THE EFFECTS OF D-FENFLURAMINE AND L-FENFLURAMINE (AND THEIR INTERACTIONS WITH D-AMPHETAMINE) ON PSYCHOMOTOR FUNCTION AND MOOD

This study reports the results on psychomotor functioning of D- and L- fenfluramine alone, and in combination with D-amphetamine, in a placeb o-controlled trial on 12 normal male volunteers, in order to investiga te their CNS activity in humans. The major findings were that D-amphet amine increased alertness, L-fenfluramine increased unhappiness whilst D-fenfluramine decreased hunger and increased the critical flicker fu sion threshold. D-Amphetamine in combination with D-fenfluramine incre ased the critical flicker fusion threshold and in combination with L-f enfluramine the alerting action was diminished. The differing actions of the fenfluramine isomers and their interactions with D-amphetamine suggest that D-fenfluramine is predominantly serotonergic in its activ ity, whereas D-fenfluramine may be causing dopamine blockade, reducing certain actions of amphetamine possibly mediated by dopamine receptor s. The significance of these results in relationship to the psychophar macology of serotonin, dopamine, and noradrenaline is discussed.