A Review of the Pharmacokinetics of Abacavir

Abacavir is a carbocyclic 2′-deoxyguanosine nucleoside reverse transcriptase inhibitor that is used as either a 600-mg once-daily or 300-mg twice-daily regimen exclusively in the treatment of HIV infection. Abacavir is rapidly absorbed after oral administration, with peak concentrations occurring 0.63–1 hour after dosing. The absolute bioavailability of abacavir is approximately 83%. Abacavir pharmacokinetics are linear and doseproportional over the range of 300–1200 mg/day. To date, one study has assessed the steady-state pharmaco-kinetics of abacavir following a 600-mg once-daily regimen, and reported a geometric mean steady-state abacavir peak concentration of 3.85 µg/mL. Although this concentration is higher than the steady-state abacavir peak concentration reported following a 300-mg twice-daily regimen (0.88–3.19 µg/mL, depending on the study), the geometric mean steady-state abacavir exposure over 24 hours was similar following these regimens. Coadministration with food has no significant effect on abacavir exposure; therefore, abacavir may be administered with or without food.