The mucosal toxicity of different benzalkonium chloride analogues evaluated with an alternative test using slugs

Purpose. The objective of this study was to evaluate the mucosal toxicity of different benzalkonium chloride (BAC) analogues using slugs as the alternative test organism. Methods. The effect of different BAC analogues on the mucosal tissue of slugs was determined from the protein, lactate dehydrogenase, and alkaline phosphatase released from the foot mucosa after treatment. Additionally, mucus production and reduction in body weight of the slugs were measured. The eye irritation potency of the molecules was evaluated with the Bovine Corneal Opacity and Permeability (BCOP) assay. The antimicrobial activity of the different BAC analogues was also assessed. Results. All BAC analogues induced severe damage to the mucosal epithelium of the slugs, and the irritation increased with decreasing alkyl chain length: BAC-C16 < BAC-C14 < BAC-C12 similar to BAG-mix. A similar ranking was obtained with the BCOP assay for eye irritation. The relative order of activities among the three BAC analogues was the same, i.e., BAC-C14 greater than or equal to BAC-C16 > BAC-C12. The BAC-C14 exhibited higher activity than the BAG-mix. Conclusions. The toxicity and activity of BAG analogues depend on the alkyl chain length. The use of BAC-C14 as a conservative agent in pharmaceutical preparations instead of the BAG-mix should be considered.