abacavir: clinical use

Prescribing considerations

• Document HLA-B*5701 status before initiation, regardless of racial origin.
• Prescribe only within combination antiretroviral therapy under clinicians experienced in HIV management.
• Educate patients and carers about hypersensitivity symptoms, interruption risks and the alert card.
• Consider alternatives in people with high cardiovascular risk and address modifiable cardiovascular factors.
• Review resistance history and the activity of the complete regimen.

Contraindications and cautions

• Known hypersensitivity to abacavir or a formulation excipient.
• Positive HLA-B*5701 status.
• Previous suspected abacavir hypersensitivity: never rechallenge with any abacavir-containing product.
• Use is not recommended in moderate or severe hepatic impairment unless specialist assessment considers it necessary; close monitoring is required in mild impairment.
• Avoid in end-stage renal disease because clinical experience is limited.

Monitoring

• HIV viral load, immunological response, adherence and resistance as clinically appropriate.
• New fever, rash, respiratory, gastrointestinal or constitutional symptoms—stop without delay if hypersensitivity is suspected.
• Liver function and clinical exposure concerns in hepatic impairment.
• Cardiovascular and metabolic risk factors, including blood pressure, lipids, glucose and weight.
• Methadone withdrawal symptoms during concurrent use.

Clinical pharmacology

Abacavir is an NRTI prodrug converted intracellularly to carbovir triphosphate, which inhibits HIV reverse transcriptase and terminates viral DNA-chain formation. It is primarily metabolised in the liver by alcohol dehydrogenase and glucuronidation, with little unchanged renal excretion and limited potential for major CYP-mediated interactions.

Formulation and product differences

• The selected product is a scored, film-coated oral tablet that should ideally be swallowed without crushing.
• An oral solution may be more suitable for children or people unable to take tablets.
• The solution reaches a slightly higher peak concentration than tablets, while overall exposure is comparable.

Tablet

Route: Oral

Strengths: 300 mg