ABSTRACT
Because studies showed similar viral suppression with lower raltegravir doses and because Asians usually have high antiretroviral concentrations, we explored low-dose raltegravir therapy in Thais. Nineteen adults on raltegravir at 400 mg twice daily (BID) with HIV RNA loads of <50 copies/ml were randomized to receive 400 mg once daily (QD) or 800 mg QD for 2 weeks, followed by the other dosing for 2 weeks. Intensive pharmacokinetic analyses were performed, and HIV RNA was monitored. Two patients were excluded from the 400-mg QD analysis due to inevaluable pharmacokinetic data. The mean patient weight was 58 kg. Mean pharmacokinetic values were as follows: for raltegravir given at 400 mg BID, the area under the concentration-time curve from 0 to 12 h (AUC0â12) was 15.6 mg/liter-h and the minimum plasma drug concentration (C(trough)) was 0.22 mg/liter; for raltegravir given at 800 mg QD, the AUC0â24 was 33.6 mg/liter-h and the C(trough) was 0.06 mg/liter; and for raltegravir given at 400 mg QD, the AUC0â24 was 18.6 mg/liter-h and the C(trough) was 0.08 mg/liter. The HIV RNA load was <50 copies/ml at each dose level. Compared to the adjusted AUC0â24 for Westerners on raltegravir at 400 mg BID, Thais on the same dose had double the AUC0â24 and those on raltegravir at 400 mg QD had a similar AUC0â24. More patients had a C(trough) of <0.021 mg/liter on raltegravir at 400 mg QD (9/17 patients) than on raltegravir at 800 mg QD (1/19 patients) or 400 mg BID (0/19 patients). Seventeen patients used raltegravir at 400 mg QD for a median of 35 weeks; two had confirmed HIV RNA loads between 50 and 200 copies/ml, and both had low C(trough) values. Low-dose raltegravir could be a cost-saving option for maintenance therapy in Asians or persons with low body weight. However, raltegravir at 400 mg QD was associated with a low C(trough) and with a risk for HIV viremia. Raltegravir at 200 or 300 mg BID should be studied, but new raltegravir formulations will be needed.
