Lack of effect of rifalazil on ethinyl estradiol pharmacokinetics in healthy postmenopausal women

Drug interactions between rifamycin antibiotics and hormonal contraception: a systematic review

“…One study addressed COC PK with the experimental drug rifalazil (Table ). This single‐sequence crossover study administered a COC to 14 postmenopausal women for 14 days, and measured EE PK before and after a single oral dose of rifalazil (25 mg) on day 8 . EE AUC and Cmax remained within the prespecified GMR range of bioequivalence (CI of 80‐125%) following rifalazil.…”

“…We did not identify any studies using pregnancy rates as an outcome. Nine studies evaluated the effect of rifamycins on HC PK or ovulation, [13][14][15][16][17][18][19][20][21] one evaluated the effect of HC on rifamycin PK, 22 and one evaluated the effect of HC on TB treatment outcomes. 23…”

Pharmacokinetic Drug Interactions of Antimicrobial Drugs: A Systematic Review on Oxazolidinones, Rifamycines, Macrolides, Fluoroquinolones, and Beta-Lactams

“…Both rifalazil [112] and rifaximin [113] exhibited no effect on PK parameters of ethinyl estradiol after co-administration in healthy volunteers. A blinded randomized placebo-controlled, cross-over study of 19 healthy volunteers found the AUC of toremifene and of tamoxifen to be decreased by approximately 87% and the C max by 55% after co-administration with RIF [114].…”