DESCRIPTION

Topiramate is a sulfamate-substituted monosaccharide. Topiramate Tablets are available as 25 mg, 50 mg, 100 mg, and 200 mg round tablets for oral administration.

Topiramate USP is a white crystalline powder with a bitter taste. Topiramate USP is most soluble in alkaline solutions containing sodium hydroxide or sodium phosphate and having a pH of 9 to 10. It is freely soluble in acetone, chloroform, dimethylsulfoxide, and ethanol. The solubility in water is 9.8 mg/mL. Its saturated solution has a pH of 6.3. Topiramate USP has the molecular formula C12H21NO8S and a molecular weight of 339.37. Topiramate USP is designated chemically as 2,3:4,5-Di-O-isopropylidene-β-Dfructopyranose sulfamate and has the following structural formula:

Topiramate tablets contain the following inactive ingredients: lactose monohydrate, microcrystalline cellulose, pre-gelatinized starch, lactose monohydrate, sodium starch glycolate, magnesium stearate, opadry white (titanium dioxide, hypromellose 3cp, hypromellose 6cp, PEG 400, polysorbate 80) for 25 mg tablets, opadry yellow (titanium dioxide, hypromellose 3cp, hypromellose 6cp, PEG 400, polysorbate 80, iron oxide yellow) for 50 mg tablets, opadry yellow (hypromellose 3cp, hypromellose 6cp titanium dioxide, PEG 400, iron oxide yellow, polysorbate 80, iron oxide red) for 100 mg tablets and), opadry pink (titanium dioxide, hypromellose 6cp, PEG 400, iron oxide red) for 200 mg tablets.

CLINICAL PHARMACOLOGY

Mechanism of Action

The precise mechanisms by which topiramate exerts its anticonvulsant effects are unknown; however, preclinical studies have revealed four properties that may contribute to topiramate's efficacy for epilepsy. Electrophysiological and biochemical evidence suggests that topiramate, at pharmacologically relevant concentrations, blocks voltage-dependent sodium channels, augments the activity of the neurotransm