On the release of drug from hard gelatin capsules

The effect of particle size and packing on the in vitro release of a water-insoluble hydrophobic drug from hard gelatin capsules has been related to the liquid permeability of powder beds of similar porosities. Drug release and permeability decrease with a decrease in particle size and porosity of the powder bed. A simple moist granulation process transforms a non-permeable powder bed, which allows low drug release, into one with high permeability and high drug release.