Simultaneous Determination of Carbinoxamine, Pholcodine, and Ephedrine in Antitussive Preparation by High-Performance Liquid Chromatography and Thin-Layer Chromatography-Densitometry

Simple, accurate, precise, sensitive, and validated high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC)-densitometric methods were developed for the simultaneous determination of carbinoxamine (CAR), pholcodine (PHL), and ephedrine (EPH) in antitussive syrup. In method A, reversed-phase (RP)-HPLC analysis was performed on an Inertsil CN-3 column (250 mm × 4.6 mm, 5 µm), using a mobile phase consisting of acetonitrile-distilled water (pH 3.5) using orthophosphoric acid in the ratio 70:30 (v/v) and flow rate of 1.5 mL min−1. Quantitation was achieved with ultraviolet (UV) detection at 220 nm. In method B, TLC analysis was carried out on an aluminum-backed sheet of silica gel 60 F254 layer using chloroform-propanol-ammonia (6:4:0.1, v/v) as the mobile. Quantification was carried out with UV detection at 245 nm. The validation of the proposed methods was applied according to the International Conference on Harmonization (ICH) guidelines. The suggested methods were successfully applied for the determination of the cited drugs in bulk powder and commercial dosage form.