Abstract
This study represents the first report on the development of a novel spectrophotometric method for determination of cinacalcet hydrochloride (CIN) in its tablet dosage forms. Studies were carried out to investigate the reaction between CIN and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 8.5), an orange red-colored product exhibiting maximum absorption peak (λmax) at 490 nm was produced. The stoichiometry and kinetic of the reaction were investigated and the reaction mechanism was postulated. This color-developing reaction was employed in the development of a simple and rapid visible-spectrophotometric method for determination of CIN in its tablets. Under the optimized reaction conditions, Beer's law correlating the absorbance with CIN concentration was obeyed in the range of 3 - 100 μg/ml with good correlation coefficient (0.9993). The molar absorptivity (ε) was 4.2 × 105 l/mol/cm. The limits of detection and quantification were 1.9 and 5.7 μg/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations (RSD) did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of CIN in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 100.80 - 102.23 ± 1.27 - 1.62%. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories.
Highlights
Cinacalcet hydrochloride (CIN); N-[1-(R)-(-)-(1-naphthyl) ethyl]-3-[3-(trifluoromethyl) phenyl]-1-aminopropane HCl is a selective calcimimetic agent, which acts on a calciumsensing receptor of the parathyroid gland
CIN is effective in clinical setting and it has been approved for the treatment of secondary hyperthyroidism in patients with chronic kidney disease placed on dialysis [3], and for the treatment of elevated calcium levels in patients with parathyroid carcinoma [4]
Because of the blue shifted lmax of CIN, its determination in the pharmaceutical formulations based on the direct measurement of its absorption for ultraviolet light is susceptible to potential interferences from the coextracted excipients
Summary
Cinacalcet hydrochloride (CIN); N-[1-(R)-(-)-(1-naphthyl) ethyl]-3-[3-(trifluoromethyl) phenyl]-1-aminopropane HCl is a selective calcimimetic agent, which acts on a calciumsensing receptor of the parathyroid gland. Preparation of Solutions Standard CIN Solution An accurately weighed amount (50 mg) of CIN was quantitatively transferred into a 25-ml calibrated flask, dissolved in 20 ml distilled water, completed to volume with the same solvent to obtain a stock solution of 2 mg/ml. The filtered solution was diluted quantitatively with distilled water to obtain suitable concentrations for the analysis by the proposed spectrophotometric method. Series of 10-ml portions of the master solutions of CIN and NQS were made up comprising different complementary proportions (0:10, 1:9,..., 9:1, 10:0, inclusive) in 10-ml calibrated flasks containing 0.5 ml of tris buffer solution (pH 8.5). The logarithms of the obtained absorbances for the reaction of CIN with NQS were plotted as a function of the logarithms of the concentrations of the reagent and CIN in the first and second sets of experiments.
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