Abstract
Sustained release granules of bumetanide (BN) were prepared to obtain mild and sustained diuresis. BN was dispersed in combined matrixes of ethylcellulose (EC) with hydroxypropylmethylcellulose phthalate (HPMCP), povidone (PVP) or cyclodextrins (CDs). Release of BN from these preparations was evaluated by the JP XIII dissolution test in JP disintegration media No. 1 (pH 1.2) and No. 2 (pH 6.8) at 37°C. The interaction of BN with CDs in buffer solutions with different pHs was also investigated, and BN from the preparation with the component of BN : γ-CD : EC=1 : 4 : 2 (weight ratio) showed the most favorable sustained release pattern. The apparent stability constant of the γ-CD system on the BN solubility was greater than those of the α- or β-CD systems. Crystalline BN was not observed in this system in studies using powder X-ray diffraction spectra and a differential scanning calorimeter.
