Fostemsavir + Rifampin = Prohibited

Effect on Concentration

Fostemsavir
Decrease
Applies within class?
No
Rifampin
Unknown
Applies within class?
No

Pharmacologic Effects

Fostemsavir
Effect
N/A
Applies within class?
No
Rifampin
Effect
N/A
Applies within class?
No

Interaction History

N/A

Last Updated 22-Nov-2022

Summary

Rifampin was shown to significantly reduce fostemsavir exposure and maximum concentration by 82% and 76%, respectively. Concomitant use of fostemsavir and rifampin is not recommended as this may lower fostemsavir efficacy.

Sources

Rifampin vs fostemsavir ^

Study Design

In an open-label, one sequence, one-way interaction study, the effect of rifampicin on the pharmacokinetics (PK) of single dose fostemsavir (formerly known as BMS-663068) was evaluated. 15 healthy subjects received a single dose of fostemsavir 1200 mg in the morning with a standard meal. Then, Participants received rifampicin 600 mg once daily in the evening for 7days (Days 6-12) together with a single dose of fostemsavir 1200 mg in the morning with a standard meal on Day 11. Samples for fostemsavir metabolite (BMS-626529) were taken pre-dose and up to 48 hours post-dose on Days 1 and 11. All participants were monitored for adverse events.

Study Results

Concomitant administration of fostemsavir and rifampin resulted in significant decrease of AUC and Cmax of BMS-626529; geometric mean ratios (GMRs; fostemsavir+rifampin / fostemsavir) [90% CI] of AUC and Cmax for fostemsavir were 0.181 [0.163, 0.200] and 0.241 [0.208, 0.279], respectively.

Study Conclusions

References

M Hruska, J Anderson, B Bedford, et al. The effect of rifampin on the pharmacokinetics of the hiv-1 attachment inhibitor prodrug bms-663068 in healthy subjects. 14th International Workshop On Clinical Pharmacology Of Hiv Therapy. Amsterdam, The Netherlands.. ; 2013.