Development and Validation of the Sterility Test for a New 1mg/mL Ropivacaine Preparation

Introduction
Our unit received a request for the production of a new 1mg/mL ropivacaine hospital preparation in bags. This preparation aims to replace the use of the commercial 2mg/mL ropivacaine formulation, administered epidurally for pain management in major visceral and urological surgery which has significant hemodynamic effects on patients. A sterility test is required for sterile injectable preparation.

Objective
To develop and validate the membrane filtration sterility test method for a new 1mg/mL ropivacaine preparation.

Materials and Methods
The membrane filtration method was carried out according to the European Pharmacopoeia 11th edition (2.6.1) using a Steritest^® Equinox pump (Merck-Millipore) and canisters equipped with a 0.45µm cellulose ester membrane (Merck-Millipore). A fertility test (positive control) and a sterility test were conducted. The microbial strains recommended by the European Pharmacopoeia were tested: Staphylococcus aureus, Clostridium sporogenes, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, and Aspergillus brasiliensis. The aliquots of these six strains were prepared from BioBall^® Multi-shot 550 (Biomérieux) and introduced into the 100mL bags before filtration. A negative control was performed for each medium. After filtration, the canisters were incubated at 30-35°C for the thioglycolate medium and at 20-25°C for the casein and soybean hydrolysate medium. The applicability test was performed three times by three different operators.

Results
Microbial growth of the six strains, comparable to the positive controls, was observed as early as day 3 for all three operators. The microbial strain identification results showed a monomorphic growth of each pathogen. The negative controls remained clear, indicating the absence of microbial contamination. Fertility and sterility tests were compliant.

Discussion/Conclusion
The applicability test validates the membrane filtration sterility test method for this preparation. The absence of an inhibitory effect of 1mg/mL ropivacaine on pathogen growth has been demonstrated. This method will be routinely used as part of the microbiological control of this preparation.

See the poster