Fosamprenavir

Fosamprenavir calcium tablets are indicated in combination with other antiretroviral agents for the treatment of human immunodeficiency virus (HIV-1) infection. The following points should be considered when initiating therapy with fosamprenavir calcium tablets plus ritonavir in protease inhibitor-experienced patients: The protease inhibitor-experienced patient trial was not large enough to reach a definitive conclusion that fosamprenavir calcium tablets plus ritonavir and lopinavir plus ritonavir are clinically equivalent. Once-daily administration of fosamprenavir calcium tablets plus ritonavir is not recommended for adult protease inhibitor-experienced patients or any pediatric patients. Dosing of fosamprenavir calcium tablets plus ritonavir is not recommended for protease inhibitor-experienced pediatric patients younger than 6 months.

Fosamprenavir is an HIV-1 antiretroviral agent.

Therapy-Naive Adults: Fosamprenavir calcium tablets 1,400 mg twice daily, fosamprenavir calcium tablets 1,400 mg once daily plus ritonavir 200 mg once daily, fosamprenavir calcium tablets 1,400 mg once daily plus ritonavir 100 mg once daily, fosamprenavir calcium tablets 700 mg twice daily plus ritonavir 100 mg twice daily. Protease Inhibitor-Experienced Adults: Fosamprenavir calcium tablets 700 mg twice daily plus ritonavir 100 mg twice daily. Pregnant Patients: Fosamprenavir calcium tablets 700 mg twice daily plus ritonavir 100 mg twice daily should only be considered in women who are already on a stable twice-daily regimen of fosamprenavir calcium /ritonavir 700 mg/100 mg prior to pregnancy and who are virologically suppressed (HIV-1 RNA less than 50 copies per mL).

Fosamprenavir calcium is contraindicated in patients with previously demonstrated clinically significant hypersensitivity (e.g., Stevens-Johnson syndrome) to any of the components of this product or to amprenavir. Fosamprenavir calcium is contraindicated when coadministered with drugs that are highly dependent on cytochrome P450 (CYP)3A4 for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events. These drugs and other contraindicated drugs (which may lead to reduced efficacy of fosamprenavir calcium and possible resistance) are listed below.

The concomitant use of fosamprenavir calcium with ritonavir and certain other drugs may result in known or potentially significant drug interactions. Consult the full prescribing information prior to and during treatment for potential drug interactions. Fosamprenavir calcium should be discontinued for severe skin reactions, including Stevens-Johnson syndrome. Fosamprenavir calcium should be used with caution in patients with a known sulfonamide allergy. Use of higher-than-approved doses may lead to transaminase elevations. Patients with hepatitis B or C are at increased risk of transaminase elevations. Patients receiving fosamprenavir calcium may develop new onset or exacerbations of diabetes mellitus, hyperglycemia, immune reconstitution syndrome, increase of body fat, and elevated triglyceride and cholesterol concentrations.

Severe or life-threatening skin reactions have been reported with the use of fosamprenavir calcium. The most common moderate to severe adverse reactions in clinical trials of fosamprenavir calcium were diarrhea, rash, nausea, vomiting, and headache. Treatment discontinuation due to adverse events occurred in 6.4% of subjects receiving fosamprenavir calcium and in 5.9% of subjects receiving comparator treatments. The most common adverse reactions leading to discontinuation of fosamprenavir calcium (incidence less than or equal to 1% of subjects) included diarrhea, nausea, vomiting, AST increased, ALT increased, and rash. In adults the most common adverse reactions (incidence greater than or equal to 4%) are diarrhea, rash, nausea, vomiting, and headache. Vomiting and neutropenia were more frequent in pediatrics than in adults.

Coadministration of fosamprenavir calcium with drugs that induce CYP3A4 may decrease amprenavir (active metabolite) concentrations leading to potential loss of virologic activity. Coadministration with drugs that inhibit CYP3A4 may increase amprenavir concentrations. Coadministration of fosamprenavir calcium or fosamprenavir calcium and ritonavir may result in clinically significant interactions with drugs metabolized by CYP3A4. Coadministration of fosamprenavir calcium and ritonavir may result in clinically significant interactions with drugs metabolized by CYP2D6.

Store at 20° C to 25° C (68° F to 77° F). Protect from moisture.