Diclofenac

Diclofenac, as the sodium salt, is a benzeneacetic acid derivative, designated chemically as 2-[(2,6-dichlorophenyl)amino] benzeneacetic acid, monosodium or monopotassium salt.

Diclofenac, as the sodium salt, is a faintly yellowish white to light beige, virtually odorless, slightly hygroscopic crystalline powder. Molecular weights of the sodium salt is 318.14. 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 noctanol/water partition coefficient is 13.4 at pH 7.4 and 1,545 at pH 5.2. The salt has a single dissociation constant (pKa) of 4.0 + 0.2 at 25° C in water.