The use of Phexxi® (lactic acid, citric acid, potassium bitartrate) vaginal gel prevented 99% of pregnancies per act of intercourse, according to findings from a post hoc analysis of the registrational phase 3 AMPOWER trial.

Phexxi is a nonhormonal, on-demand contraceptive designed to regulate vaginal pH in the range of 3.5 to 4.5, maintaining an acidic environment that is inhospitable to sperm. The vaginal gel is self-administered via a prefilled applicator immediately before or up to 1 hour before each act of vaginal intercourse. Phexxi is not effective for the prevention of pregnancy after intercourse.

The Food and Drug Administration (FDA) approved Phexxi for use as an on-demand method of contraception in 2020. The approval was based on data from the open-label, single-arm phase 3 AMPOWER trial ( Identifier: NCT03243305), which assessed the efficacy and safety of Phexxi in women aged 18 to 35 years who are at risk of pregnancy. Results showed a total of 101 on-treatment pregnancies occurred in 1183 participants contributing 4769 evaluable natural cycles. The 7-cycle typical use cumulative pregnancy rate was 13.7% (95% CI, 10.0-17.5) and the estimated Pearl Index was 27.5 (95% CI, 22.4-33.5).

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In the post hoc analysis, Phexxi was found to prevent 99% of pregnancies per act of intercourse based on 101 pregnancies (n=1182) over 24,289 acts of intercourse with typical use; the per-act-of-intercourse pregnancy risk was 0.415% (not statistically tested).

“Providing data showing how Phexxi performs on-demand to prevent pregnancy per act of intercourse helps women and their doctors better understand Phexxi and the value its innovation adds to the armamentarium of choice,” said Saundra Pelletier, Chief Executive Officer of Evofem.

Additional post hoc analyses of the AMPOWER trial showed a high level of sexual satisfaction among women who used Phexxi, as well as a lower incidence of urinary tract infections compared with the general study population (5.8% vs 11.0%, respectively).


Phexxi® prevented 99% of pregnancies per act of intercourse in a post hoc analysis of phase 3 AMPOWER clinical trial data. News release. Evofem Biosciences, Inc. Accessed June 16, 2022.

This article originally appeared on MPR