Enhancement of dissolution rate of hydrochlorothiazide via solid dispersion

Solid dispersions of hydrochlorothiazide (1) in mannitol (2) and in dihydroxypropyltheophylline (3) were prepared by melting and solvent methods. For both systems, phase diagrams of simple eutectic type were obtained. A significant increase in dissolution rate was observed for 1/2 and 1/3 physical mixtures and solid dispersion as compared to pure drug. Solubility of 1 in 2 and in 3 solution at 27 degrees C and 37 degrees C was studied. At 37 degrees C the water solubility of the drug increased 3.7 times using 0.4 mol X 1(-1) 3. The solubilization of the drug by 3 in water was due to the formation 1 : 1 soluble complex. 1 tablets from physical mixtures and solid dispersion were prepared. Effect of ageing on the physical properties of the prepared 1 tablets was investigated.