Drug Interaction Report

Using ethinyl estradiol together with fosamprenavir may decrease the effects of fosamprenavir. Alternative or nonhormonal methods of birth control should be considered if you are treated with fosamprenavir. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Fosamprenavir suspension should be administered on an empty stomach in adults, but with food in pediatric patients to help the taste and compliance. If vomiting occurs within 30 minutes after dosing the suspension, the dose should be repeated. Fosamprenavir tablets may be taken with or without food. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

MONITOR: Coadministration of ethinyl estradiol may increase the plasma concentrations of drugs that are primarily metabolized by CYP450 1A2. In a study of 30 healthy volunteers administered the CYP450 1A2 substrate tizanidine, the systemic exposure (AUC) of tizanidine was 3.9 times greater in women using an oral contraceptive containing ethinyl estradiol.

MANAGEMENT: Patients should be monitored for increased adverse effects of the CYP450 1A2 substrate during concomitant use with ethinyl estradiol. Product labeling for the specific CYP450 1A2 substrate should be consulted for additional recommendations.

Information for this minor interaction is available on the professional version.

Information for this minor interaction is available on the professional version.