The pharmacodynamic effects of combined administration of flibanserin and alcohol

Summary What is known and objective Flibanserin is a serotonin 5‐HT1A agonist and 5‐HT2A antagonist approved for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Because of the increased risk of hypotension‐ and syncope‐related adverse events (AEs) observed with coadministration of flibanserin and alcohol, alcohol use is contraindicated. To provide a more comprehensive understanding of the interaction between flibanserin and alcohol, the results of a dedicated phase 1 alcohol‐interaction study and a pooled analysis of phase 3 studies of premenopausal women with HSDD are presented. Methods In the phase 1 study, healthy participants (males [n=23] and females [n=2]) were randomly assigned to one of five sequence groups, which determined the order in which they were to receive flibanserin 100 mg or placebo, with or without ethanol 0.4 g/kg or 0.8 g/kg. Change from baseline in seated blood pressure, orthostatic vital signs, AEs and visual analogue scale sedation outcomes were examined. Blood samples were collected at baseline and for up to 4 hours after dosing to determine flibanserin area under the plasma concentration‐time curve from 0 to 4 hours (AUC0‐4). Pooled data from five phase 3 studies of patients receiving flibanserin 100 mg once daily (n=1543), or placebo (n=1905), were analysed. Results In the phase 1 study, the incidence of hypotension and syncope increased when flibanserin was coadministered with ethanol. Sedation increased 20% and 27% from baseline with flibanserin plus ethanol 0.4 g/kg and 0.8 g/kg, respectively, at 4 hours post‐dose. In the pooled analysis of phase 3 studies, 58.2% and 63.6% of participants receiving flibanserin or placebo, respectively, reported baseline alcohol use. In patients receiving flibanserin, fatigue and dizziness occurred more frequently in patients with vs. without alcohol use. What is new and conclusion Results from this study suggest that increased incidence of hypotension‐ and syncope‐related events may result from a pharmacodynamic interaction between flibanserin and alcohol, although the clinical significance of these interactions in real‐world populations remains unclear.