Effect of annealing of vials on glass-dust contamination of medical preparations

The rejection of vials of solutions due to entry by mechanical particles largely depends on the annealing of the vials. It is found that either glass particles separate from the vial surface or particles that precipitate or enter from outside attach themselves to the surface of the glass particles. The conditions for these processes to occur are considered. It is shown that rejects can be substantially reduced by a patented method of annealing the vials in cassettes instead of singly. Cassette annealing takes considerably more time (30-40 min) than annealing of single vials due to the complex heat transfer conditions between the hot zones of the furnace and the vials. A complex temperature distribution is attained along the height and throughout the volume of the vials (a considerable temperature gradient at high cooling rates (200-350 C/min)). At the same time, rejects can be considerably reduced with only short annealing in individual minifurnaces. 2 refs.