Disintegrating Agents in Hard Gelatin Capsules. Part II: Swelling Efficiency

Abstract

The wicking and swelling properties of pure disintegrants were investigated from plugs prepared under conditions similar to those used in encapsulation of powder mixtures into hard gelatin capsules. Pure AcDiSol exhibited the greatest wicking and swelling action followed by Primojel, Polyplasdone-XL 10 and corn starch. The swelling properties of pure disintegrants correlated best with the swelling of formulation mixtures and the efficiency of these materials in enhancing the dissolution of hydrochlorothiazide. A change in the penetrating liquid from dilute acid to water altered the liquid uptake and swelling of AcDiSol and Primojel but not those of Polyplasdone-XL 10 and corn starch. The extent of swelling per unit volume of liquid absorbed, defined as the swelling efficiency, varied with time and type of disintegrant. The swelling efficiencies of pure AcDiSol and corn starch were unaffected by the nature of the penetrating liquid while Primojel and Polyplasdone-XL 10 exhibited greater efficiencies in water than in dilute acid. All disintegrants lost part of their efficiency when incorporated in capsule formulations, especially in very hydrophilic matrices. The rate of wicking action could be a limiting step in the rate and extent of swelling of a disintegrant and hence hinder its efficacy in hard gelatin capsules.