What is the use of Qsymia (phentermine and topiramate)?

From the Guidelines

Qsymia should be initiated at a starter dose of 3.75 mg/23 mg and titrated up to a target dose of 15 mg/92 mg, as long as the balance of benefit and risk is favorable for the individual patient, to maximize weight loss and minimize side effects. The medication is a combination of phentermine and topiramate, and its use should be considered in patients with obesity and migraines, as it may provide additional benefits for migraine headaches 1. When prescribing Qsymia, it is essential to consider the potential risks and benefits, including the risk of birth defects, and to counsel women of childbearing age on the importance of using effective contraception while taking the medication.

The American Gastroenterological Association (AGA) recommends the use of pharmacological agents, including Qsymia, in adults with obesity or overweight with weight-related complications who have had an inadequate response to lifestyle interventions 1. The AGA suggests using Qsymia with lifestyle modifications, compared with lifestyle modifications alone, and notes that it may be preferentially used in patients with comorbid migraines. However, Qsymia should be avoided in patients with a history of cardiovascular disease and uncontrolled hypertension, and blood pressure and heart rate should be monitored periodically while taking the medication.

Common side effects of Qsymia include tingling in hands and feet, dizziness, altered taste, insomnia, constipation, and dry mouth. The medication works by reducing appetite through multiple mechanisms in the brain, helping patients consume fewer calories while feeling satisfied. It is essential to monitor patients taking Qsymia for potential side effects and to adjust the dose as needed to minimize adverse effects. Additionally, patients should be counseled on the potential risks of teratogenicity and the importance of using reliable contraception while taking the medication.

In terms of dosing, the medication comes in four strengths, and patients usually start at the lowest dose and gradually increase to minimize side effects. After 12 weeks, if the patient has not lost at least 3% of their body weight, consideration should be given to discontinuation or further dose escalation, depending on tolerance, adverse effects, and patient preference 1. The target dose of 15 mg/92 mg should be used, as it has been shown to have superior efficacy compared with lower doses. However, the dose should be titrated carefully, and patients should be monitored closely for potential side effects.

From the FDA Drug Label

INDICATIONS AND USAGE 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 FDA drug label does not answer the question about Qsymia, as it only discusses Phentermine Hydrochloride 2.

From the Research

Qsymia Overview

• Qsymia is a combination of phentermine and extended-release topiramate, approved by the FDA for chronic weight management in obese adults and overweight adults with weight-related co-morbidities 3, 4.
• The medication is intended to be used in conjunction with a reduced-calorie diet and increased physical activity 4, 5.

Efficacy of Qsymia

• Clinical trials have shown that Qsymia can produce and sustain approximately 10% loss of body weight 3, 4.
• The efficacy of Qsymia is closely related to the dosage, with higher doses resulting in greater weight loss 6, 7.
• A systematic review and meta-analysis found that Qsymia therapy resulted in an average weight loss of 7.73 kg compared to placebo 7.

Safety of Qsymia

• Common adverse events associated with Qsymia include dysgeusia, paresthesia, dry mouth, disturbance in attention, irritability, hypoesthesia, constipation, and dizziness 6, 7.
• Qsymia has also been shown to reduce waist circumference, blood pressure, blood sugar levels, and lipid levels 7.
• However, Qsymia increases the risk of nervous system-related adverse events 7.

Clinical Trials

• The CONQUER trial, a 56-week phase 3 trial, found that Qsymia resulted in significant weight loss and improvements in cardiometabolic risk factors compared to placebo 6.
• Other clinical trials have also demonstrated the efficacy and safety of Qsymia for weight loss and weight management 3, 4, 5, 7.