The indication is for use as additional therapy along with a reduced-calorie diet and increased physical activity in youth with obesity, defined as a body mass index of the 95th percentile or greater when standardized for age and sex.
Qsymia was first approved in July 2012 for chronic weight management in adults with an initial BMI of 30 kg/m2 or greater (obese) or 27 kg/m2 or greater (overweight) with one or more weight-related comorbidities, as an adjunct to lifestyle modification.
About 1 in 5 adolescents in the United States has obesity, according to the FDA.
The drug is the fourth to be approved for treating obesity in youth, along with liraglutide (Saxenda) and orlistat (Alli, Xenical), both approved down to age 12, and phentermine for those aged 16 and older.
The Qsymia approval was based on data from a phase 4 double-blind, placebo-controlled trial of 223 youth aged 12-16 with obesity who had not lost weight with lifestyle modifications. They were randomly assigned to Qsymia in doses of 7.5 mg phentermine/46 mg topiramate, 15 mg phentermine/92 mg topiramate, or placebo once daily, along with lifestyle counseling for all.
At 56 weeks, those taking the lower Qsymia dose lost an average of 4.8% of their BMI, and those on the higher dose lost 7.1%. In contrast, the placebo group gained about 3.3% of their BMI.
Because Qsymia increases the risk for oral clefts (lip and palate) in a fetus if taken during pregnancy, female patients should obtain negative pregnancy tests before starting the drug, take monthly pregnancy tests while on the drug, and use effective contraception throughout. Also because of the oral cleft risk, Qsymia is available only through an FDA program called a Risk Evaluation and Mitigation Strategy.
Additional potential adverse effects with Qsymia include increased heart rate and suicidal behavior/ideation. Patients should be advised to monitor for mood changes and discontinue the drug if depression or suicidal thoughts develop. The drug has also been linked to slowing of linear growth, so growth should be monitored in adolescents taking the drug, according to the FDA.
Qsymia is also associated with acute myopia, secondary angle closure glaucoma, visual problems, sleep disorders, cognitive impairment, metabolic acidosis, and decreased renal function.
The most common adverse reactions reported in the pediatric clinical trial included depression, dizziness, joint pain, fever, flu, and ankle sprain.
A version of this article first appeared on Medscape.com.