Adults

Adults: 500 mg once daily, or as directed by physician, usually in combination with other antiretroviral agents. Standard Abacavir dosage is 300 mg twice daily or 600 mg once daily.

Elderly

No specific dosage adjustment required, but use with caution due to potential age-related decline in renal, hepatic, or cardiac function.

Renal_impairment

No dosage adjustment required for mild to moderate renal impairment. Not recommended for patients with end-stage renal disease (ESRD) requiring dialysis.

Onset

Antiviral effects are typically observed within weeks to months of initiation, with sustained viral suppression with continued therapy.

Excretion

Excreted primarily in the urine (66% as metabolites) and feces (16% as metabolites).

Half life

Plasma half-life is approximately 1.5 hours; however, the intracellular half-life of its active metabolite, carbovir triphosphate, is significantly longer, supporting twice-daily dosing.

Absorption

Rapidly and extensively absorbed after oral administration. Bioavailability is approximately 83%.

Metabolism

Primarily metabolized in the liver by alcohol dehydrogenase and glucuronyl transferase. Less than 2% is excreted renally unchanged.

Alcohol

Increased abacavir concentrations. Co-administration with alcohol increases abacavir AUC by approximately 41%.

Methadone

Decreased methadone concentrations. Patients should be monitored for signs of methadone withdrawal.