In-vitro dissolution properties of indomethacin extended-release capsules

In-vitro dissolution properties of indomethacin extended-release capsules, from samples available on the Japanese market, have been investigated using a continuous flow, column-type dissolution apparatus and the results compared with those obtained by the paddle and the rotating basket methods. A plot of the percent of drug dissolved against the square root of time gave a straight line with the flow-through method but not with the paddle or the rotating basket methods. The results suggest an advantage of the flow-through method over the other two methods when extended-release products are tested by in-vitro dissolution.