The influence of agitation intensity, particle size and pH of dissolution fluid on the in-vitro release of drug from hard gelatin capsules.

ABSTRACT

The influence of agitation intensity on the in-vitro release of controlled particle size fractions of acetylsalicylic acid from hard gelatin capsules into buffered dissolution fluids has been investigated employing a dissolution technique. The value of T50 decreased as the stirring rate increased from 120 to 320 rev min-1 for all particle size fractions and pH values. A further increase in the stirring rate had a limited effect on the value of T50 and the changes were particle size dependent. The influence of the drug solubility, induced by changing the pH of the dissolution fluid, was decreased by increased agitation. When the capsules were filled at bulk densities above the maximum tapped bulk density, the value of T50 was increased, the extent of increase being greater the smaller the particle size of the drug. The kinetics of the solution process were influenced by agitation intensity and particle packing.