Ketanserin antagonises the anorectic effect of DL-fenfluramine in the rat.

To determine the role played by 5-HT2 receptors in the anorectic action of DL-fenfluramine, the ability of the selective 5-HT2 receptor antagonist ketanserin to block the reduction in food intake produced by this drug was investigated in non-deprived rats. Ketanserin (1 and 2.5 mg/kg i.p.) produced a dose-dependent antagonism of the anorectic effect of DL-fenfluramine (3 mg/kg i.p.). Prazosin (1 mg/kg i.p.) did not antagonise this effect. It is concluded that the anorectic actions of DL-fenfluramine are mediated via 5-HT2 receptors.