SPL Set ID: a63e19c0-a093-e896-e053-2a95a90a7ccd

Lamotrigine, USP, 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 USP, is a white to pale cream-colored powder and has a pK a of 5.7. Lamotrigine USP, 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 (yellow), 50 mg (green), 100 mg (beige), 200 mg (blue), 250 mg (purple) and 300 mg (gray) tablets. Each tablet contains the labeled amount of lamotrigine, USP and the following inactive ingredients: colloidal silicon dioxide, hypromellose, lactose monohydrate, macrogol, magnesium stearate, methacrylic acid copolymer dispersion, polyvinyl alcohol, talc, titanium dioxide and triethyl citrate. The 25 mg tablets also contain D&C Yellow No. 10 and FD&C Yellow No. 6. The 50 mg tablets also contain FD&C Blue No. 2 and iron oxide yellow. The 100 mg tablets also contain iron oxide red and iron oxide yellow. The 200 mg tablets also contain FD&C Blue No. 2. The 250 mg tablets also contain FD&C Blue No. 2 and FD&C Red No. 40. The 300 mg tablets also contain black iron oxide. Lamotrigine extended-release tablets, USP contain a modified-release eroding formulation as the core. The core tablets are coated with an enteric coat and have pore forming ingredient in the coat to enable a controlled release of the drug in the acidic environment of the stomach. The combinations of the modified-release core and the enteric coat 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. USP Dissolution Test pending. Structural Formula