One-pot reaction for determination of Asenapine maleate through facile complex formation with xanthine based dye: Application to content uniformity test

Asenapine maleate was approved by the FDA for the treatment of schizophrenia and mania or mixed episodes with bipolar I disorder. In the present article, two spectroscopic methods were developed and validated for the determination of asenapine. Both methods depend on association complex formation between xanthine based dye (eosin Y) and the cited drug in acetate buffer pH = 3.8. In the spectrophotometric method (method I), the absorbance of the formed complex was estimated at maximum wavelength of 545 nm and Beer's law was obeyed in the range of 1-12 μg mL^-1. The spectrofluorimetric method (method II) depends on measuring the quenching effect of the drug on the native fluorescence of eosin Y at 545 nm after excitation at 303 nm. The linearity range of method II was 0.4-3.2 μg mL^-1. The limits of detection were 0.24 and 0.08 μg mL^-1 for method I and II, respectively. The instructions of ICH were followed to fully validate the developed analytical procedures. The formation constant of the reaction was 3.93 × 10⁴ while its Gibb's free energy was -2.6 × 10⁴ J mol^-1. Finally, the methods were applied for the analysis of pharmaceutical tablets and for evaluation of their content uniformity.