Chemical properties-dissolution relationship. IV. Behaviour in solution of the diclofenac/N-(2-hydroxyethyl) pyrrolidine salt (DHEP).

The behaviour in solution of the salt formed between diclofenac and N-(2-hydroxyethyl) pyrrolidine (DHEP) was examined. This salt is more soluble and dissolves more rapidly than sodium diclofenac and tends to give rise to supersaturated solutions, that only slowly evolve to equilibrium. Above 35 mM of DHEP, the solutions show unexpected solubilization ability towards sparingly soluble materials. The faster plasma level found, when DHEP is administered per os, can be associated to this weak detergency. These properties make DHEP a suitable pharmaceutical form to prepare extemporary solutions for short term analgesic therapy.