Phentermine & Topiramate Combination (also called Qsymia)
Qsymia is made from two old drugs. One of these drugs was contained in the infamous Wyeth diet pill, Fen-Phen. The other drug is Johnson & Johnson’s Topamax, or topiramate, originally developed for migraines and epileptic seizures, which also has a history of side effects.
HOW DOES QSYMIA WORK?
Qsymia is a proprietary drug formulation that incorporates the active ingredients from two previously approved products with proven weight loss properties: phentermine and topiramate. By combining the activity of each of these compounds in a, once-daily, low-dose capsule formulation, Qsymia simultaneously targets appetite and satiety. As such, Qsymia appears to induce significantly greater weight loss than either individual compound.
Phentermine has been available for treating obesity since the 1950s and is still the most widely prescribed weight loss drug. Topiramate was approved in 1996 for treating epilepsy, and more recently as a prophylactic for migraine. The rationale behind Qsymia is to expand topiramate’s therapeutic window by using a low dose and combining it with phentermine, which acts via a different mechanism. Topiramate increases the sensation of fullness or satiety, while phentermine is noradrenergic and non-serotonergic, and reduces appetite.
Phentermine is released into the body immediately and helps reduce appetite. It was a major component of the recalled diet drug fen-phen, which was linked to heart and lung problems and was taken off the market ion 1997. Topiramate is time released and used in very low doses to give patients a feeling of satiety. Originally an epilepsy drug, topiramate is also used to help prevent migraine headaches.
Qsymia is indicated as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in adults with an initial body mass index (BMI) of:
- 30 kg/m2 or greater (obese) or
- 27 kg/m2 or greater (overweight) in the presence of at least one weight-related medical condition such as high blood pressure, type 2 diabetes, or high cholesterol
Limitations of Use:
- The effect of Qsymia on cardiovascular morbidity and mortality has not been established
- The safety and effectiveness of Qsymia in combination with other products intended for weight loss, including prescription and over-the-counter drugs, and herbal preparations, have not been established
Qsymia must not be used by women who are pregnant; by patients with eye problems (glaucoma); by patients who have been told they have an overactive thyroid; by patients taking a type of anti-depressant called MAOI; or by patients who are allergic to phentermine, topiramate, or any of the ingredients in Qsymia.
Qsymia can harm your unborn baby. If you take Qsymia while you are pregnant, your baby has a higher risk for birth defects called cleft lip and cleft palate. These defects can begin early in pregnancy, even before you know you are pregnant. You should have a negative pregnancy test before taking Qsymia and every month while taking Qsymia. Use effective birth control (contraception) consistently while taking Qsymia. Talk to your healthcare provider about how to prevent pregnancy. If you become pregnant while taking Qsymia, you should stop taking Qsymia immediately and contact your healthcare provider right away.
Qsymia can increase your heart rate at rest. Tell your healthcare provider if you experience, while at rest, a racing or pounding feeling in your chest lasting several minutes when taking Qsymia.
Topiramate, a component of Qsymia, increases the risk of suicidal thoughts or behavior in patients. Pay attention to any changes and call your healthcare provider right away if you have any of these symptoms, especially if they are new, worse, or worry you: thoughts about suicide or dying, attempts to commit suicide, new or worse depression, or other unusual changes in behavior or mood.
Eye problems, such as glaucoma (an increased pressure in the eye due to fluid blockage), may develop while you are taking Qsymia. You should call your healthcare provider if you experience any sudden decrease in vision, with or without eye pain and redness, and stop taking Qsymia immediately. These problems can lead to permanent vision loss if not treated.
Qsymia may affect how you think and is associated with difficulty with attention and concentration, memory and word-finding. Therefore, use caution when operating hazardous machinery, including automobiles.
Weight loss may increase the risk of low blood sugar in patients with type 2 diabetes mellitus treated with insulin. Your healthcare provider may adjust your antidiabetic medicines while you are taking Qsymia.
The most common side effects seen in Qsymia clinical studies were tingling in the hands and feet, dizziness, change in taste, trouble sleeping, constipation, and dry mouth.
Results of the Qsymia study (EQUIP)
The EQUIP study was designed to look at the effect of Qnexa on morbidly obese patients, that is, those patients with a baseline BMI of 35 or greater. In total, 1267 obese people at 93 sites in the US were tested. The average baseline BMI in the EQUIP study was 42.1. A review of results by baseline BMI show a consistent effect across a broad range of patients based on starting body weight. On an ITT-LOCF basis, the overall percent weight loss in the EQUIP study was 11% for patients on full dose Qnexa, as compared to 1.6% for the placebo group. The CONQUER study included 2,487 overweight and obese patients with high blood pressure, high cholesterol or type 2 diabetes across 93 centers in the US.
Key findings from the EQUIP (full dose) and CONQUER (half dose0 studies include:
- Average weight loss of 14.7% (37 lbs) was achieved by patients treated with Qnexa for 56 weeks in the EQUIP study
- Average weight loss of 8.4% (19 lbs) was achieved by patients treated with Qnexa for 56 weeks in the CONQUER study
- Average weight loss of 5.1% (18 lbs) was achieved by patients treated with Qnexa for 56 weeks in the low dose EQUATE study
- Significant improvements in cardiovascular, metabolic and inflammatory risk factors among patients treated with Qnexa
- FDA efficacy benchmarks for weight loss agents were exceeded at all three doses of Qnexa evaluated in the clinical studies
- Completion rates up to 69% were significantly higher than placebo at all three doses of Qnexa, indicating favorable tolerability