Effects of phentermine / topiramate extended-release, phentermine, and placebo on ambulatory blood pressure monitoring in adults with overweight or obesity: A randomized, multicenter, double-blind study

Background

A fixed-dose combination of phentermine and extended-release topiramate (PHEN/TPM - approved for weight management) has demonstrated in-clinic reduction of blood pressure (BP). Ambulatory BP monitoring (ABPM) may be a better predictor of cardiovascular disease risk than in-clinic BP.

Methods

This randomized, multicenter, double-blind study enrolled 565 adults with overweight/obesity. Inclusion criteria included participants willing to wear ABPM device for 24 h. Exclusion criteria included screening blood pressure >140/90 mmHg and antihypertensive medications not stable for 3 months prior to randomization. Participants received placebo (n = 184), phentermine 30 mg; (n = 191), or PHEN 15 mg/TPM 92 mg; (n = 190). 24-hour ABPM was performed at baseline and at week 8. The primary endpoint was mean 24-h systolic BP (SBP) as measured by ABPM, in the per protocol population.

Results

Participants were mostly female (73.5 ​%) and White (81.6 ​%), with a mean age of 53.4 years; 32.4 ​% had no hypertension diagnosis or treatment, 62.5 ​% had hypertension using 0 to 2 antihypertensive medications, and 5.1 ​% had hypertension using ≥ 3 antihypertensive medications. Baseline mean SBP/diastolic BP (DBP) was 123.9/77.6 ​mmHg. At week 8, mean SBP change was −0.1 ​mmHg (placebo), +1.4 ​mmHg (phentermine 30 ​mg), and −3.3 ​mmHg (PHEN/TPM). Between-group difference for PHEN/TPM versus placebo was −3.2 ​mmHg (95 ​% CI: -5.48, -0.93 ​mmHg; p ​= ​0.0059). The between-group difference for PHEN/TPM versus phentermine 30 ​mg was −4.7 ​mmHg (95 ​% CI: −6.96, −2.45 ​mmHg; p ​< ​0.0001). Common (>2 ​% in any treatment group) adverse events (i.e., dry mouth, constipation, nausea, dizziness, paresthesia, dysgeusia, headache, COVID-19, urinary tract infection, insomnia, and anxiety) were mostly mild or moderate.

Conclusions

In this randomized, multicenter, double-blind ABPM study, PHEN/ TPM reduced SBP compared to either placebo or phentermine 30 mg (Funding: Vivus LLC; ClinicalTrials.gov: NCT05215418).