Chromatographic method for clobetasol propionate determination in hair follicles and in different skin layers.

Clobetasol propionate (CLO) is a potent steroid used for the treatment of several dermatological diseases. Recent studies suggest its additional use in alopecia topical treatment, generating a demand for novel formulations with specific delivery into hair follicles. Hence, a selective analytical method for drug quantification in follicular structures and skin layers is required. For this, a simple HPLC-UV method was developed. Quantification was performed using a RP-C column (4.6 mm × 15 cm, 5 μm), with a mixture of methanol-acetonitrile-water (50:15:35 v/v) as mobile phase, a flow rate of 1.2 mL/min, oven temperature of 30°C, injection volume of 50 μL and detection at 240 nm. The optimized conditions enabled a 12 min running with CLO elution at 10.1 min and resolution of 2.424 from skin matrix interferences. Validation was performed in accordance with International Conference on Harmonization guidelines and fulfilled the criteria of selectivity, linearity (0.5-15.0 μg/mL), robustness, precision, accuracy and limits of detection and quantification (0.02 and 0.07 μg/mL, respectively). The validated method was successfully applied for CLO quantification following in vitro skin permeation experiments and differential tape-stripping for hair follicle deposition determination, demonstrating its suitability.