PubMed · 239148
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D J Davies, D A Norton. 1975. Challenge tests for antimicrobial agents.. https://doi.org/10.1111/j.2042-7158.1975.tb09465.x
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Benzalkonium chloride (BAK) is a mixture of alkylbenzyldimethylammonium chlorides, which is commonly used as a bacteriostat. In this work, the three major homologues of BAK are quantitated in the over-the-counter eye care products Murine and Murine Plus using high-performance liquid chromatography (HPLC). The analytes are separated from various product excipients and concentrated by either solid-phase extraction onto Sep-Pak C18 cartridges or by an on-line column-switching technique using 1-cm reversed-phase precolumns. Absolute recoveries of BAK homologues by the solid-phase extraction technique ranged from 97.2 to 98.7% for standards and from 98.0 to 98.4% for samples. Absolute recovery of the BAK homologues by the column-switching technique was 101.3% for standards and ranged from 99.9 to 103.7% for samples. Relative recoveries were quantitative by both techniques. Assay precision (R.S.D. values) were +/- 2.2% to +/- 2.6% and +/- 0.4% to +/- 0.8% by solid-phase extraction and column-switching techniques, respectively. The method provides advantages of high sample throughput, excellent column life and automation.
The in vitro spermicidal activity of the commonly used surfactant spermicides and the antiseptic chlorhexidine, were quantified in a statistically reproducible manner, using donor semen and image capture analysis. The spermicidal activity was expressed as the ED50 under defined assay conditions. Using these parameters, the order of spermicidal activity was: Menfegol > nonoxynol-9 approximately benzalkonium chloride > sodium docusate > chlorhexidine. These differences were statistically significant.
PURPOSE: The question of whether artificial tears can lead to objective improvement of ocular surface disease in dry eyes is still unanswered. The aim of the current study is to assess the influence of artificial tears on corneal epithelial permeability of dry eyes. Furthermore, the effect of benzalkonium chloride, used as a preservative of artificial tears, on corneal epithelial permeability is investigated. METHODS: The corneal epithelial permeability of 40 dry eye patients (80 eyes) was measured by computerized objective fluorophotometry before and 6 weeks after treatment with artificial tears containing either polyvinyl pyrrolidone 2% without preservative (20 patients) or polyvinyl pyrrolidone 2% preserved with benzalkonium chloride 0.005% (20 patients). RESULTS: Before treatment, the epithelial permeability of the dry eye patients was found to be 2.7 times that of a control group. After treatment, the epithelial permeability of patients treated with unpreserved polyvinyl pyrrolidone 2% had decreased significantly (-37%; P less than 0.001), whereas patients who had been treated with polyvinyl pyrrolidone 2% preserved with benzalkonium chloride 0.005% showed an increase in epithelial permeability (+21%; P = 0.05%). CONCLUSION: These data suggest that, in dry eyes, treatment with unpreserved artificial tears may lead to an objective improvement in corneal surface disease. However, this effect may be counteracted by preservation of tear substitutes with benzalkonium chloride.