A randomized, placebo-controlled crossover trial of phentermine-topiramate ER in patients with binge-eating disorder and bulimia nervosa.
Level 2 - randomized trial
Randomized, placebo-controlled crossover trial
PubMed 31721257 · doi:10.1002/eat.23192
What was done
Twenty-two adults (18 with binge-eating disorder and 4 with bulimia nervosa; 96% female, mean age 42.9 years, mean BMI 31.1 kg/m²) participated in a randomized, placebo-controlled crossover trial. Participants received 12 weeks of phentermine/topiramate extended-release (titrated from 3.75 mg/23 mg to 15 mg/92 mg) or placebo, followed by a 2-week washout period and a 12-week crossover. The primary outcome was objective binge-eating (OBE) days per 4 weeks; secondary outcomes included binge abstinence, weight change, and vital sign changes, assessed via mixed-effects models.
What was found
OBE days per 4 weeks decreased from 16.2 (SD = 7.8) at baseline to 4.2 (SD = 8.4) with phentermine/topiramate ER versus 13.2 (SD = 9.1) with placebo (p < .0001). Full binge abstinence was achieved in 63.6% of participants on the drug versus 9.1% on placebo (p < .0001). Average weight change was -5.8 kg on active drug versus +0.4 kg on placebo. Drop-out occurred in 2 participants (9%) per phase, with minimal vital sign changes and few side effects reported. Outcomes did not differ significantly between BED and BN subgroups.
Why it matters
This represents the first randomized controlled trial evaluating phentermine/topiramate ER for binge-eating disorder and bulimia nervosa, demonstrating short-term efficacy for reducing binge episodes and body weight.
Limits
The trial had a very small sample size (n = 22) and was predominantly female (96%). With only 4 participants diagnosed with bulimia nervosa, the trial was underpowered to establish safety or efficacy in this subgroup. The 12-week treatment duration also does not address long-term durability or recurrence following discontinuation.
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- supports A clinical trial evaluating Qsymia in patients with binge eating disorder and bulimia demonstrated a 63% abstinence rate in the treatment group compared to approximately 6% in the control group.