[The determination and interpretation of in-vitro dissolution behavior of pharmaceutical substances. 1. Powders, mixtures and granules].

Dissolution testing of hydrophobic powders with the flow-through method but without powder preparation doesn't guarantee accurate, reproducible and reasonable results in aqueous test media of high surface tension. Mixing drug powders with seasand or using fast desintegrating granules enables an exact determination and realistic valuation of the dissolution behaviour. Addition of surfactants generally accelerates the dissolution rate but problems as drug agglomeration and flotation remain.