Hard gelatine capsules: DEM supported experimental study of particle arrangement effect on properties and vibrational transport behaviour

Abstract

Hard gelatine capsules remain a relevant dosage form for today's pharmaceutical manufacturing. A wide range of colour and print options supports marketing, brand image and patient loyalty. However, the filling of these cap-sules with various modern dosage forms and combinations thereof may affect their further processing. Therefore, a detailed study was carried out to assess the effect of mechanical-physical properties on the behaviour of differ-ently filled hard gelatine capsules. Capsules filled with powder, free or fixed particles presenting drug microforms and also hard gelatine capsules themselves were evaluated. Basic mechanical-physical characterisation was per -formed on all samples. Furthermore, their transport on the vibrating conveyor was assessed and simulated using DEM. The results showed a significant influence mainly by the degree of capsule imbalance, i.e., the arrangement of particles in the capsule. It was found that the hard gelatine capsules showed an average of 15.6 degrees lower values for the effective angle of internal friction compared to the powdered vitamin mixture, and in parallel, an average of 14.7 degrees lower values for the static angle of repose were also recorded. The results of the experiments on the vi-brating conveyor at a frequency setting of 15 Hz showed three times longer transport time for the vitamin mix-ture compared to the capsules. Increasing the frequency evened out these differences.