Fosamprenavir Dosage

Medically reviewed by Drugs.com. Last updated on Apr 4, 2025.

Usual Adult Dose for HIV Infection

Therapy-Naive Patients:

• Without ritonavir: 1400 mg orally twice a day
• With ritonavir:
• Once-daily regimen: Fosamprenavir 1400 mg plus ritonavir 100 or 200 mg orally once a day
• Twice-daily regimen: Fosamprenavir 700 mg plus ritonavir 100 mg orally twice a day

Protease Inhibitor-Experienced Patients: Fosamprenavir 700 mg plus ritonavir 100 mg orally twice a day

Comments:

• According to some experts, the use of unboosted fosamprenavir or the once-daily regimen is not recommended during pregnancy.

Use: In combination with other antiretroviral agents, for the treatment of HIV-1 infection

Usual Adult Dose for Nonoccupational Exposure

US CDC Recommendations: 1400 mg orally twice a day
Duration of therapy: 28 days

Comments:

• Only with expert consultation, as part of an alternative regimen for use as nonoccupational postexposure prophylaxis of HIV infection
• Prophylaxis should be started as soon as possible, within 72 hours of exposure.
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Occupational Exposure

US Public Health Service Working Group Recommendations:

• Preferred dosing (with ritonavir): Fosamprenavir 1400 mg plus ritonavir 100 mg orally once a day
• Alternative dosing (without ritonavir): 1400 mg orally twice a day

Duration of therapy: 28 days, if tolerated

Comments:

• Only with expert consultation, as part of an alternative regimen for use as HIV postexposure prophylaxis
• Prophylaxis should be started as soon as possible, preferably within hours after exposure.
• The optimal duration of prophylaxis is unknown and may differ based on institution protocol.
• Current guidelines should be consulted for additional information.

Usual Pediatric Dose for HIV Infection

WITHOUT RITONAVIR:
Protease Inhibitor-Naive Patients (Aged 2 Years or Older):
Oral suspension: 30 mg/kg orally twice a day

• Maximum dose: 1400 mg/dose

Tablets:

• Weight at least 47 kg: 1400 mg orally twice a day

WITH RITONAVIR:
Protease Inhibitor-Naive Patients (Aged 4 Weeks or Older) and Protease Inhibitor-Experienced Patients (Aged 6 Months or Older):
Oral suspension:

• Weight less than 11 kg: Fosamprenavir 45 mg/kg plus ritonavir 7 mg/kg orally twice a day
• Weight 11 to less than 15 kg: Fosamprenavir 30 mg/kg plus ritonavir 3 mg/kg orally twice a day
• Weight 15 to less than 20 kg: Fosamprenavir 23 mg/kg plus ritonavir 3 mg/kg orally twice a day
• Weight at least 20 kg: Fosamprenavir 18 mg/kg plus ritonavir 3 mg/kg orally twice a day
• Maximum dose: Fosamprenavir 700 mg/dose; ritonavir 100 mg/dose

Tablets:

• Weight at least 39 kg: Fosamprenavir 700 mg plus ritonavir 100 mg orally twice a day

Comments:

• This drug should only be administered to infants at least 38 weeks gestation at birth who have attained a postnatal age of 28 days.
• The Panel on Antiretroviral Therapy and Medical Management of Children Living with HIV does not recommend using boosted fosamprenavir (with ritonavir) in infants younger than 6 months or using unboosted fosamprenavir (without ritonavir) in antiretroviral-naive children (any age); current guidelines should be consulted for additional information.
• Ritonavir capsules may be used for patients weighing at least 33 kg.

Use: In combination with other antiretroviral agents, for the treatment of HIV-1 infection

Renal Dose Adjustments

No adjustment recommended.

