The filling of granules into hard gelatine capsules.

Four different granule size fractions of Sorbitol instant(R) were filled into hard gelatine capsules on a tamp filling (Bosch) and a dosator nozzle machine (Zanasi) to allow comparison of the filling principles. An acceptable filling performance was always achieved and was independent of the machine type employed. Tamp filling was found to be slightly better for the coarser granule size fractions, because it does not seem to rely on a firm plug formation. A direct relationship between the angle of internal flow (Varthalis and Pilpel, 1976) and the coefficient of fill weight variation was found for both systems. Using the dosator nozzle machine, the plug formed was always denser than the maximum bulk density, whereas on the tamp filling machine for smallest granule size the maximum plug density could not be achieved with the settings employed. The results suggest that in situations where a low plug density is an essential prerequisite for drug dissolution and bioavailability the tamp filling machine appears the more suitable filling principle. However, if a greater extent of compression is required in order to fill large dose drugs or to use a smaller capsule size, the dosator nozzle principle might work more successfully for granules.