Background and importance Deblistering of medication is a critical step in unit dose blister production. In our setting, large quantities of push-through packs are processed by manually operated deblistering machines. Visibly damaged drugs are removed. However, it has not been investigated whether mechanical stress by deblistering machines can cause minimal, hardly identifiable damage with negative effects on functional coating.

Aim and objectives The influence of machine-aided versus manual deblistering on drugs with modified release was studied to rule out negative effects on functionality of coating. Purposely damaged tablets with tiny superficial defects served as positive controls. Enteric coating and extended release were investigated in tablets chosen for their high deblistering volume and critical active agent, respectively.

Material and methods Thrombo ASS 100 mg (acetylsalicylic acid; enteric coating) and Quilonorm retard 450 mg (lithium carbonate; retardation of release) were deblistered (A) manually, (B) with deblistering machines and (C) manually and then minimally damaged on the surface with a pointed item. Ten tablets of each group were analysed in two ways. (1) Disintegration testing was performed based on the methods of the European Pharmacopoeia. (2) Tablets were immersed into a methylene blue dye bath to visualise intactness of coating as well as damaged areas.

Results Manually and machine deblistered Thrombo ASS tablets met the required 2 hours of acid stage duration in 0.1 N HCl. The minimally damaged fraction started to disintegrate within seconds. When transferred to neutral buffer solution, manually and machine deblistered tablets showed identical disintegration behaviour. All three groups of Quilonorm retard tablets showed acid stability and disintegrated the same way in a pH-neutral environment. Cavities and grooves were visible on damaged tablets immersed into the dye bath. Tablets deblistered by hand and machine showed identical, even dying of their surfaces.

Conclusion and relevance Although minimal damage can lead to a loss of coating functionality, machine-aided deblistering showed no negative effects on coated tablets. Neither differences in disintegration tests nor in the dye bath were detected compared with manually deblistered tablets. These results were examined during a good manufacturing practice (GMP) inspection by the Austrian authority, support machine qualification and the validation of this important step in the unit dose blister process and may therefore be of interest for other production sites.

Conflict of interest No conflict of interest