Effects of Timing of Flibanserin Administration Relative to Alcohol Intake in Healthy Premenopausal Women: A Randomized, Double-Blind, Crossover Study

J Sex Med. 2019 Nov;16(11):1779-1786. doi: 10.1016/j.jsxm.2019.08.006. Epub 2019 Sep 12.


Introduction: Flibanserin is approved in the United States and Canada for the treatment of acquired, generalized, hypoactive sexual desire disorder in premenopausal women. Sedation-related side effects are among the most prevalent adverse events. Although infrequent, hypotension and syncope remain safety concerns because of possible interaction of flibanserin with alcohol.

Aim: To evaluate the impact of the timing of alcohol consumption on flibanserin safety and tolerability.

Methods: In this single-center, randomized, double-blind, placebo-controlled, 4-treatment crossover study, 64 healthy premenopausal women (mean age 32.5 ± 8.7 years; range 20‒52 years) received once-daily flibanserin 100 mg or placebo during each of two 10-day treatment periods. Study medication was administered on days 1-3 to achieve steady state. On days 4, 6, 8, and 10, after a standard breakfast, participants consumed 0.4 g/kg ethanol (approximately equivalent to two 5-oz glasses of wine) administered with orange juice 2, 4, or 6 hours before taking study medication or orange juice alone (no ethanol) 2 hours before taking study medication.

Outcomes: The primary endpoint was percentage of participants experiencing syncope or orthostatic hypotension-associated adverse events requiring medical intervention. Secondary endpoints included the incidence of hypotension, the incidence of orthostatic hypotension, and rates of adverse events of special interest (syncope, orthostatic hypotension, dizziness, and somnolence).

Results: 1 participant experienced a primary endpoint event (syncope) during treatment with placebo taken 4 hours after ethanol consumption. Within each ethanol dose-timing treatment, there were no statistically significant differences for flibanserin compared with placebo. Rates of hypotension were 53.3-66.7% after flibanserin dosing and 57.4-63.3% after placebo dosing. Rates for orthostatic hypotension were 0.0-5.0% after flibanserin dosing and 1.7-6.6% after placebo dosing.

Clinical implications: Ethanol interaction with flibanserin was not observed in this study.

Strengths & limitations: This study provides information regarding the use of flibanserin after the consumption of moderate amounts of ethanol (0.4 g/kg). However, daytime administration of flibanserin is not consistent with the drug's indicated bedtime dosing.

Conclusion: Flibanserin, at steady state taken 2, 4, or 6 hours after 0.4 g/kg of ethanol intake did not increase the incidence of hypotension, orthostatic hypotension, or syncope compared with either flibanserin alone or ethanol alone. Simon JA, Clayton AH, Kingsberg SA, et al. Effects of Timing of Flibanserin Administration Relative to Alcohol Intake in Healthy Premenopausal Women: A Randomized, Double-Blind, Crossover Study. J Sex Med 2019;16:1779-1786.

Keywords: Ethanol; Flibanserin; Hypoactive Sexual Desire Disorder; Hypotension; Orthostatic Hypotension; Syncope.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alcohol Drinking / epidemiology*
  • Benzimidazoles / administration & dosage*
  • Benzimidazoles / adverse effects
  • Cross-Over Studies
  • Double-Blind Method
  • Female
  • Humans
  • Middle Aged
  • Premenopause*
  • Young Adult


  • Benzimidazoles
  • flibanserin