Assessment of the safety and efficacy of sodium pentaborate pentahydrate in individuals with overweight and obesity: a randomized, double-blind, placebo-controlled, phase 1/2 dose-finding trial

The present study aimed to examine the short-term safety and tolerability of sodium pentaborate pentahydrate (NaB) and to explore preliminary efficacy and dose selection as secondary objectives in individuals with overweight or obesity. In this randomized, double-blind, placebo-controlled, phase 1/2 trial, conducted from July 2024 to January 2025, 177 adults with overweight or obesity were randomized, of whom 116 completed the 12-week trial. Participants received placebo or NaB at doses of 200, 400, 600, 800, or 1,000 mg for 12 weeks, alongside a standardized diet and exercise programme. The primary safety objective was to investigate short-term safety and tolerability through adverse events, hypoglycaemic episodes, gastrointestinal adverse events, and changes in haematological and biochemical parameters. The primary exploratory efficacy outcome was percentage change in body weight from baseline to week 12. Secondary and exploratory efficacy outcomes included body weight, body mass index (BMI), waist and hip circumferences, waist-to-hip ratio, glycaemic markers, lipid parameters, and blood pressure. Baseline characteristics were broadly similar across groups (all p ≥ 0.05), and no major short-term safety signal was observed. Mean body weight decreased in the 400 mg (-2.6 kg), 600 mg (-1.2 kg), and 1,000 mg groups (-3.1 kg). Compared with placebo, the 1,000 mg dose resulted in the largest reductions in body weight (mean difference, -2.30 kg; p = 0.01) and BMI (mean difference, -0.85 kg/m2; p = 0.02). The 1,000 mg dose showed preliminary efficacy for reducing body weight and BMI over 12 weeks compared with placebo, with no major short-term safety signal and no clinically meaningful changes in renal, hepatic, or haematological markers. All reported adverse events were mild. These short-term findings are exploratory and require confirmation in future phase 3 trials with extended follow-up to investigate long-term safety and efficacy.