abacavir sulfate: clinical use

Prescribing considerations

• Use only within specialist-managed combination antiretroviral therapy.
• Document HLA-B*5701 status and previous exposure or suspected hypersensitivity before initiation.
• Review resistance history, treatment interruptions, hepatic disease and concurrent medicines.
• Assess modifiable cardiovascular risk factors; consider alternatives in patients at high cardiovascular risk.
• The oral solution's excipients require additional assessment in young children, pregnancy, lactation and renal or hepatic impairment.

Contraindications and cautions

• Positive HLA-B*5701 status.
• Previous suspected abacavir hypersensitivity, regardless of HLA-B*5701 result.
• Hypersensitivity to abacavir or a formulation excipient.
• Hereditary fructose intolerance for the selected sorbitol-containing oral solution.

Monitoring

• Watch closely for multisystem hypersensitivity, particularly after initiation or interruption.
• Monitor HIV response and adherence as part of the complete regimen.
• Monitor liver function where hepatic disease or impairment is present.
• Review weight, blood lipids and glucose during antiretroviral treatment.
• With methadone, monitor for withdrawal symptoms.

Clinical pharmacology

Abacavir is activated intracellularly to carbovir triphosphate, which inhibits HIV-1 and HIV-2 reverse transcriptase and causes viral DNA chain termination. It is rapidly absorbed, has low-to-moderate protein binding and is cleared mainly through hepatic metabolism, with metabolites excreted primarily in urine.

Formulation and product differences

• The selected film-coated tablet is scored, can be divided into equal parts and may be crushed for immediate administration with a small amount of food or liquid.
• The selected oral solution is measured with the supplied oral syringe and contains sorbitol, propylene glycol and parabens. It should not be stored above 25°C.
• Sorbitol may have a laxative effect and makes the oral solution unsuitable for people with hereditary fructose intolerance.

Oral solution

Route: Oral

Strengths: 20 mg/mL

Tablet

Route: Oral

Strengths: 300 mg