Abstract
A new method for determining effective surface area of organic drug substances was developed by measureing the initial dissolution rate. The principle is based on comparison of the initial rate of the sample powder with those in the calibration curve predetermined with disks of the same powder which has a constant surface area. The procedure and apparatus used were similar to those previously reported. The method was tested with phenacetin and sulfanilamide powder, and its results were satisfactory to prove that the method is accurate, simple, and widely applicable. Also, goodness of the method that directly gives the effective surface area for dissolution was verified by comparing the results with those by conventional methods for particle size determination, such as sieve analysis and gas adsorption measurement.
