Diclofenac solid dosage forms

T. Kubala, B. Gamblhir, and J. I. Borst, A specific stability indicating HPLC method to determine diclofenac in raw materials and pharmaceutical solid dosage forms, Drug Dev. Ind. Pharm, 19 749(1993). 

The stability, both chemical and physical, of a drug may be enhanced or retarded by salt formation. For example, solid dosage forms of diclofenac contain salt forms rather than the less stable free acid. Although salt formation may result in improved dissolution rate and bioavailability of a poorly water-soluble compound, the preparation of stable salt forms for some drugs may not be feasible and the free acid or base forms may be preferred. For example, the base form of a-pentyl-3-(2-quinolinylmethoxy)benzenemethanol was selected for dosage form design because of the physical instability of its hydrochloride salt. ... 

---