Isentress (raltegravir), Merck’s integrase inhibitor, is now approved for HIV-positive children 2 years of age and older, according to a U.S. Food and Drug Administration (FDA) announcement. In addition, 100 milligram (mg) and 25 mg chewable tablets were approved for use in children requiring antiretroviral (ARV) therapy involving Isentress. 

The approval recommendation is based, in part, on the successful completion of a clinical trial involving 126 ARV therapy-experienced children and adolescents between the ages of 2 and 18. All study volunteers received Isentress in combination with other ARVs. 

Of the 126 patients, 96 received the recommended dose of Isentress. In these 96 children and adolescents, the frequency, type and severity of drug-related side effects through 24 weeks of treatment were comparable to those observed in Isentress clinical trials involving adults.

Ninety-three of the study volunteers completed all six months of therapy; three discontinued because of non-compliance. At week 24, 54 percent had undetectable viral loads. The average CD4 count increase during the six-month follow-up period was 119 cells. 

Isentress dosing for children is based on age and weight. Though Isentress is approved for children 2 years old and older, it should not be used by those weighing less than 22 pounds (10 kilograms). If the chewable tablets are used, the total daily dose should not exceed 300 mg used twice daily. If the traditional 400 mg Isentress tablets are used—recommended for all children 12 years old and older and an option for children between 6 and 12 years old weighing at least 55 pounds (25 kilograms)—the dose should not exceed one tablet used twice daily. 

It is important to note that the Isentress chewable tablets contain phenylalanine, a component of the sugar substitute aspartame. The FDA notes that phenylalanine can be harmful to patients with phenylketonuria, a birth defect that can lead to a variety of health problems and requires a diet that limits the intake of phenylalanine. It is important to note, however, that babies born in the United States are routinely screened for phenylketonuria soon after birth.