Belviq (lorcaserin HCl tablets; Arena Pharmaceuticals and Eisai) and Qsymia (phentermine and topiramate extended-release capsules; Vivus) have recently been approved by the FDA as an addition to a reduced-calorie diet and exercise, for chronic weight management in adult patients with an initial BMI of >30kg/m2 , or >27kg/m2 in the presence of at least one weight-related comorbid condition (e.g., hypertension, dyslipidemia, type 2 diabetes).

Lorcaserin is a serotonin 2C receptor agonist and is thought to decrease food consumption and promote satiety by selectively activating the serotonin receptors in the brain. It works similarly and has a similar chemical structure to fenfluramine, which was discontinued in 1997 due to cardiac side effects. But unlike fenfluramine, lorcaserin works more selectively and has NOT shown any harmful heart effects.

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A pivotal study that led to the approval of Belviq was the BLOOM trial (Behavioral Modification and Lorcaserin for Overweight and Obesity Management), which showed that 47.5% of patients in the lorcaserin group had lost 5% or more of their body weight and 22.6% lost more than 10% of their baseline weight, compared to 20.3% and 7.7% in the placebo group, respectively.8 Also, in Year 1, lorcaserin significantly decreased waist circumference, BMI, glycemic parameters, high-sensitivity C-reactive protein, fibrinogen levels, total cholesterol, LDL cholesterol, and triglyceride levels compared to placebo. Heart rate and blood pressure slightly decreased as well compared to placebo. Quality of life increased in both groups, with a greater improvement in the lorcaserin group. The most commonly reported side effects included headache, nausea, dry mouth, fatigue, dizziness, vomiting, and urinary tract infections. Belviq will not be available immediately due to time needed for DEA scheduling requirements.

Qsymia9 (VIVUS) is a combination of phentermine and topiramate. Phentermine is a dopaminergic agent thought to suppress appetite by triggering the release of norepinephrine in the brain. The second component of Qsymia, topiramate, is an antiseizure/migraine drug. Its mechanism of action in chronic weight management is unknown, but it is thought to suppress the appetite and enhance satiety.

Two pivotal studies that led to the approval of Qsymia are the EQUIP trial and the CONQUER trial. In the EQUIP trial, or the Controlled-Release Phentermine/Topiramate in Severely Obese Adults: A Randomized Controlled Trial, the average weight loss was 10.9% for patients on Qsymia 15mg/92mg and 1.6% for placebo (P<0.0001).10 One year of therapy with Qsymia resulted in relative improvement over placebo in several risk factors associated with obesity with the exception of heart rate.9 The most common side effects reported were paresthesia, dizziness, dysgeusia, insomnia, constipation, and dry mouth. In the CONQUER trial, or the Effects of Low-dose, Controlled-release, Phentermine Plus Topiramate Combination on Weight and Associated Comorbidities in Overweight and Obese Adults study, the average weight loss was 9.8% for patients on Qsymia 15mg/92mg, 7.8% for Qsymia 7.5mg/46mg and 1.2% for placebo (P<0.0001).11 Qsymia is expected to be available by the fourth quarter of 2012.