Effect of Phentermine on Weight Loss in the Obese in an Active Clinical Practice

Presentation Number: SUN 635
Date of Presentation: April 2nd, 2017

Erlin Marte*1, Rahil Ahmed1, Husam Ghanim1 and Paresh Dandona2
1State University of New York at Buffalo, Buffalo, NY, 2Diabetes and Endocrinology Center of Western New York, Buffalo, NY


In view of the rising tide of obesity and the high cost of the newer anti-obesity drugs, we have carried out a retrospective analysis of the effect of phentermine, the oldest licensed anti-obesity drug in the pharmacopeia, in our clinical practice. The study compared the magnitude of its effects in patients with and without diabetes and the occurrence of side effects like palpitation in active clinical practice. Out of 97 obese patients (Body weight=110±25 Kg) who were prescribed phentermine at a dose between 30-37.5 mg daily for about 6±1 months in our practice, 16 patients did not respond (<1Kg change). In the responders (n=81), the overall fall in body weight was 7.2±3.7Kg or 6.4±3.1% (P<0.05) with a fall in systolic blood pressure (SBP) of 3.4±1.6 mmHg (P<0.05) and diastolic blood pressure (DBP) of 1.6±1.3 mmHg (NS). When patients were stratified according to their diabetes status, the mean weight loss in non-diabetics (n=32) was 10.4±5.4 Kg (P<0.001) while SBP and DBP fell by 6.2±3.3 (p=0.09) and 1.4±1.8 mm (NS) respectively. Among patients with diabetes, weight loss was 4.1±2.4 Kg (p=0.06) in those with HbA1c >6.5% (n=16), 3.2±1.6 Kg (p=0.09) in those with HbA1c between 6.0 to 6.5% (n=12) and 7.4±4 kg (p<0.01) in those with HbA1c < 6% (n=21). Blood pressure did not change significantly in any of the diabetes subgroups. There was a slight and non-significant increase in the heart rate in obese patients without diabetes by <2±1 bpm and in patients with diabetes by 5±4 bpm. Two patients complained of moderate to severe palpitation and had to stop the drug; one of them had a heart rate of 140 (sinus tachycardia). HbA1c levels did not change significantly with the use of phentermine. We conclude that in a real life setting, the use of phentermine is associated with a significant weight loss and a fall in SBP without significant systemic side effects. The magnitude of fall is significantly lower in patients with diabetes. These results are important considering the fear of side effects currently in the minds of physicians, on the one hand, and the expense of the novel anti-obesity drugs on the other.


Nothing to Disclose: EM, RA, HG, PD