Maraviroc + Phenytoin = Precautionary

Effect on Concentration

Maraviroc
Decrease
Applies within class?
No
Phenytoin
No change
Applies within class?
No

Pharmacologic Effects

Maraviroc
Effect
N/A
Applies within class?
No
Phenytoin
Effect
N/A
Applies within class?
No

Interaction History

N/A

Last Updated 17-Jul-2018

Summary

Sources

Maraviroc versus CYP 3A4 inducers or inhibitors or substrates ^

Study Design

There are no formal interaction studies between these two agents.

Study Results

Ketoconazole 400mg daily, a CYP3A4 inhibitor, caused an increase in maraviroc’s Cmin by 275%, AUC by 400%, and Cmax by 238%. [141] The manufacturer has not supplied specifics on maraviroc levels, but they did state a lower dose of maraviroc was recommended when given with the following CYP3A inhibitors: itraconazole, clarithromycin, telithromycin, and nefazadone. Furthermore, any medication that is a CYP3A inhibitor could potentially increase maraviroc levels when co-administered. In a subsequent study, Abel et al found the geometric mean ratios for marviroc Cmax and AUC to be 338% and 501% respectively when co-administered with ketoconazole.

Study Conclusions

While the manufacturer did not supply specifics on maraviroc levels, they did state a lower dose of maraviroc was recommended due to the CYP3A inhibition nature of the following drugs: itraconazole, clarithromycin, nefazodone, etc. Furthermore, any medication that is a CYP3A inducers could potentially increase maraviroc levels when co-administered. Consider initiating maraviroc at 150 mg BID.

References

Abel S, et al. Effects of cyp3a4 inducers with and without cyp3a4 inhibitors on the pharmacokinetics of maraviroc in healthy volunteers. British Journal Of Clinical Pharmacology. 2008; : 38-46.