Generic Name

Amprenavir

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Classification

FDA Approved Indications

• Treatment of HIV-1 infection in combination with other antiretroviral agents

Mechanism of Action

Amprenavir inhibits the HIV-1 protease enzyme, preventing cleavage of the Gag-Pol polyprotein into mature, functional proteins, thereby inhibiting viral maturation and replication.

Dosage and Administration

Adult: 600 mg twice daily with food

Pediatric: Not approved for pediatric use

Geriatric: No specific dose adjustment, but caution due to comorbidities and concomitant medications

Renal Impairment: Use with caution; no specific dosage adjustment required

Hepatic Impairment: Use with caution; no specific dosage adjustment, monitor hepatic function

Pharmacokinetics

Absorption: Rapidly absorbed; food increases absorption

Distribution: Widely distributed in tissues, crosses blood-brain barrier to a limited extent

Metabolism: Primarily via CYP3A4 enzymes

Excretion: Renal and fecal excretion of metabolites

Half Life: 5-6 hours

Contraindications

• Hypersensitivity to amprenavir or any component of the formulation

Precautions

• Use with caution in patients with sulfonamide allergy, hepatic impairment, or concomitant use with drugs that are CYP3A4 inhibitors or inducers. Monitor for liver toxicity and rash.

Adverse Reactions - Common

• Nausea (20-30%)
• Diarrhea (15-20%)
• Rash (10-20%)
• Headache (10-15%)

Adverse Reactions - Serious

• Severe rash including Stevens-Johnson syndrome (Rare)
• Hepatotoxicity (Rare)
• QT prolongation (Rare)

Drug-Drug Interactions

• Ritonavir (increases amprenavir levels)
• Midazolam, Triazolam (CYP3A4 substrates)

Drug-Food Interactions

• Grapefruit juice (may increase levels)

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication with food to enhance absorption.
• Report rash, fever, jaundice, or other signs of liver toxicity.
• Maintain adherence to minimize resistance.
• Avoid grapefruit juice and other CYP3A4 inhibitors or inducers without medical advice.

Special Considerations

Black Box Warnings:

• Severe rash including Stevens-Johnson syndrome, toxic epidermal necrolysis, and hypersensitivity reactions.

Genetic Factors: Testing for HLA-B*5701 recommended before initiating therapy to assess for potential hypersensitivity.

Lab Test Interference: May affect liver function tests and lipid panels.

Overdose Management

Signs/Symptoms: Nausea, vomiting, dizziness, hypotension, possible hepatic dysfunction.

Treatment: Supportive care; no specific antidote. Rapid absorption suggests vomiting or gastric lavage may be considered if ingestion is recent.

Storage and Handling

Storage: Store at room temperature (15°C to 30°C). Protect from moisture and light.

Stability: Stable under recommended storage conditions for the duration of the expiration date.