Lack of interaction between flibanserin and antidepressants in inducing serotonergic syndrome in rats

This study was aimed at evaluating the ability of flibanserin, a 5-HT1A receptor full agonist with antidepressant potential, to induce the 5-HT syndrome (flat body posture, hindlimb abduction and forepaw treading) in rats previously administered with clinically active antidepressants imipramine, fluoxetine or paroxetine. The 5-HT syndrome was observed for 50 min after intraperitoneal administration of flibanserin (0, 8 or 64 mg/kg) given 10 min after antidepressants (0 or 15 mg/kg). Flibanserin induced flat body posture and very slight hindlimb abduction only at 64 mg/kg. No dose of flibanserin elicited forepaw treading. Similar but milder symptoms were induced by antidepressants. No interaction between flibanserin and antidepressants was observed. A dose of 10 mg/kg flibanserin did not change the flat body posture induced by 8 mg/kg (±)-8-OH-DPAT but antagonized (±)-8-OH-DPAT-induced forepaw treading.