Amiloride hydrochloride is a potassium-sparing diuretic since it favors sodium excretion and potassium reabsorption. In the present study, urea, a well-known adductor for linear compounds was successfully employed for inclusion of amiloride hydrochloride-a substituted cyclic organic compound through a modified technique. Formation of urea inclusion compounds was confirmed by FTIR, DSC and XRD. The minimum amount of rapidly adductible endocyte (RAE) required for adduction of amiloride hydrochloride in urea was estimated by a modified Zimmerschied calorimetric method. Urea-AH-RAE inclusion compounds containing varying proportions of guests were prepared and their thermal behavior studied by DSC. The inclusion compounds were also found to exhibit high content uniformity and markedly improved dissolution profile as demonstrated by increased dissolution efficiency. Studies reveal the possibility of exploiting co-inclusion of the drug in urea host lattice for the dissolution enhancement. (Copyright) 2008 Wiley-Liss, Inc.