Development of a reversed‐phase high‐performance liquid chromatographic method for the determination of propranolol in different skin layers

The aim of this work was to develop and validate an analytical method using HPLC for the determination of propranolol in the different layers of the skin to be used in kinetic studies of skin permeation. The development of the method was based on the suitability of the chromatogram, and the validation followed the international health regulation for bioanalytical methods. In addition, the method was tested in an in vitro permeation assay using porcine skin. The drug was determined using an RP‐C18 column at 30°C, a mobile phase comprising acidic aqueous phase:acetonitrile (75:25 v/v), at a flow rate of 1.0 mL min−1, and UV detection at 290 nm. The method was demonstrated to be selective against skin contaminants, linear in a wide range of concentrations (3–20 μg mL−1), sensitive enough to quantify less than 0.1% of the drug dosage in skin matrices, and precise regardless of analysis variations such as day of analysis, analyst, or equipment. In addition, the method presented a high drug extraction capacity greater than 90% for all skin layers (stratum corneum, hair follicle, and remaining skin). Finally, the method was successfully tested in skin permeation assays, proving its value in the development of topical formulations containing propranolol.