Qsymia capsule is a combination oral product comprised of
immediate-release phentermine hydrochloride (as the free base) and
extended-release topiramate. Qsymia contains phentermine hydrochloride, a
sympathomimetic amine anorectic and topiramate, a sulfamate-substituted
monosaccharide related to fructose antiepileptic drug.
The chemical name of phentermine hydrochloride is
α,α-dimethylphenethylamine hydrochloride. The molecular formula is C10H15N•HCl
and its molecular weight is 185.7 (hydrochloride salt) or 149.2 (free base).
Phentermine hydrochloride is a white, odorless, hygroscopic, crystalline powder
that is soluble in water, methanol and ethanol. Its structural formula is:
2,3:4,5-di-O-isopropylidene-β-D-fructopyranose sulfamate. The molecular
formula is C12H21NO8S and its molecular weight
is 339.4. Topiramate is a white to off-white crystalline powder with a bitter
taste. It is freely soluble in methanol and acetone, sparingly soluble in pH 9
to pH 12 aqueous solutions and slightly soluble in pH 1 to pH 8 aqueous
solutions. Its structural formula is:
Qsymia is available in four dosage
- Qsymia 3.75 mg/23mg (phentermine 3.75 mg and topiramate 23
mg extended-release) capsules;
- Qsymia 7.5 mg/46 mg (phentermine 7.5 mg and topiramate 46 mg
- Qsymia 11.25 mg/69 mg (phentermine 11.25 mg and topiramate
69 mg extended-release) capsules;
- Qsymia 15 mg/92 mg (phentermine 15 mg and topiramate 92 mg
Each capsule contains the
following inactive ingredients: methylcellulose, sucrose, starch, microcrystalline
cellulose, ethylcellulose, povidone, gelatin, talc, titanium dioxide, FD&C
Blue #1, FD&C Red #3, FD&C Yellow #5 and #6, and pharmaceutical black
and white inks.
Last reviewed on RxList: 7/30/2012
This monograph has been modified to include the generic and brand name in many instances.