Determination of the extremolyte ectoine in plasma and a pharmacokinetic study in rats by a validated and BAGI-evaluated UPLC-MS/MS method.

Ectoine (ECT) has recently gained considerable interest in the healthcare sector due to its promising therapeutic benefits in a variety of human disorders. This research aimed to quantify the ECT plasma level in rats by creating and optimizing a sensitive and validated UPLC-MS/MS method. Prior to analysis, ECT extraction from the plasma samples was conducted via a protein precipitation procedure, using hydroxyectoine as an internal standard (IS). A 1.7 µm UPLC C8 column (100 mm × 2.1 mm) was selected for the chromatographic separation, using a gradient mobile phase consisting of acetonitrile and 0.05% formic acid. The electrospray ionization mass spectrometry (ESI-MS) was used to detect ECT in the positive ion mode. To determine the specific precursor and the product ions of ECT, multiple reaction monitoring (MRM) methods were carried out. The selected ion pair of ECT was 143.1 > 97 and 159.1 > 113.13 for the IS. The ECT's linearity range in rat plasma was found to be 1-1000 ng/mL, with a recovery rate of 96.48-97.37%. Consistent with FDA guidelines for bio-analytical method validation, the suggested method was validated. The method was efficiently employed to quantify the studied drug in spiked rat plasma with good accuracy and precision with no significant matrix effects. Furthermore, it was effectively used to investigate the pharmacokinetic behavior of ECT in rats after a single oral dose of 30 mg/kg.

Simultaneous determination of ofloxacin and bromfenac in combined dosage form using four different spectrophotometric methods.

Four simple, precise, accurate and validated spectrophotometric methods have been developed for the simultaneous determination of ofloxacin (OFL) and bromfenac sodium (BROM). Firstly, first and second derivative spectrophotometric methods (1D &2D) using a zero-crossing technique utilizing 309.3 and 257.5 nm for OFL and 290.7 and 246.5 nm for BROM as optimum working wavelengths in a binary mixture, respectively. Secondly, the first derivative ratio spectrophotometric method (1DD) in which peak amplitudes at 297.3 nm and 260.7 nm were chosen to simultaneously estimate OFL and BROM, respectively. Thirdly, dual wavelength (DW) method based on two selected wavelengths for each drug in such a way that the difference in absorbance is zero for the second one. At wavelengths 296.4, 348.4 nm BROM has equal absorbance values, therefore, these two wavelengths have been used to determine OFL. Similarly, 271.7 nm and 313.1 nm were selected to determine BROM in the combined formulation. Finally, the fourth method depends on ratio difference spectrophotometry (RDSM), in which the difference between amplitudes at 305.6 nm and 326.5 nm on the ratio spectrum of the mixture was directly proportional to the concentration of OFL; independent of the interfering components. Similarly, the difference between amplitudes at 265.1 nm and 275.4 nm on the ratio spectrum was used for the determination of BROM. The linearity was confirmed in the range of 4 - 18 µg/ml for OFL and BROM for the four methods. The proposed methods were used to determine both drugs in their laboratory prepared mixture and combined formulation with mean percentage recoveries of 99.41 ± 1.35% for OFL and 99.98 ± 1.30 % for BROM in method (A). In method (B), the mean percentage recoveries were 101.70 ± 1.61% for OFL and 101.90 ± 1.45% for BROM. In method (C) OFL was 99.57 ± 1.61% and 100.90 ± 1.62% for BROM. Finally, in method (D) the mean percentage recoveries were 99.37 ± 1.67% for OFL and 100.70 ± 1.59% for BROM. The developed methods were successfully employed for determination of OFL and BROM in laboratory prepared mixtures and combined formulation showing satisfactory recoveries. Methods validation was performed according to the International Conference on Harmonization (ICH) guidelines. The obtained results conformed to the accepted ranges of recovery, precision and repeatability.

The fabrication of an innovative extremely sensitive nano green carbon paste electrode amended with the nanocomposite CuO/Y for electrochemical quantification of amprolium in sheep meat and liver samples.