Liver Dose Adjustments

Adult Patients:
Mild liver dysfunction (Child-Pugh score ranging from 5 to 6):

• Therapy-naive:
• Without ritonavir: 700 mg orally twice a day
• With ritonavir: Fosamprenavir 700 mg orally twice a day plus ritonavir 100 mg once a day
• Protease inhibitor-experienced: Fosamprenavir 700 mg orally twice a day plus ritonavir 100 mg once a day

Moderate liver dysfunction (Child-Pugh score ranging from 7 to 9):

• Therapy-naive:
• Without ritonavir: 700 mg orally twice a day
• With ritonavir: Fosamprenavir 450 mg orally twice a day plus ritonavir 100 mg once a day
• Protease inhibitor-experienced: Fosamprenavir 450 mg orally twice a day plus ritonavir 100 mg once a day

Severe liver dysfunction (Child-Pugh score ranging from 10 to 15):

• Therapy-naive:
• Without ritonavir: 350 mg orally twice a day
• With ritonavir: Fosamprenavir 300 mg orally twice a day plus ritonavir 100 mg once a day
• Protease inhibitor-experienced: Fosamprenavir 300 mg orally twice a day plus ritonavir 100 mg once a day

Pediatric Patients: Data not available

Comments:

• This drug should be used with caution in adults with liver dysfunction.

Dose Adjustments

Adults:
Coadministration with efavirenz:

• Once-daily regimen: Fosamprenavir 1400 mg plus ritonavir 300 mg orally once a day
• Twice-daily regimen: Fosamprenavir 700 mg plus ritonavir 100 mg orally twice a day

Precautions

CONTRAINDICATIONS:

• Previously demonstrated clinically significant hypersensitivity (e.g., Stevens-Johnson syndrome) to the active component or any of the ingredients
• Coadministration with drugs highly dependent on CYP450 3A4 for clearance and for which elevated plasma levels are associated with severe and/or life-threatening events
• With or without ritonavir: Coadministration with alfuzosin, rifampin, dihydroergotamine, ergonovine, ergotamine, methylergonovine, cisapride, St. John's Wort, pimozide, midazolam, triazolam, lovastatin, simvastatin, delavirdine, sildenafil (for treatment of pulmonary arterial hypertension)
• With ritonavir: Coadministration with lurasidone, flecainide, propafenone

Safety and efficacy have not been established in patients younger than 4 weeks; this drug (with or without ritonavir) is not recommended for use in protease inhibitor-experienced patients younger than 6 months.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Comments:

• Amprenavir is highly protein-bound; significant removal via hemodialysis or peritoneal dialysis is not likely.

Other Comments

Administration advice:

• Use in combination with other antiretroviral agents.
• Oral suspension: Administer without food in adult patients and with food in pediatric patients; re-dose if emesis occurs within 30 minutes after dosing.
• Oral suspension: Shake vigorously before each administration.
• Tablets: May administer with or without food
• Do not use higher than approved dose combinations of this drug plus ritonavir (increased risk of transaminase elevations).
• Consult the manufacturer product information regarding missed doses.

Storage requirements:

• Oral suspension: Store in refrigerator or at room temperature (5C to 30C [41F to 86F]); do not freeze.
• Tablets: Store at controlled room temperature (25C [77F]); excursions permitted to 15C to 30C (59F to 86F); keep bottle tightly closed.

General:

• Once-daily administration of this drug plus ritonavir is not recommended for adult protease inhibitor-experienced patients.
• Once-daily dosing of this drug (with or without ritonavir) is not recommended for any pediatric patients.
• Twice-daily dosing of this drug without ritonavir is not recommended in pediatric patients younger than 2 years.
• The protease inhibitor-experienced patient trial was not large enough to definitively conclude that this drug plus ritonavir and lopinavir-ritonavir are clinically equivalent; this should be considered when starting this drug plus ritonavir in protease inhibitor-experienced patients.
• The manufacturer product information for ritonavir should be consulted (if applicable).

Monitoring:

• Hepatic: Appropriate laboratory testing in patients with underlying liver disease (before starting and during therapy)
• Metabolic: Triglyceride and cholesterol testing (before starting and during therapy)

Patient advice:

• Read the US FDA-approved patient labeling (Patient Information).
• If taking a combined hormonal contraceptive: Use an effective alternative contraceptive method or an additional barrier method during therapy.
• Stop this drug at once if severe/life-threatening skin reactions or moderate rashes with systemic symptoms develop.
• Do not use higher than recommended doses.
• Notify healthcare provider at once of any signs/symptoms of infection.
• If using the oral suspension: Shake the bottle vigorously before each use; refrigeration may improve the taste.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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