Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection

The information in the brief version is excerpted directly from the full-text guidelines. The brief version is a compilation of the tables and boxed recommendations.

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Protease Inhibitors (PIs)

Fosamprenavir

Last Updated: May 22, 2018; Last Reviewed: May 22, 2018

Fosamprenavir (FPV, Lexiva)
Fosamprenavir (FPV, Lexiva)
For additional information see Drugs@FDA: https://www.accessdata.fda.gov/scripts/cder/daf/
Formulations
Tablets: 700 mg
Oral Suspension
: 50 mg/mL
Dosing Recommendations Selected Adverse Events
Pediatric Dose (Aged >6 Months to 18 Years):
  • Unboosted fosamprenavir (without ritonavir) is Food and Drug Administration (FDA)-approved for antiretroviral (ARV)-naive children aged 2 to 5 years, but not recommended by the Panel on Antiretroviral Therapy and Medical Management of Children Living with HIV (the Panel) because of low exposures (see text below).
  • Boosted fosamprenavir (with ritonavir) is FDA-approved for ARV-naive infants ≥4 weeks and for treatment-experienced infants ≥6 months; however, the Panel does not recommend use in infants aged <6 months because of similarly low exposures (see text below). If used in infants as young as 4 weeks, it should only be administered to infants born at 38 weeks’ gestation or greater.
Note: Once-daily dosing is not recommended for any pediatric patient.

Pediatric Dose (Aged ≥6 Months to 18 Years):
Twice-Daily Dose Regimens by Weight for Pediatric Patients ≥6 Months Using Fosamprenavir Oral Suspension with Ritonavir
Weight Dose (Both Drugs Twice Dailya with Food)
<11 kg Fosamprenavir 45 mg/kg/dose plus ritonavir 7 mg/kg/dose
11 kg to <15 kg Fosamprenavir 30 mg/kg/dose plus ritonavir 3 mg/kg/dose
15 kg to <20 kg Fosamprenavir 23 mg/kg/dose plus ritonavir 3 mg/kg/dose
≥20 kg Fosamprenavir 18 mg/kg/dose plus ritonavir 3 mg/kg/dose
a Not to exceed the adult dose of fosamprenavir 700 mg plus ritonavir 100 mg twice daily.

Note: When administered with ritonavir, the adult regimen of 700 mg fosamprenavir tablets plus 100 mg ritonavir, both given twice daily, can be used in patients weighing ≥39 kg. Ritonavir tablets can be used in patients weighing ≥33 kg.

Adolescent and Adult Dose:
  • Dosing regimen depends on whether the patient is ARV-naive or ARV-experienced.
ARV-Naive Patients:
  • Fosamprenavir 700 mg plus ritonavir 100 mg, both twice daily
  • Fosamprenavir 1400 mg plus ritonavir 100–200 mg, both once daily
Protease-Inhibitor-Experienced Patients:
  • Fosamprenavir 700 mg plus ritonavir 100 mg, both twice daily.
Note: Once-daily administration of fosamprenavir plus ritonavir is not recommended.
  • Diarrhea, nausea, vomiting
  • Skin rash (fosamprenavir has a sulfonamide moiety. Stevens-Johnson syndrome and erythema multiforme have been reported.)
  • Headache
  • Hyperlipidemia, hyperglycemia
  • Nephrolithiasis
  • Transaminase elevation
  • Fat maldistribution
  • Possible increased bleeding episodes in patients with hemophilia
Special Instructions
  • Fosamprenavir tablets with ritonavir should be taken with food. Children should take the suspension with food.
  • Patients taking antacids should take fosamprenavir at least 1 hour before or after antacid use.
  • Fosamprenavir contains a sulfonamide moiety. The potential for cross sensitivity between fosamprenavir and other drugs in the sulfonamide class is unknown. Fosamprenavir should be used with caution in patients with sulfonamide allergy.
  • Shake oral suspension well before use. Refrigeration is not required.
Metabolism/Elimination
  • The prodrug fosamprenavir is rapidly and almost completely hydrolyzed to amprenavir by cellular phosphatases in the gut as it is absorbed.
  • Amprenavir is a cytochrome P (CYP) 450 3A4 inhibitor, inducer, and substrate.
Fosamprenavir Dosing in Patients with Hepatic Impairment:
  • Specific dose adjustments are recommended for adults with mild, moderate, and severe hepatic impairment. However, there are no data to support dosing recommendations for pediatric patients with hepatic impairment. Please refer to the package insert.
Fosamprenavir Dosing in Patients with Renal Impairment:
  • No dose adjustment is required in patients with renal impairment.

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