Objective  To explore the necessity and methods of conducting microbial challenge test in the study of compatibility stability of injections, and provide reference for microbial challenge research of chemical drug injections.

Methods  By summarizing the regulations of various countries on the microbiological challenge test for compatibility stability, and taking methocarbamol injection as an example, a microbiological challenge test for compatibility stability was conducted, and the microbiological contamination status was analyzed to confirm the duration of clinical compatibility use. The 0.9% sodium chloride injection and 5% glucose injection were used as compatible solvents to prepare test solutions containing 4 mg/mL and 10 mg/mL of methocarbamol. Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Enterococcus faecalis, Candida albicans, and Aspergillus niger were inoculated, the number of surviving bacteria was measured at 4, 8, and 16 hours under storage conditions at 25 ℃, and the increase in logarithmic values (lg) relative to 0  h was calculated.

Results  The number of growing bacteria of all inoculated bacteria did not exceed 0.5lg at each time point.

Conclusion  The quality and safety risks of microbial contamination and proliferation are extremely low when methocarbamol injection is prepared, stored, and used according to the methods specified in the drug instructions. Conducting microbial challenge test on the compatibility stability of injections can provide scientific basis for the safe use of clinical compatibility.

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