Coating process with gastric juice-resistant soln - - for gelatine capsules

Abstract

Abstract In prior art, the solubility of the gelatine envelope has been reduced by treatment with formaldehyde in a dry atmos. or by coating them with a thin film of resistant varnish. The results obtd. have not been reproducible and have not proved stable with time. In the new process, the hard gelatine capsules are coated with a film by spraying and simultaneous drying of a soln., which is resistant to gastric juices, while the capsules are in movement in a coating turbine, under reduced press. The coated capsules have a good appearance because of the uniformity and transparency of the film; good reproducibility is obtd. The spherical coating drum rotates around an oblique axis, and is charged with about 100,000 capsules and the lid is placed in position and partially sealed. With the drum in rotation the resistant soln. is introduced through a spray nozzle at the rate of 500 ml/min. Simultaneously a current of air at 60-80 degrees C is admitted; this dries the soln. in proportion as the latter coats the capsules.

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