What guidelines support the use of Phentermine (Phentermine hydrochloride) for weight loss?

From the Guidelines

Phentermine should be used with lifestyle modifications for weight loss in adults with obesity or overweight with weight-related complications, as suggested by the AGA with a conditional recommendation and low-quality evidence 1. The use of phentermine for weight loss is supported by the American Gastroenterological Association (AGA) clinical practice guideline on pharmacological interventions for adults with obesity, which suggests using phentermine with lifestyle modifications compared to lifestyle modifications alone 1. Key considerations for the use of phentermine include:

• It is approved by the FDA for short-term use (12 weeks) but is often used off-label for longer durations due to the chronic nature of weight management 1.
• Phentermine should be avoided in patients with a history of cardiovascular disease, and blood pressure and heart rate should be monitored periodically while taking the medication 1.
• The recommended dosage of phentermine is 15 to 37.5 mg orally once daily in the morning, with common side effects including dry mouth, difficulty sleeping, dizziness, and irritability 1.
• Appropriate candidates for phentermine include patients with obesity who need assistance with appetite suppression, but it should be used with caution in patients with anxiety or insomnia 1. Overall, the use of phentermine for weight loss should be considered as part of a comprehensive program including diet and exercise, with careful monitoring of side effects and contraindications.

From the FDA Drug Label

Phentermine Hydrochloride is a sympathomimetic amine anorectic indicated as a short-term adjunct (a few weeks) in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index greater than or equal to 30 kg/m 2, or greater than or equal to 27 kg/m 2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia). The guideline supporting the use of phentermine for weight loss is as follows:

• Indication: Phentermine is indicated for short-term use in a regimen of weight reduction based on exercise, behavioral modification, and caloric restriction.
• Patient Selection: Patients with an initial body mass index (BMI) greater than or equal to 30 kg/m^2, or greater than or equal to 27 kg/m^2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia) are eligible for phentermine use.
• Duration of Use: Phentermine should be used for a few weeks as a short-term adjunct in a weight reduction regimen.
• Concomitant Therapy: Phentermine should be used in conjunction with exercise, behavioral modification, and caloric restriction. 2

From the Research

Guideline for Phentermine Use in Weight Loss

• Phentermine is an anti-obesity medication that can be used for weight loss in combination with lifestyle modifications, such as a hypocaloric diet and increased physical activity 3, 4, 5, 6, 7.
• The medication has been shown to produce significant weight loss, with studies indicating a 10% loss of body weight 5, 6.
• Phentermine is generally well tolerated, with common adverse reactions including paresthesia, dizziness, dysgeusia, insomnia, constipation, and dry mouth 6.
• The medication can be used as an adjunct to diet and exercise for chronic weight management in obese or overweight adults with weight-related comorbidities 5, 6.

Patient Selection and Treatment Approach

• The decision to use phentermine should be based on a patient-specific approach, taking into account the individual's chronic conditions, comorbidities, and preferences 3, 4, 5.
• Phentermine should be used in conjunction with lifestyle modifications, such as a reduced-calorie diet and increased physical activity, to achieve optimal weight loss results 3, 4, 5, 6.
• Clinicians should carefully weigh the benefits and risks of phentermine use, particularly in patients with a history of cardiovascular disease or other comorbidities 3, 4, 7.

Efficacy and Safety

• Studies have shown that phentermine can produce significant weight loss, with a meta-analysis indicating a 6.8% placebo-subtracted weight reduction over 12 months 3.
• Phentermine has been associated with improvements in cardiometabolic parameters, including reductions in waist circumference, fasting triglycerides, and fasting glucose 6.
• While phentermine is generally well tolerated, large-scale observational studies are needed to fully assess its long-term safety and efficacy 7.