Simple and Sensitive Spectrophotometric Assays for the Determination of Terbinafine HCL Antifungal Drug in Pharmaceuticals

Objective: Two highly sensitive, accurate, inexpensive, and simple spectrophotometric assays were developed and validated for the determination of an anti-fungal drug, Terbinafine HCl (TBH), in pure drug and tablets using potassium permanganate (PP) and disodium 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-yl)quinoline-6,8-disulfonate (DSOQ). Material and Method: In the present study, Sebifin and Terbiforce 250 mg tablets were used as pharmaceuticals, potassium permanganate KMnO4 and disodium 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-yl)quinoline-6,8-disulfonate in water were used as reagents, and DR 3900 spectrophotometer equipped with 1cm matched quartz cells was used for absorbance measurements. Result and Discussion: The amount of terbinafine hydrochloride reacting with permanganate and disodium 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-yl)quinoline-6,8-disulfonate in an acidic medium has been determined. The colored reaction products in both cases were measured at the maximum absorptions of 540 nm and 440 nm, respectively. The absorbance measured in each assay as a function of TBH concentration was related to TBH concentrations. Different experimental and variable conditions of assays were done carefully, accurately studied, and optimized. The validation of two assays also was done by following the current guidelines of the International Conference on Harmonization (ICH). Beer’s law for the two methods is obeyed over the concentration ranges 1-15 µg/ml (Correlation coefficient = 0.9983) and 1-18 µg/ml (Correlation coefficient = 0.9989) for methods PP and DSOQ, respectively. Molar absorptivity, limits of detection, and quantification (LOD LOQ) values were (1.38×104 l/ mol cm, 0.92 2.78 µg/ml) for PP assay, and (1.73×104 l/ mol cm, 0.09 0.27 µg/ml) for DSOQ assay, respectively. The two assays were successfully applied for the determination of TBH in commercial tablets with reliable and satisfactory results, and hence the proposed assays can be applied in pharmaceutical laboratories of quality control.