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Low-Dose Lopinavir/RTV Tablet Matches Full Dose in Thai Children

Author: Mark Mascolini


06 July 2013

In children who already had a viral load below 50 copies/mL with a protease inhibitor (PI) regimen, a 70% lopinavir/ritonavir maintenance dose was noninferior to the full dose in keeping viral load below 50 copies for 48 weeks, according to results of a multicenter Thai trial presented at IAS 2013.

However, children weighing 35 to 50 kg had more than a 3 times higher risk of virologic failure than children weighing less. In addition, twice as many children taking low-dose lopinavir/ritonavir had a lopinavir trough concentration below 1 mg/dL at week 48.

All children enrolled in this multicenter trial in Thailand weighed between 25 and 50 kg and were younger than 18. The study did not include children with resistance to PIs, those taking two PIs, and those taking medications that may interact with lopinavir/ritonavir, rifampin, nevirapine, or efavirenz. Children weighing 25 to 35 kg were randomized to the full dose (300/75 mg) or to 200/50 mg twice daily. Children weighing 35 to 50 kg were randomized to the full dose (400/100 mg) or to 300/75 mg twice daily.

A missing-data-equal-failure analysis determined that 90 of 98 children in the standard-dose group and 89 of 101 in the low-dose group had a viral load below 50 copies at week 48 (91.8% versus 88.1%, difference -3.7%, 95% confidence interval [CI] -12.0 to 0.46, P = 0.38). A missing-data-equal-censored analysis determined that 89 of 95 children in the standard-dose arm and 89 of 97 in the low-dose arm had a week-48 viral load below 50 copies (93.7% versus 91.8%, difference -1.9, 95% CI -9.4 to 5.5, P = 0.61).

Median lopinavir trough at week 48 measured 6.9 mg/dL in the standard-dose arm (range 0.3 to 20.4) and 5.2 mg/dL in the low-dose arm (range 0.2 to 11.8), a nonsignificant difference. Four children in the standard-dose group and 10 in the low-dose group had a lopinavir trough below 1 mg/dL at week 48.

Multivariate statistical analysis determined that poor adherence to therapy more than tripled the odds of virologic failure (adjusted odds ratio 3.3, 95% CI 1.3 to 8.1), as did weight between 35 to 50 kg versus less (adjusted odds ratio 3.6, 95% CI 1.2 to 10.8). At week 48, total cholesterol and triglyceride levels were significantly worse in the standard-dose group.

Source: T. Puthanakit, P. Suntarattiwong, P. Sangkla, et al. A randomized study comparing low dose versus standard dose lopinavir/ritonavir among HIV-infected children with virological suppression. 7th IAS Conference on HIV Pathogenesis, Treatment and Prevention, June 30-July 3, 2013, Kuala Lumpur. Abstract MOAB0101.

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