VIVUS has started patient enrolment in a Phase IV clinical trial of Qsymia (phentermine and topiramate, extended-release) capsules in obese adolescents aged between 12 and 17 years.

Qsymia holds US regulatory approval as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management.

It is designed for adults with an initial body mass index (BMI) of 30kg/m2 or greater (obese), or 27kg/m2 or greater in the presence of at least one weight-related medical condition such as high blood pressure, type 2 diabetes or high cholesterol.

This post-marketing Phase IV trial will investigate the safety, tolerability and efficacy of the drug in approximately 200 subjects at around 20 clinical sites across the US. It is a randomised, double-blind, placebo-controlled, parallel-design study that is required by the US Food and Drug Administration (FDA).

The primary endpoint of the trial is the mean percentage change in BMI in participants randomised 1:1:2 to daily mid or top-dose of Qsymia over 56 weeks, compared to placebo.

Subjects will have to follow a reduced-calorie diet and adopt a lifestyle modification programme that includes physical activity, behavioural change and family support.

VIVUS CEO John Amos said: “A previously completed pharmacokinetic (PK) study of Qsymia in obese adolescents showed PK parameters consistent with those observed in the clinical trials conducted in obese adults.

“Qsymia has demonstrated significant clinical benefits in the treatment of obese and overweight adults. If successful, this Phase IV study could position Qsymia as an important new treatment option for millions of adolescents struggling with the near- and long-term challenges of obesity.”

Top-line data from the latest trial are set to be available in the second half of next year.