The filling of molten and thixotropic formulations into hard gelatin capsules

Problems in the formulation and manufacture of conventional solid dose form products include the variation of fill weight and drug content, dissolution control of poorly water soluble drugs and dust generated during manufacture giving rise to cross contamination. We have examined the application of a liquid filling technique for the manufacture of hard gelatin capsules as a means of overcoming some of these. Filling materials are based on water-soluble hot melt polymers such as polyethylene glycol or water-dispersible thixotropic systems of pharmaceutical oils with thixotropic additives. A Zanasi LZ64 capsule filling machine was adapted to fill liquids using filling pump. No dust is generated during filling and 20 microgram doses of drug can be accurately filled without extensive processing. The formulations are simple and do not require specialist ingredients such as lubricants, binders, disintegrants and flow aids. The method of manufacture is reduced to a simple mixing and direct filling operation. The system may be applied to promote the dissolution of poorly water soluble drugs using solid solutions or solid dispersions. Slow release formulations are also available using suitable retard excipients.