Description
Diclofenac, as the sodium salt, is a benzene-acetic acid derivative, designated chemically as Sodium [o-(2,6-dichloroanilino)phenyl]acetate. The molecular weight is 318.13. Its molecular formula is C14H10Cl2NNaO2 and it has the following structural formula:
Diclofenac sodium USP, is a faintly yellowish white to light beige, virtually odorless, slightly hygroscopic crystalline powder. The molecular weight of the sodium salt is 318.13. It is freely soluble in methanol, soluble in ethanol, and practically insoluble in chloroform and in dilute acid. Diclofenac sodium is sparingly soluble in water. The n-octanol/water partition coefficient is 13.4 at pH 7.4 and 1545 at pH 5.2. The sodium salt has a single dissociation constant (pKa) of 4.0 ± 0.2 at 25°C in water.
Each delayed-release tablet for oral administration contains 50 mg or 75 mg of diclofenac sodium. In addition, each tablet contains the following inactive ingredients: crospovidone, FD & C Blue No. 2 Aluminum Lake (50 mg), FD & C Red No. 40 (75 mg), FD & C Yellow No. 6, hypromellose, iron oxide yellow (50 mg), lactose monohydrate, magnesium stearate, methacrylic acid copolymer, microcrystalline cellulose, polyethylene glycol, povidone, simethicone, sodium hydroxide, talc and titanium dioxide.