Background and importance Pharmaceutical compounding is an integral part of the services provided by pharmacies for the specific needs of patients. For these pharmaceutical preparations the requirements of the European Pharmacopoeia (EP) regarding the microbiological quality apply, namely that in the manufacture and packaging, as well as during storage and distribution, suitable measures have to be taken to ensure their microbial quality.

Aim and objectives This study evaluated the microbiological quality of non-sterile pharmaceutical preparations of the hospital pharmacy of a University Hospital. A risk-based approach was chosen for the identification of the most microbiologically susceptible non-sterile pharmaceutical preparations.

Material and methods A risk matrix of all 42 non-sterile pharmaceutical stock preparations was created, taking into account the characteristics of the active substance and the formulation, as well as the manufacturing process risk of the individual pharmaceutical dose form. To confirm the microbiological quality, tests were conducted using membrane filtration and the surface-spread method according to EP 2.6.12. Suitability tests were carried out in the presence and absence of the selected products with five American Type Culture Collection (ATCC) test strains.

Results The risk evaluation resulted in seven non-sterile pharmaceuticals of the different pharmaceutical dosage forms with a high microbial risk: calcium glycerophosphate capsules, clobetasol adhesive gel, EEG gel, misoprostol capsules, opium tincture, propranolol solution and sucrose solution, to be tested according to EP 2.6.12. The permitted recovery rate of the test strains of 50% to 200% was fulfilled for all tested products and the chosen method was suitable for the specific products. The seven worst-case products were tested in duplicate and only the opium tincture and the EEG gel showed a microbial growth of one and three colony-forming units (CFU), respectively. These results are fully within the requirements of the pharmacopoeia.

Conclusion and relevance This study demonstrates that non-sterile production of different dosage forms (including packaging and storage) in a hospital pharmacy can guarantee the microbiological quality of pharmaceutical preparations. Only neglectable microbiological growth even of the pharmaceutical preparations with the greatest risk was observed, so that overall the requirements of the pharmacopoeia are fulfilled.

Conflict of interest No conflict of interest