Benzyl Alcohol is a Great Disinfectant

By: SV-1

Development of a Multidose Formulation for a Humanized Monoclonal Antibody Using Experimental Design Techniques

"The efficacy of the preservative against various microorganisms was measured using a modified USP/EP PET (referred to as preservative screening test in this document). Tests were conducted at Microconsult Inc (Dallas, TX). In the procedure, formulations were tested against the following microorganisms: Escherichia coli, Staphylococcus aureus, Pseu***onas aeruginosa, Candida albicans, and Aspergillus niger. The 3 bacterial strains were inoculated together at a total concentration of ~105 cfu/mL, as were the 2 fungi. Samples were incubated for 7 days at room temperature (25°C), and the total bacterial and fungal counts were measured using a colony counter. The log reduction (LR) values for the bacterial and fungal counts were calculated as log (initial count/final count)."

"Results of the preservative screening tests showed that the formulations containing 0.75% and 0.5% benzyl alcohol are potential candidates to meet the USP/EP criteria (Table 4). Both formulations demonstrated a complete kill of the tested bacterial and fungal species after 7 days. For all other samples, either the total bacterial count after 7 days was too numerous to count, or no effective reduction in the bacterial count was observed."

"benzyl alcohol caused significant aggregation at high concentrations (≥1.0%); however, it was the most effective preservative in maintaining antimicrobial efficacy against bacteria and fungi."

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Antimicrobial effectivenessTo determine the optimal composition of a storage solutionwith respect to antimicrobial effectiveness, a comparativestudy including different concentrations of benzyl alcoholin water or in buffers with pH 5.5 or 6.4 was performed.Test organisms were chosen according to USP 51 [1], andthe concentration of microorganisms in the solutions wasmeasured after 24 h and after 7 days.No major differences between the tested conditions havebeen observed. 1% benzyl alcohol fulfills USP 51 criteria but isslightly less effective than 20% ethanol. Therefore, 2% benzylalcohol was chosen for further studies. At this concentration,buffering or pH does not appear to affect the result.Full USP 51 tests were performed for a representative choiceof chromatography media (see Table 2). All tested mediacompleted this test successfully. After 7, 14, and 28 days, nocolony-forming units (CFU) were detected, demonstratinga complete inactivation of biological activity. The resultobtained for Q Sepharose™ Fast Flow is representative for alltested media (Table 1).For some chromatography media, 0.2 M sodium acetate, pH ~ 8,is added to the storage buffer to stabilize the ligand. Theantimicrobial effectiveness has sometimes been reported tobe lower at pH values > 7 and USP 51 tests were thereforeperformed on a number of chromatography media thatrequire buffering with 0.2 M sodium acetate (Table 2).After seven days, no microbial growth was detected. In fact,no tendency for less antimicrobial effectiveness can be seenin storage solutions above pH 7.To ensure that the antimicrobial effect of the 2% benzylalcohol solution would last for the entire shelf life of achromatography medium, a sample of benzyl alcohol thathad been used for storage for a four year period was tested.The result was the same as for a newly prepared solution,confirming that the anti-microbial effect lasts for the entirestorage period.

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