RESUMO
BACKGROUND: Topical chlorhexidine gluconate (CHG) is used widely to reduce healthcare-associated infection. The optimal therapeutic dose for maximum efficacy and reduced toxicity is unclear, in part because of the lack of analytical methods to monitor CHG levels in skin. A novel method was developed to accurately measure CHG levels in skin after topical application with the goal of determining its pharmacokinetics in skin. METHODS: Ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to develop a validated assay for measuring CHG levels in skin cells collected by a non-invasive adhesive tape-stripping method. CHG levels in the skin stratum corneum of healthy adult volunteers were measured at 0.5, 4, 8, and 24 h after its application. RESULTS: Conditions for extraction of CHG were optimized and the assay was linear in the range 0.1-50 µg/mL (corresponding to 0.2-100 µg chlorhexidine/tape), with an intra-assay precision of 1.74-10.50 % and a relative error of ≤10 %. The inter-assay accuracy was in the range of 5.86-10.96 % with a relative error <9 %. CHG was stable on tapes stored at 4 °C and ambient temperature for 14 and 3 days, respectively. The recovery of CHG from the tape was quantitative and the matrix effect was determined as 2.1-14.8 %. CHG levels in healthy adult volunteer skin following topical application decreased rapidly over a 24 h period. CONCLUSIONS: A rapid, accurate and specific UHPLC-MS/MS method was developed for the measurement of CHG in the skin obtained by tape stripping that was linear over a large dynamic range. This assay afforded a simple and convenient non-invasive approach to monitor CHG levels in skin after topical application that can be applied to enable the optimal dose to prevent infection and minimize toxicity.
