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ANTIINFECTIVES FOR SYSTEMIC USE › ANTIVIRALS FOR SYSTEMIC USE › DIRECT ACTING ANTIVIRALS › Protease inhibitors
fosamprenavir
J05AE07
Forms & Strengths
- Oral tablets: 700 mg
- Oral suspension: 50 mg/mL
Adult Dosing
- Treatment-naive: 1400 mg once daily with ritonavir 100 mg once daily
- Treatment-experienced: 700 mg twice daily with ritonavir 100 mg twice daily
- PI-experienced: Not recommended for once-daily regimens in protease inhibitor-experienced patients
Pediatric Dosing
- Pediatric patients 4 weeks to < 2 years: Use not recommended due to insufficient data
- Pediatric patients 2 to 18 years (treatment-naive): 18 mg/kg with ritonavir 3 mg/kg twice daily (max 700 mg fosamprenavir + 100 mg ritonavir twice daily)
- Pediatric patients 2 to 18 years (PI-experienced): 12 mg/kg with ritonavir 3 mg/kg twice daily (max 700 mg fosamprenavir + 100 mg ritonavir twice daily)
Indications
- Treatment of HIV-1 infection in combination with other antiretroviral agents
- Management of HIV-1 in both treatment-naive and treatment-experienced adult and pediatric patients (>= 2 years)
Mechanism of Action
- Prodrug of amprenavir, an HIV-1 protease inhibitor
- Hydrolyzed to amprenavir in the gut epithelium during absorption
- Binds to the active site of HIV-1 protease, preventing cleavage of Gag-Pol polyproteins
- Results in the formation of immature, non-infectious viral particles
Contraindications
- Known hypersensitivity to fosamprenavir, amprenavir, or any component of the formulation
- Co-administration with drugs highly dependent on CYP3A for clearance and for which elevated plasma concentrations are associated with serious/life-threatening events (e.g., alfuzosin, amiodarone, cisapride, pimozide, rifampin, sildenafil for PAH, ergot derivatives, lovastatin, simvastatin)
- Co-administration with herbal products containing St. John's wort
Adverse Reactions
- Common: Headache, nausea, diarrhea, vomiting, fatigue, rash
- Metabolic: Hyperglycemia, new-onset or exacerbation of diabetes mellitus, hyperlipidemia (elevated triglycerides and cholesterol), fat redistribution
- Hepatic: Elevations in serum transaminases (ALT, AST), hepatotoxicity
- Severe: Severe skin reactions including Stevens-Johnson syndrome, hypersensitivity reactions, bleeding episodes in patients with hemophilia
Drug Interactions
- Ritonavir: Pharmacokinetic enhancer, increases amprenavir exposure; dosage adjustments required
- CYP3A4 inducers (e.g., rifampin, carbamazepine, phenobarbital): Significantly decrease amprenavir plasma concentrations; avoid co-administration
- CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): May increase amprenavir concentrations
- HMG-CoA reductase inhibitors: Increased risk of myopathy/rhabdomyolysis with lovastatin and simvastatin; atorvastatin and rosuvastatin require cautious dose titration
- PDE5 inhibitors: May increase concentrations of sildenafil, tadalafil, or vardenafil; dose reductions of PDE5 inhibitors required
- Hormonal contraceptives: May decrease efficacy of systemic hormonal contraceptives; alternative reliable barrier or non-hormonal methods recommended
Curated Content: Needs Vetting Before Put to Clinical Use