Two new weight-loss drugs available for patients with diabetes

With the FDA approval and coverage of new prescription weight-loss drugs last year, healthcare professionals have two more options to consider when treating obesity.

According to the Centers for Disease Control and Prevention, 2009–2010 saw this major public health challenge affect more than one-third of adults and almost 17% of children and adolescents.

Obesity places individuals at increased risk for several chronic diseases, including hypertension, dyslipidemia, and type 2 diabetes mellitus. Weight loss in patients with diabetes has been associated with improved glycemic control and improved lipid profiles.

Although healthcare professionals have counseled patients about diet and exercise as the main approach for weight reduction, some patients continue to struggle and may seek alternative methods beyond caloric restriction and the treadmill.

Lorcaserin approval

In June 2012, FDA approved lorcaserin (Belviq, Arena Pharmaceuticals/ Eisai), a serotonin 2C receptor agonist, indicated as an adjunct to diet and increased physical activity for chronic weight management in adult patients who are obese or overweight and have at least one weight-related comorbidity (e.g., hypertension, dyslipidemia, type 2 diabetes).  This was the first weight-loss prescription approved in 13 years, since FDA approved orlistat, a reversible inhibitor of gastrointestinal lipases.

Lorcaserin was approved on the basis of data from three randomized, double-blind, placebo-controlled trials lasting from 52 to 104 weeks. At one year, approximately 47% of patients without diabetes in studies 1 and 2 lost ≥5% body weight, and approximately 22% achieved a loss of 10% body weight or more. In the third study, 37.5% of patients with type 2 diabetes mellitus lost ≥5% body weight and about 16% achieved a loss of 10% body weight or more.

“The average weight loss at one year from baseline ranged from 3% to 3.7% for patients taking lorcaserin,” wrote Elizabeth M. Kelly, PharmD, and colleagues in the October issue of the Journal of Managed Care Pharmacy.

Safety concerns outlined in lorcaserin’s prescribing information include serotonin syndrome, valvular heart disease, cognitive impairment, psychiatric disorders, hypoglycemia, heart rate decreases, hematological changes, and moderate prolactin elevation.

Phentermine/topiramate approval

In July 2012, FDA approved another prescription weight-loss drug, phentermine/topiramate extended-release capsules (Qsymia, Vivus), a combination of a sympathomimetic amine anorectic and an antiepileptic drug, to be used as an adjunct to diet and increased physical activity for chronic weight management in adult patients who are obese or overweight and have at least one weight-related comorbidity (e.g., hypertension, type 2 diabetes, or dyslipidemia).

The combination weight-loss drug was approved on the basis of results from two randomized, double-blind, placebo-controlled studies. In study 1, obese patients were treated for 1 year with 3.75-mg/23-mg phentermine/topiramate, 15-mg/92-mg phentermine/topiramate, or placebo. In the second study, overweight patients with two or more significant comorbidities were randomized to receive for one year 7.5-mg/46-mg phentermine/topiramate, 15-mg/92-mg phentermine/topiramate, or placebo.

At the end of one year, significantly more patients receiving phentermine/topiramate vs. placebo achieved 5% and 10% weight loss. In study 1 of the lower-dose group (3.75-mg/23-mg phentermine/topiramate), 45% achieved 5% body weight loss and 19% reached the goal of 10% body-weight loss. In the high-dose group of study 1 (15-mg/92-mg phentermine/topiramate), 67% achieved 5% body weight loss and 47% achieved 10% body weight loss. In study 2 of the lower-dose group (7.5-mg/46-mg phentermine/topiramate), 62% achieved 5% body weight loss and 37% achieved 10% body weight loss. Among the higher-dose group in study 2 (15-mg/92-mg phentermine/topiramate), 70% had 5% body-weight loss and 48% had 10% body-weight loss at one year.

“Those [patients] taking phentermine/topiramate on average lost a range of 6.7% (lowest dose) to 8.9% (recommended dose),” Kelly and colleagues wrote in the October 2013 study published in the Journal of Managed Care Pharmacy.

In the prescribing information for the drug, warnings and precautions included fetal toxicity, increase in heart rate, suicidal behavior and ideation, acute myopia and secondary angle closure glaucoma, mood and sleep disorders, cognitive impairment, metabolic acidosis, elevated creatinine, and hypoglycemia.

“Statistically significant improvements in blood pressure, cholesterol, and triglycerides were observed among diabetic patients taking phentermine/topiramate but not lorcaserin,” Kelly and colleagues wrote. “However, in the BLOSSOM trial, more patients assigned to lorcaserin twice daily group versus placebo decreased total daily use of medications to treat hypertensions and dyslipidemia.”

Kelly and colleagues noted that comparative safety and efficacy and drug costs are important issues to consider when evaluating new therapies for obesity. Both side-effect profiles and contraindications may limit the use of prescription weight-loss drugs.