Gabapentin is 1-(aminomethyl)cyclohexaneacetic acid; y-amino-2-cyclohexyl-butyric acid with a molecular formula of C₉H₁₇NO₂ and a molecular weight of 171.24. The structural formula is:

Gabapentin is a white to off-white crystalline solid with a pKa1 of 3.7 and a pKa2 of 10.7. It is freely soluble in water and acidic and basic solutions. The log of the partition coefficient (n-octanol/ 0.05M phosphate buffer) at pH 7.4 is -1.25.

GRALISE is supplied as tablets containing 300 mg or 600 mg of gabapentin. GRALISE tablets swell in gastric fluid and gradually release gabapentin. Each 300 mg tablet contains the inactive ingredients copovidone, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene oxide, and Opadry® II white. Opadry® II white contains polyvinyl alcohol, titanium dioxide, talc, polyethylene glycol 3350, and lecithin (soya). Each 600 mg tablet contains the inactive ingredients copovidone, hypromellose, magnesium stearate, polyethylene oxide, and Opadry® II beige. Opadry® II beige contains polyvinyl alcohol, titanium dioxide, talc, polyethylene glycol 3350, iron oxide yellow, and iron oxide red.

Last reviewed on RxList: 8/16/2012
This monograph has been modified to include the generic and brand name in many instances.