Physical stability and resistance to peroxidation of a range of liquid-fill hard gelatin capsule products on extreme long-term storage

Abstract

Background: The industrial take-up of liquid-fill hard capsule technology is limited in part by lack of published long-term physical and chemical stability data which demonstrate the robustness of the system.Objective: To assess the effects of extreme long-term storage on liquid-fill capsule product quality and integrity, with respect to both the capsules per se and a standard blister-pack type (foil–film blister).Materials and methods: Fourteen sets of stored peroxidation-sensitive liquid-fill hard gelatin capsule product samples, originating ~20 years from the current study, were examined with respect to physical and selected chemical properties, together with microbiological evaluation.Results and discussion: All sets retained physical integrity of capsules and blister-packs. Capsules were free of leaks, gelatin cross-linking, and microbiological growth. Eight samples met a limit (anisidine value, 20) commonly used as an index of peroxidation for lipid-based products with shelf lives of 2–3 years. Foil–film blister-packs using PVC or PVC–PVdC as the thermoforming film were well-suited packaging components for the liquid-fill capsule format.Conclusion: The study confirms the long-term physical robustness of the liquid-fill hard capsule format, together with its manufacturing and banding processes. It also indicates that various peroxidation-sensitive products using the capsule format may be maintained satisfactorily over very prolonged storage periods.