SPL Set ID: ffa46cb2-16e7-45f3-9940-5cb88d0cda9d

Lamotrigine extended-release tablets, USP (lamotrigine), an AED of the phenyltriazine class, is chemically unrelated to existing AEDs. Lamotrigine's chemical name is 3,5-diamino-6-(2,3-dichlorophenyl)- as -triazine, its molecular formula is C 9 H 7 N 5 Cl 2 , and its molecular weight is 256.09. Lamotrigine is a white to pale cream-colored powder and has a pK a of 5.7. Lamotrigine is very slightly soluble in water (0.17 mg/mL at 25°C) and slightly soluble in 0.1 M HCl (4.1 mg/mL at 25°C). The structural formula is: Lamotrigine extended-release tablets, USP are supplied for oral administration as 25-mg (light yellow to yellow), 50-mg (light green to green), 100-mg (light orange to orange), and 200-mg (light blue to blue) tablets. Each tablet contains the labeled amount of lamotrigine, USP and the following inactive ingredients: diethyl phthalate, ferric oxide black (50-mg tablet only), ferric oxide red (100-mg tablet only), ferric oxide yellow (25-mg, 50-mg and 100-mg tablets only), hypromellose, hypromellose phthalate, lactose monohydrate, lake of indigo carmine (200-mg tablet only), magnesium stearate, polyethylene glycol, talc, titanium dioxide. Lamotrigine extended-release tablets, USP contain a modified-release eroding formulation as the core. The tablets are coated with polymer to prevent release of drug in the acidic environment of the stomach. The combination of this and the modified-release core are designed to control the dissolution rate of lamotrigine over a period of approximately 12 to 15 hours, leading to a gradual increase in serum lamotrigine levels. Meets USP Dissolution test 3. 1