Abstract

A novel, reproducible, precise, accurate and dependable high-performance thin-layer chromatographic technique was developed and authenticated as per International Conference on Harmonization guiding principle for quantitative evaluation of forskolin as a bulk drug and in a nanosuspension. Chromatographic plates 60 F-254 pre-coated with silica gel and a solvent system of ethyl acetate:hexane:formic acid (7:2.9:0.1 v/v) was used for the development of the plates. Densitometric scanning of the developed plates in the reflectance mode at 555 nm using a Camag TLC scanner after exposing the plates to anisaldehyde-sulphuric acid reagent, gave a compact spot for forskolin (R_f=0.46±0.012). In accordance to the ICH guidelines, the method was validated for linearity, precision (intra- and inter-day), limit of quantification and limit of detection, robustness and accuracy. Good linear relationship was observed for the calibration plots with linear range from 100-1000 ng/spot and a coefficient of correlation r²=0.994. Limit of detection and limit of quantification were found to be 10.83 and 36.12 ng/spot, respectively. The method appeared to be well suited for determining forskolin content in the developed nanoformulation. Forskolin was found to be susceptible to acid and alkali hydrolysis, oxidation, photochemical degradation with UV and sunlight. Statistical analysis confirmed that the process developed is precise, repeatable, accurate, and suitable for the analysis of forskolin in a formulation and could be used also for analysis of forskolin in plasma and other biological fluids. The ability of the developed method to separate the drug from its degradation products effectively confirmed that it could be a stability indicating method.