Further studies on the effect of additives on the release of drug from hard gelatin capsules

Abstract

An experiment based on a 33 design has been undertaken to establish the effect on drug release from capsules produced by adding lactose (0, 10 and 50%), magnesium stearate (0, 1 and 5%), and sodium lauryl sulphate (0, 1 and 10%) to a 76–105μm particle size fraction of ethinamate filled into capsules at a high and low packing density. Statistical analysis of the results indicated the presence of 2nd order interaction at all time intervals and for both sets of capsule fill weights. This signifies that the effect produced by each additive is dependent on the presence and the level of the other two additives. The interaction limits the conclusions that can be drawn about the main factors of diluent, lubricant and wetting agent, but the indications are that (a) 10% diluent reduces drug release, whereas 50% produces enhanced release; (b) the presence of 1% sodium lauryl sulphate is sufficient to enhance drug release; (c) the additive effects are independent of the capsule packing density.