Stability-Indicating TLC Method for the Determination of Dutasteride in Pharmaceutical Dosage Forms

A simple, sensitive, selective, precise and stability-indicating thin-layer chromatographic method for determination of dutasteride both as a bulk drug and as pharmaceutical tablets was developed and validated as per the International Conference on Harmonization guidelines. The method employed thin-layer chromatography aluminium plates precoated with silica gel 60F₂₅₄ as the stationary phase and the mobile phase consisted of acetonitrile:methanol:dichloromethane in the ratio of 2.0:1.0:2.0, v/v/v. This solvent system was found to give compact spots for dutasteride (R _f value of 0.64 ± 0.02). Densitometric analysis of dutasteride was carried out in the absorbance mode at 244 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r = 0.9943 with respect to peak area in the concentration range of 100–600 ng per band. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 7.54 and 22.85 ng per band, respectively. Dutasteride was subjected to acid and alkali hydrolysis, oxidation, photo degradation, dry heat and wet heat treatment. The drug undergoes degradation under acidic, basic conditions, photolytic, oxidative and upon wet and dry heat treatment. The degraded products were well separated from the pure drug. The statistical analysis proves that the developed method for quantification of dutasteride as bulk drug and from pharmaceutical tablets is reproducible and selective. As the method could effectively separate the drug from its degradation products, it can be employed as stability-indicating.