DEVELOPMENT AND VALIDATION OF STABILITY INDICATING HPTLC METHOD FOR DETERMINATION OF PHENOBARBITONE AS BULK DRUG AND IN PHARMACEUTICAL FORMULATION

A sensitive, selective, precise and stability indicating high performance thin layer chromatographic method of analysis of Phenobarbitone both as a bulk drug and in formulations was developed and validated in pharmaceutical dosage form. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of dichloromethane: ethyl acetate: glacial acetic acid (9.5:0.5:0.1 v/v/v/v). This system was found to give compact spots for Phenobarbitone (Rf value of 0.70). Phenobarbitone was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment also the degraded products were well separated from the pure drug. Densitometric analysis of Phenobarbitone was carried out in the absorbance mode at 244 nm. The linear regression data for the calibration plots showed good linear relationship with r²=/0.998/ in the concentration range of 200-/600 ng/band. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 5.82 and 14.60 ng per spot, respectively. The drug undergoes degradation under acidic, alkaline conditions, oxidation and dry heat treatment. Peaks of degraded product were resolved from the standard drug with significantly different Rf values. This indicates that the drug is susceptible to acid hydrolysis/alkaline hydrolysis, oxidation, dry heat degradation. Statistical analysis proves that the method is reproducible and selective for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one.