Further characterisation of potential antidepressant action of flibanserin

Rationale: Flibanserin has shown antidepressant-like properties in some animal models. In order to better define the probability that flibanserin may act as an antidepressant, its effects were tested in additional tests. Objectives: To assess the activity of flibanserin in the forced swimming test in rats, in the distress call frequency in isolated chicks, in the tail suspension test in mice and in muricidal rats. Flibanserin was also tested in mice performing an operant schedule of a food reinforcement fixed at an interval of 2 min. Methods: Flibanserin was given intraperitoneally at a dose range between 0.5 and 32 mg/kg, 60 min before the muricidal test, 30 min before the tail suspension test, once (30 min) or three times (214, 5 and 1 h) before the forced swimming test, or just before testing (distress-induced calls in chicks). In the food reinforcement test in mice, flibanserin was given orally 60 min before testing. Results: Fibanserin showed an antidepressant-like effect in the distress-induced calls in chicks (5 mg/kg) and in the muricidal test (16 and 32 mg/kg), but not in the tail suspension test (from 7.5 to 30 mg/kg). Flibanserin (8 and 16 mg/kg) increased immobility in the forced swimming test, either when administered once or for three times. Flibanserin increased the operant responses in the food reinforcement test (40 mg/kg). Conclusions: Flibanserin showed antidepressant-like effects in two out of four tests, and increased animal drive in the operant paradigm. These findings, together with others already published, may suggest that flibanserin will exert antidepressant activity in humans.