Development and Validation of HPLC Assay of a New Molecule, 6-methyl-3-phenethyl-3, 4-dihydro-1H-quinazoline-2-thione from Solid Lipid Nanoparticles and its Topical Formulations

Abstract

A rapid and sensitive high performance liquid chromatography (HPLC) method has been developed and validated for the quantitative determination of a new molecule, 6-methyl-3-phenethyl-3,4-dihydro-1H-quinazoline-2-thione from solid lipid nanoparticles and its topical formulations according to the loading amount. This new molecule is going to be developed as skin whitening agents with topical formulations such as creams, ointments, and gels. The analyses were carried out on a Kromasil 60 CN column (10 µm, 250 mm × 4.6 mm) using a mobile phase composed of water-acetonitrile-diethylamine (600:400:4,v/v) adjusted to pH3.5 with phosphoric acid, following at a flow rate of 2 mL/min. Methyl benzoate was used as the internal standard (IS). The method offers excellent linearity with regression coefficient r2 > 0.998, good repeatability, reproducibility, and relatively short analysis time (20 min). The sample preparation was carried out by a simple extraction of a new molecule with mobile phase, subsequently sonicated for 10 min. The above HPLC conditions resolved the diluted new molecule, pharmaceutical excipients, and potential degradants within 20 min, with a new molecule eluting at about 12.7 min and IS at 4.2 min. System suitability parameters and validation parameters including method precision, accuracy, and linearity were setup. The relative standard deviations (RSD) of precisions in the solid lipid nanoparticles consisting of 0.25 g of a new molecule were satisfactory to 0.48%. The detects of quantification (LOD) and the limits of quantification (LOQ) for the new molecule in topical formulations, including 0.25 g of solid lipid nanoparticles, were 2.52 µg/mL and 5.37 µg/mL and the mean recovery value was 100.67% with a RSD less than 0.78%. The proposed procedures were successfully applied for the determination of the new molecule in solid lipid nanoparticles and its topical formulations and control during stability studies.