An innovative RP-HPLC strategy for dual-drug analysis: simultaneous estimation of selegiline and biochanin A in bulk...

This study aimed to develop and validate a rapid, accurate, and robust RP-HPLC method for the simultaneous quantification of Selegiline (SEL) and Biochanin A (BCA) in bulk and in self-nanoemulsifying drug delivery system (SNEDDS). Developing a validated analytical method for the novel SEL-BCA combination is important for ensuring precise quantification of the combination's potential applicability in Parkinson's disease (PD) management.

Chromatographic separation was performed using an Agilent 1220 Infinity II HPLC system equipped with a 5TC-C18(2) column (250 × 4.6 mm, 5 µm) and a variable wavelength detector (VWD). An isocratic mode with mobile phase of acetonitrile (ACN) and water containing 0.1% o-phosphoric acid (50:50 v/v) was used at a flow rate of 1 mL min^-1, with detection at isosbestic wavelength of 208 nm. Validation followed ICH Q2(R1) guidelines. SEL-BCA SNEDDS was formulated and characterized for particle size and PDI, and the validated method was applied to quantify in vitro drug release and % drug assay.

The method displayed excellent linearity over the 0.4-50 µg mL^-1 concentration range, with correlation coefficients of 0.9997 for SEL and 0.9995 for BCA. System suitability parameters, including tailing factor < 1.5, resolution > 2, and theoretical plates > 2000, were satisfactory. The method remained robust despite small variations in flow rate, column temperature, injection volume, wavelength, and mobile phase composition. The developed SNEDDS presented a particle size of 120.3 nm and a PDI of 0.1925.

A simple, sensitive, and robust RP-HPLC method was successfully developed and validated for the concurrent estimation of SEL and BCA in bulk drug and SNEDDS.