abacavir sulfate + lamivudine: clinical use

Prescribing considerations

• Document HLA-B*5701 status before initiation and provide an abacavir alert card.
• Review previous abacavir exposure and possible hypersensitivity symptoms.
• Assess renal and hepatic function, hepatitis B or C coinfection, resistance history and duplicate antiretrovirals.
• Assess cardiovascular risk and address modifiable factors; evidence concerning abacavir-associated cardiovascular events is inconsistent.
• The fixed-dose product is unsuitable when an individual component needs adjustment.

Contraindications and cautions

• Hypersensitivity to abacavir, lamivudine or an excipient.
• Positive HLA-B*5701 status.
• Previous suspected abacavir hypersensitivity, regardless of HLA-B*5701 status.

Monitoring

• HIV viral load and immune response.
• Hypersensitivity symptoms, particularly after initiation or interruption.
• Renal and hepatic function.
• Blood counts where renal impairment may increase lamivudine exposure.
• Weight, blood glucose and lipids.
• Liver function and HBV replication markers after discontinuation in people coinfected with hepatitis B.

Clinical pharmacology

Intracellular carbovir triphosphate and lamivudine triphosphate inhibit HIV reverse transcriptase and terminate viral DNA chains. Abacavir is mainly metabolised hepatically through alcohol dehydrogenase and glucuronidation; lamivudine is predominantly cleared unchanged by the kidneys.

Formulation and product differences

• The product is an oral fixed-dose film-coated tablet containing both active substances.
• Separate preparations permit component-specific adjustment or discontinuation when the fixed combination is unsuitable.
• The tablet contains sunset yellow FCF, which may cause allergic reactions, and is essentially sodium-free.

Tablet

Route: Oral

Strengths: 600 mg + 300 mg