Some effects of urea on drug dissolution

Abstract

Solubilities and dissolution rates of salicylic acid have been determined in urea solutions at different pH values. Solubilities increased with pH and urea concentration; a solubilization mechanism was considered to be operating. The solubilization effect of urea was greatest on the non-ionized moieties of the solute. Dissolution rates of salicylic acid increased with pH and urea concentration. The increase in dissolution rate paralleled increases in solubility. The role of solubilizing effect in the enhancement of dissolution rate by urea is discussed.