抄録
The Simple Suspension Method is used for dissolving tablets or capsules in hot water to make a pharmaceutical suspension that is administered via a gastrostomy tube. This method does not require any special devices; thus, it is used by many health-care facilities in Japan. However, information on the solubility of drugs administered using this method is very limited. This study aims at collecting such data. For this purpose, tests were conducted for evaluating the solubility of three poorly water-soluble drugs-phenytoin, pranlukast and ibuprofen-and for comparing proprietary drugs and generic drugs in terms of solubility. A phenytoin tablet (100 mg), a pranlukast hydrate capsule and tablet (112.5 mg), and an ibuprofen tablet and granules (100 mg) were respectively dissolved in hot water (55°C, 20 mL) to make suspensions, and the concentration of each suspension was measured at 5, 10 and 180 minutes. The temperature of each suspension decreased over time. The concentration of phenytoin and pranlukast in the suspensions also decreased with time. Regarding the two types of phenytoin tablets used in the tests, the degree of dissolution at 5, 10 and 180 minutes after dissolution in water was roughly the same. The concentration of each phenytoin suspension was near the saturation level. Each of the pranlukast hydrate products used in the tests dissolved so well that the saturation solubility was exceeded in each suspension. The solubility of the proprietary pranlukast hydrate products was higher than that of the generic products. While the solubility of the ibuprofen granules decreased over time as did the phenytoin and pranlukast products, the solubility of the two types of ibuprofen tablets increased with time. These results indicate that the solubility of poorly water-soluble drugs depends on the changes over time in the temperature of their suspensions, and that generic products are different from proprietary products in solubility.
