From the Guidelines
Phentermine is a prescription medication used for short-term weight loss in overweight or obese patients when combined with diet and exercise, and it should be used with caution due to potential side effects and interactions, as recommended by the most recent guidelines 1.
Key Points
- Phentermine belongs to the class of drugs known as sympathomimetic amines and works by stimulating the central nervous system to suppress appetite.
- Typically prescribed at doses of 15-37.5 mg once daily, taken before breakfast or 1-2 hours after breakfast, phentermine should generally be used for no more than 12 weeks due to potential for tolerance and dependence.
- Common side effects include dry mouth, insomnia, constipation, increased heart rate, and elevated blood pressure.
- Phentermine is contraindicated in patients with cardiovascular disease, hyperthyroidism, glaucoma, history of drug abuse, or during pregnancy.
- As a controlled substance (Schedule IV), phentermine has potential for abuse and should be used carefully under medical supervision, with monitoring of blood pressure and heart rate periodically while taking the medication 1.
Important Considerations
- The use of phentermine should be individualized, taking into account the patient's medical history, current medications, and potential risks and benefits, as suggested by the AGA clinical practice guideline on pharmacological interventions for adults with obesity 1.
- Patients who place a high value on the potential weight loss benefit and low value on adverse effects may reasonably choose treatment with phentermine, but should be aware of the potential risks and interactions 1.
- The medication should be used in conjunction with lifestyle modifications, including diet and exercise, to achieve optimal weight loss results, as recommended by the guidelines on obesity and weight management for the prevention and treatment of type 2 diabetes 1.
From the FDA Drug Label
Phentermine hydrochloride is a sympathomimetic amine anorectic. Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, amphetamine (d- and dll-amphetamine). Drugs of this class used in obesity are commonly known as “anorectics” or “anorexigenics.
Phentermine is a sympathomimetic amine used as an anorectic for the treatment of obesity. It has pharmacologic activity similar to amphetamine and is commonly known as an anorectic or anorexigenic 2, 2, 2.
- Key characteristics:
- Sympathomimetic amine
- Anorectic
- Used in obesity treatment
- Similar to amphetamine
- Known as anorectic or anorexigenic
- Chemical name: α,α,-dimethylphenethylamine hydrochloride 2.
From the Research
Definition and Overview of Phentermine
- Phentermine is an anti-obesity medication used for weight loss in adults 3, 4.
- It is commonly prescribed in combination with other medications, such as topiramate, orlistat, or as a single agent 3, 5.
- Phentermine works by suppressing appetite and increasing feelings of fullness, leading to weight loss 4.
Efficacy and Safety of Phentermine
- Studies have shown that phentermine can result in significant weight loss, with a placebo-subtracted weight reduction of up to 6.8% 3.
- Phentermine is generally well-tolerated, with no increased risk of cardiovascular events or elevations in blood pressure 4.
- However, there is limited rigorous research to support its efficacy and safety in long-term treatment 4.
Comparison with Other Anti-Obesity Medications
- Phentermine has been compared to other anti-obesity medications, such as orlistat, liraglutide, and semaglutide, in terms of efficacy and safety 6.
- Each medication has its own benefits and side effects, and treatment approaches should be tailored to individual patients 6, 7.
- Phentermine is one of the seven FDA-approved anti-obesity medications, and it should be prescribed with the intention of long-term use 7.