2013 Volume 39 Issue 9 Pages 536-545
The dissolution behavior of drugs may alter depending of the type of semi-solidified material. We investigated differences in changes in the viscosity due to the characteristics of semi-solidified materials, and analyzed the dissolution behavior of drugs mixed with semi-solidified water at various viscosities and paddle rotation speeds.
Semi-solidified pure water by 7 semi-solidifiers was adjusted to about 8,000 mPa･s, and viscosity changes were measured using a cone-plate rotational viscometer. In addition, dissolution tests of drugs mixed with semi-solidified water were performed employing the paddle method. The sample viscosity was set at 2,000, 4,000, and 8,000 mPa･s. The rotation speed of the test was set at 50 rpm for samples with a viscosity of 2,000 and 4,000 mPa･s, and at 50 and 100 rpm for samples with a viscosity of 8,000 mPa･s.
Seven types of semi-solidified water showed a non-Newtonian flow and similar viscosity changes. On the dissolution test, drugs mixed with semi-solidified water containing starch as the main ingredient were rapidly eluted at all viscosities and paddle rotation speeds, and about 100％ dissolution was observed. The dissolution rate of drugs mixed with semi-solidified water containing polysaccharide thickener was low under all conditions, and the dissolution behavior was markedly different between samples with 4,000 and 8,000 mPa･s viscosity.
It is suggested that, for the semi-solidified material to elute a drug by mixing with semi-solidified water, a material containing starch as the main ingredient is the most appropriate because starch is eluted at a high rate within a short time and less influenced by the pH and viscosity.
