Development, validation, and application of an RP-HPLC method for concurrent quantification of Minoxidil and Finasteride in a topical solution for hair regrowth

A topical solution comprising of Minoxidil (MXL) and Finasteride (FNS) for alopecia is formulated in the present work, which essentially contains a lipid-Lauroglycol FCC as a penetration enhancer. The objective of the proposed work was to develop a rapid, simple, and robust reverse phase high performance liquid chromatographic (RP-HPLC) method to determine MXL and FNS in the said formulation. Herein, the chromatographic conditions were optimized based on the theoretical principles of separation and physicochemical properties such as pKa and log P of both the Active Pharmaceutical Ingredients (APIs). The separation was accomplished on an Inertsil (R) ODS-3 C18 column (150 mm x 4.6 mm; 5 mu m of particle size) at 25 degrees C by using a mobile phase composed of 70:30 v/v ratio of Methanol and Milli-Q water along with 0.5% Triethylamine at pH 6.4 adjusted with Ortho Phosphoric Acid. Drug peaks showed a good resolution at 210 nm. The retention times for MXL and FNS were found to be 2.40 min and 6.39 min, respectively. The developed method was found to be linear (R-2 >= 0.998) in a concentration range of 5-100 mu g/mL for both the drugs. The method was validated according to the ICH guidelines Q2 (R1). The ability of the method to differentiate between the types formulations was demonstrated by the in vitro diffusion data performed using a highly sophisticated Strat-M (R) membrane. The cumulative amount of drug released (MXL and FNS) at the end of 24 hours was maximum for the topical formulation containing lipids prepared using isopropyl alcohol and propylene glycol as the base. (C) 2020 Academie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.