Powder filling into hard gelatine capsules on a tamp filling machine

A series of pharmaceutical excipient powders used in capsule formulations a s fillers have been filled into hard gelatine capsules on a Bosch GKF-400S tamp filling machine. These machines depend on pushing pins through a powde r bed so that a unit dose is transferred into a dosing disc. This dose is t hen ejected into the capsule body. The results indicate that the range of p owders that can be filled on this type of machine exceeds that applicable t o a dosator nozzle system. Filling problems due to powder flooding could be solved by increasing the powder bed height in the powder bowl. The fact th at such powders usually do not form a firm plug was not reflected in the co efficient of fill weight variation, and uniform filling could hence be achi eved without problems. The influence of the powder bed height on the capsul e fill weight increased with decreasing powder flow. The influence of the s etting of the tamping pins on the capsule fill weight was comparatively sma ll and further decreased with a decrease in powder flow. However, when a gr anulated product (Elcema G250(R)) was filled, the tamping pin setting was m ore important than the influence of the powder bed height on the capsule fi ll weight. For moderate flowing powders the coefficient of fill weight vari ation appeared to be nearly independent of powder bed height or tamping pin setting. However, the filling performance of powders with poor flow proper ties could be adjusted by optimising both machine settings. Very complex re lationships were found between the powder properties such as angle of inter nal flow, dynamic densification profile, Carr's compressibility index and p article size and shape, and the filling behaviour. (C) 1999 Elsevier Scienc e B.V. All rights reserved.