPSAPIRONE

The effect on nocturnal melatonin secretion of acute administration of the indirectly acting serotonin (5-HT) receptor agonists d-fenflurami ne (30 mg) and paroxetine (20 mg) and a partial 5-HT1A receptor agonis t ipsapirone (20 mg) was investigated in healthy male volunteers and c ompared to a placebo condition. Each subject (n=8) received each drug on one occasion over a 4 week study period, with drug administration s eparated by 1 week. A randomized, counter-balanced design was used. Dr ugs or placebo were administered at 2,000 hours in the light, and all blood samples were collected throughout the night in the dark at regul ar intervals until 0600 hours. Neither d-fenfluramine, paroxetine, or ipsapirone following acute dosage had a statistically significant effe ct on nocturnal melatonin synthesis. The lack of effect seen with d-fe nfluramine, paroxetine, and ipsapirone may be due to limitations impos ed by the dose requirements.