Effect of Phentermine on Hepatic Steatosis in Bariatric Surgery: A Pilot Study

OBJECTIVE: Hepatic steatosis is associated with increased surgical complications in bariatric surgery patients. We aimed to evaluate the effect of phentermine in reducing hepatic steatosis, adipose tissue, and surgical complications in patients undergoing bariatric surgery. METHODS: This was a two-arm, double-blind, randomized, controlled pilot trial of 64 adult subjects with BMI >35 kg/m² selected for bariatric surgery randomized into phentermine group (15 mg once daily) or placebo group for 8 weeks. Both groups adhered to a hypocaloric diet (500 calories/day) and an individualized exercise program. The primary endpoint was reducing the frequency of hepatic steatosis measured by ultrasound and reducing adipose tissue through fat mass in total kilograms or percentage. Key secondary points were the prevalence of surgical complications. Baseline and final biochemical parameters and blood pressure too were assessments. RESULTS: In the phentermine group, the frequency of hepatic steatosis decreased by 19%, and the percentage of patients with a normal ultrasound increased from 9% to 28% (p = 0.05). Likewise, the decrease in fat mass in kilograms was more significant in the phentermine group (56.1 kg vs. 51.8 kg, p = 0.02). A significant reduction in the HOMA-IR index was observed regardless of weight loss. No differences in surgical complications were observed between groups. Phentermine was well-tolerated; no differences were observed in the frequency of adverse events between the groups. CONCLUSIONS: Phentermine decreased the proportion of individuals with hepatic steatosis by 19% and promoted a more significant fat mass loss in kilograms among candidates for bariatric surgery.