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Four spectrophotometric approaches had been established and optimized for the simultaneous estimation of two anti-diabetic drugs; linagliptin (LIN) and empagliflozin (EMP) in their bulk and tablet dosage form. LIN concentration could be first determined from the zero order spectra at its λ max (293 nm) without interference from EMP as at this wavelength EMP showed zero absorbance. The LIN and EMP zero order absorption spectra displayed considerable overlap which hindered the direct determination of EMP. Thus, four indirect spectrophotometric approaches were established and optimized for the determination and quantification of EMP concentrations in presence of LIN. Method (I) was ratio difference method (RD) which depended on the determination of difference amplitudes in the ratio spectra (ΔP) at 236 nm and 227 nm; ΔP (236-227) was directly proportional to EMP concentration. Method (II) was ratio derivative method ( 1 DD) based on the measuring of the amplitude of first derivative of ratio spectra at 243 nm which was directly proportional to EMP concentration. For determination of EMP concentration using both method (I) and (II); LIN 7 µg/mL was used as the divisor. Method (III) was area under curve method (AUC) which depended on the measurement of area confined between 220 and 230 nm and 273-290 nm. Method (IV) was dual wavelength method (DWL) which based on measurement of absorbance difference (ΔA) in zero order spectra between 239.8 and 282.6 nm which was directly proportional to EMP concentration. The four developed methods were optimized and entirely validated regarding to ICH guidelines. The proposed spectrophotometric approaches were used for the quantification of LIN and EMP simultaneously in their tablet dosage form. F-test and t-test were applied for statistical comparison between the results obtained by the proposed approaches and that obtained by the reported method. There was no significant difference concerning to precision and accuracy., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

New simple sensitive and reliable spectrofluorimetric approach was established for the determination of the antidiabetic drug; Alogliptin (ALG) in its pure and tablet forms. The developed approach is depended on the suppressive action of ALG on the eosin Y native fluorescence. The quenching action of ALG on the eosin Y native fluorescence was measured at acidic medium pH: 3.5, emission wavelength 541 nm (λ ex. 260 nm). The relative fluorescence intensity (RFI) was measured, and it was directly proportional to ALG concentration in the concentration range of (15-110) μg/mL. The developed and optimized approach was entirely validated regarding to ICH guidelines. The developed method application was successfully extended for ALG content uniformity test (CU). The distribution fraction (DF), rate constants (K), and free energy changes (ΔG°) were calculated. The results obtained were compared to that of the published spectrophotometric one., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Allergic rhinitis and urticaria are extremely prevalent among all age groups. From the clinical experience, usually, an essential second-generation non-sedating H 1 -antihistaminic drug, such as bilastine is given to relieve allergic symptoms. Bilastine is preferred to be used instead of oral corticosteroids and first -generation sedating H 1 -antihistaminics to avoid their side effects. A highly sensitive and simple spectrofluorometric method was developed and validated for the determination of bilastine in its dosage forms and biological fluids. The quantum yield was calculated and was found to be as high as 0.48. Aqueous water solution of bilastine gives high native fluorescence emission at 298 nm after excitation at 272 nm. A rectilinear calibration plot was obtained over the concentration range of 1.0-50.0 ng mL -1 . The limits of quantitation and detection were 1.0 and 0.33 ng mL -1 , respectively. The parameters influencing its spectrofluorimetric behavior, viz, type of solvent, pH and organized media were studied. The proposed method was successfully applied for the determination of the drug in pharmaceutical dosage form and the results obtained were in good agreement with those of given by reported method. The high sensitivity of the proposed method enabled the estimation of the drug in biological matrices, including human plasma and urine samples after simple protein precipitation, and the results obtained were satisfactory., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Nine simple, cost-effective, and sensitive spectrophotometric methods were developed to simultaneously assay benoxinate HCl and fluorescein sodium in their co-formulated eye drops without barring common excipients. A direct UV spectrophotometric method (method I) was developed for their FLU assay at 481 nm over the concentration range of 0.6-10.0 μg mL -1 . Meanwhile, BEN was assayed over the concentration range of 1.0-25.0 μg mL -1 by different UV based methods, namely, conventional dual-wavelength method (DW) (method II), first derivative 1 D spectrophotometry (method III), second derivative 2 D spectrophotometry (method IV), ratio spectra difference spectrophotometry (method V), the first derivative of ratio spectra (method VI), ratio subtraction method (method VII), isosbestic point method (ISP) (method VIII) and absorption factor method (method IX). The performance of the proposed methods was assessed relying on the correlation coefficients, relative standard deviations, and limits of detection and quantitation. The variance ratio F-test and Student t-test showed no significant differences between the obtained results of the developed methods and those of reference methods. The proposed methods were also applied to determine studied drugs in commercial eye drops and aqueous humor., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)