Combining derivative and synchronous approaches for simultaneous spectrofluorimetric determination of terbinafine and itraconazole

Fast concurrent determination of guaifenesin and pholcodine in formulations and spiked plasma using first derivative synchronous spectrofluorimetric approach

Guaifenesin and pholcodine are frequently co-formulated in certain dosage forms. A new fast first derivative synchronous spectrofluorometric method has been used for their simultaneous analysis in mixtures. Here, first derivative synchronous spectrofluorometry enabled the successful simultaneous estimation of guaifenesin at 283 nm and pholcodine at 275 nm using a wavelength difference (Δλ) of 40 nm. The method was fully validated following International Council of Harmonization guidelines. For guaifenesin and pholcodine, linearity was determined within the corresponding ranges of 0.05-0.30 and 0.10-6.0 μg/ml. The two drugs were effectively analyzed using the developed approach in their respective formulations, and the results showed good agreement with those attained using reference methods. The method demonstrated excellent sensitivity, with detection limits down to 0.007 and 0.030 μg/ml and quantitation limits of 0.020 and 0.010 μg/ml for guaifenesin and pholcodine, respectively. Therefore, the procedure was successful in determining these drugs simultaneously in vitro in spiked plasma samples and syrup dosage form. The developed methodology also offered an environmentally friendly advantage by utilizing water as the optimal diluting solvent throughout the whole work. Different greenness approaches were investigated to ensure the method's ecofriendly properties.

Fluorescence switchable sensor enabled by a calix[4]arene-Cu(II) complex system for selective determination of itraconazole in human serum and aqueous solution

A switchable fluorescence sensor based on a calix (Monapathi et al., 2021) [4]arene:Cu²⁺ complex (FLCX/Cu) has been developed for the detection of itraconazole (ITZ) with high sensitivity and specificity. For the development of the sensor, the selective complexation of a fluorescent calix (Monapathi et al., 2021) [4]arene derivative (FL-CX) with the Cu²⁺ ion causing fluorescence quenching was utilized. In addition, the sensor properties of the FLCX/Cu prepared were investigated. For this purpose, various substances (selected anions, cations, and drugs) with which ITZ can be found together were studied in an aqueous solution. Limit of detection (LOD) and limit of quantification (LOQ) values were determined in the range of 1.00-60.0 μg/L as 3.34 μg/L and 11.1 μg/L for ITZ, respectively. Moreover, the real sample analyses were performed in human serum and tablet form. Furthermore, the effect of some possible serum contents on sensor performance was also studied. All these studies confirmed the development of a simple, precise, accurate, reproducible, highly sensitive, and very stable fluorescence sensor.

First-order derivative synchronous spectrofluorimetric determination of two antihypertensive drugs, metolazone and valsartan, in pharmaceutical and biological matrices

In this study, a facile, rapid, and sensitive spectrofluorimetric method was evolved to analyse two antihypertensive drugs, namely, metolazone (MTZ) and valsartan (VST), in pharmaceutical and biological matrices. Both analytes exhibited intrinsic fluorescence activities which were significantly affected by environmental factors such as pH and solvent systems. However, simultaneous determination of MTZ and VST by conventional spectrofluorometry cannot be achieved simply because of the strong overlap between their fluorescence spectra. Thus, a combination of derivative and synchronous spectrofluorometry was conducted to overcome this dilemma. The proposed method relies on measurement of the first-order derivative of synchronous fluorescence intensity of the studied drugs at Δλ = 160 nm using 0.1 M acetic acid as the optimum solvent. The amplitudes of the first derivative synchronous fluorescence spectra of MTZ and VST were recorded at 236.0 nm (zero-crossing point of VST) and at 262.8 nm (zero-crossing point of MTZ) for simultaneous analysis of MTZ and VST, respectively. The fluorescent method was optimized efficiently to get the maximum selectivity and sensitivity by investigating different solvents, different buffer pHs, and different surfactants. The highest sensitivity and selectivity were achieved when 0.1 M acetic acid was used as a solvent. The method showed a linear concentration range of 10.0-100.0 ng mL^-1 and a limit of detection of <3.0 ng mL^-1 for each analyte. Statistical data analysis confirmed that no significant difference between the proposed spectrofluorometric method and the reference methods. The validity of the proposed spectrofluorometric method approved its suitability for quality control work. The proposed spectrofluorometric method was applied to assay the studied drugs in pharmaceutical dosage and in biological matrices with acceptable %recoveries and small RSD values.

Factorial design-assisted reversed phase-high performance liquid chromatography method for simultaneous determination of fluconazole, itraconazole and terbinafine

A 23 full factorial design model was used for the development of a new high performance liquid chromatography method with UV detection to estimate three antifungal drugs simultaneously. Fluconazole (FLU), itraconazole (ITR) and terbinafine (TRH) are co-administered for severe fungal infections. They have been determined using MOS-1 Hypersil C18 column and an isocratic eluent; methanol 95% and phosphate buffer 5% with 0.001% triethylamine. The pH was adjusted to 7, and the flow rate was 0.7 ml min-1. The three drugs were separated within less than 7 min at 210 nm. The developed method gave a linear response over 5-80 µg ml-1, 5-50 µg ml-1 and 1-50 µg ml-1 for FLU, ITR and TRH, respectively. It showed detection limits of 0.88, 0.29 and 0.20 µg ml-1 and quantification limits of 2.66, 0.88 and 0.60 µg ml-1 for the three drugs, respectively. The design of the experiment facilitated the optimization of different variables affecting the separation of the three drugs. The sensitivity of the designed method permitted the simultaneous estimation of ITR and TRH in spiked human plasma successfully.

Simultaneous estimation of troxerutin and calcium dobesilate in presence of the carcinogenic hydroquinone using green spectrofluorimetric method

In the present study, we conducted two facile and highly sensitive spectrofluorimetric approaches in order to quantify the vasoprotective agents; troxerutin (TROX) and calcium dobesilate (DOB) in the presence of hydroquinone (HQ) (as a highly toxic impurity and potential degradation product of DOB) in commercial formulations and human plasma. The first approach relies simply on using ethanol as an eco-friendly solvent for the estimation of DOB at 345 nm after being excited at 305 nm. The linearity was carefully investigated between DOB concentration and the relative fluorescence intensity in the range of 0.05-0.8 µg ml-1. Due to the high method simplicity and sensitivity, applying the first approach to quality control analysis and spiked human plasma samples with mean % recoveries 100.74 ± 3.71 adds another merit. The second approach involved rapid conventional fluorimetric estimation of ethanolic TROX solution in TROX/DOB combined dosage forms at 455/350 nm (emission/excitation) with a linear calibration chart covering the range of 0.1-1.2 µg ml-1. Moreover, the second approach involved a comprehensive study in a trial to solve the problem of superposition of DOB and HQ graph adopting the first derivative synchronous fluorimetric mechanism in ethanol at Δλ = 60 nm. Therefore, DOB was measured at 286 and 323 nm, while HQ could be quantitated at 301 nm. The Beer-Lambert Law has complied over the ranges of 0.1-1.0 and 0.02-0.4 µg ml-1 for DOB and HQ, respectively. Guidelines adopted by the International Council of Harmonization (ICH) were used to validate the target approaches. The developed methods are more convenient for routine quality control laboratory instead of the time-consuming and sophisticated reported techniques. Moreover, different aspects of evaluating the greenness of the proposed approaches were conducted to have a complete image of their environmental impact.