In this work, carbon paste electrode (CPE) and modified CPE with copper oxide or copper yttrium oxide were prepared for determining amprolium hydrochloride (AMP) by differential pulse voltammetry. AMP has an antiprotozoal activity for treating coccidiosis in poultry; their retaining- in sheep meat and livers- induces adversative effects for the customer. XRD pattern was employed to define the fabricated nanostructured materials; the elemental composition of the nanocomposite was examined using EDX spectra. Over a pH ranging from 2 to 8, the oxidation process of AMP was studied using phosphate buffer. The scan rates were studied over a wide range (20 to 140 mV s-1) using cyclic voltammetry. The developed sensor shows a wide linear range (1.0 × 10-8-1.0 × 10-3 M) with a detection limit of 2.32 × 10-9 M. This method can quantify AMP in pharmaceutical form, sheep meat, and liver samples.

D-optimal design as a useful tool response surface methodology for the optimization of signals from synchronous fluorescence prior to simultaneous determination of avanafil and tadalafil.

A rapid, smart and sensitive first derivative spectrofluorimetric method has been carried out for the simultaneous estimation of avanafil and tadalafil either in their pure form, tablet dosage form or spiked human plasma. The measurements of normal emission spectra or synchronous fluorescence intensity of both drugs show severe overlap which hindered their determination using normal fluorescence or synchronous intensity. Therefore, a highly sensitive first derivative synchronous fluorescence procedure was used to resolve this overlap. The method is based upon measurement of the amplitude of the first derivative of synchronous fluorescence intensity of both drugs at Δλ = 70 nm and at suitable wavelength of 396 nm and 364 nm for avanafil and tadalafil, respectively. Under the optimum conditions, the linear determination ranges are 50-1800 and 5-400 ng mL-1 with a detection limit of 12.93 and 1.46 ng mL-1 for avanafil and tadalafil, respectively. A response surface methodology was used for optimization using D-optimal design which can be used for determination of the exact optimum parameters specifically designed for this method. In addition; it is a good way to graphically clarify the relationship between various experimental variables and the synchronous fluorescence intensity.

First derivative synchronous fluorescence spectroscopy for the determination of Gatifloxacin in presence of its oxidative degradation product: Application to pharmaceutical preparation.

A highly accurate and precise spectrofluorimetric method was established for quantitation of Gatifloxacin in pure material, pharmaceutical formulations and in the existence of its oxidative degradation product. The emission was recorded at 487 nm after the excitation at 290 nm. Using micelle, sodium dodecyl sulphate (SDS), enhanced fluorescence intensity of Gatifloxacin-SDS complex. The optimization of numerous experimental conditions was carried out. The improved emission showed a suitable linear correlation between derivative synchronous fluorescence power and concentration of Gatifloxacin over the range of 10 to 100 ng/mL with a determination coefficient equals 0.9996. Studying cytotoxicity and antimicrobial susceptibility for oxidative degradation product of Gatifloxacin was carried out using Gatifloxacin as a control. In comparison, the proposed method presented a superior sensitivity and enhanced stability over the reported method.

A comparative study of different aspects in manipulating ratio spectra used for the analysis of cefradine in the presence of its alkaline degradation product.

Six stability-indicating UV-spectrophotometric methods manipulating ratio spectra were utilized for the analysis of cefradine in presence of its alkaline degradate. These methods are different forms of transformations; ratio difference, mean centering, derivative ratio using numerical differentiation, derivative ratio using Savitsky-Golay filter, continuous wavelet transform and derivative continuous wavelet transform. Water was used as a solvent and the linearity ranges were 6-26 µg/mL. Determination of accuracy and precision for the suggested procedures were executed. Assessment of specificity was run through analyzing laboratory prepared mixtures containing cefradine and its alkaline degradate. The suggested methods were useful for cefradine estimation in tablets. Statistically, the outputs obtained from the recommended and published methods reveal no significant differences.

Comparative Study Between Zero-Order Spectra-Processing and Ratio Spectra-Manipulating Methods Applied for the Determination of Isoxsuprine Hydrochloride in the Presence of Its Oxidative Degradation Product.

Four accurate, precise, and validated stability-indicating spectrophotometric methods handling either zero-order spectra or ratio spectra have been developed and compared for the analysis of isoxsuprine hydrochloride (ISX) in the presence of its oxidative degradation product. The first two methods processed zero-order spectra, namely graphical absorbance ratio or Q-Analysis and area under the curve, whereas the third and fourth methods manipulated ratio spectra, namely the ratio difference spectrophotometric method and derivative ratio. The proposed methods showed good linearity in the range of 2-23 µg/mL. The methods were tested for specificity using laboratory-prepared mixtures containing the drug and its degradation product. The proposed methods were applied for the determination of ISX in Vascular tablets and the obtained results were acceptable, with small percentage RSD values. The validity of the proposed procedures was further assessed by applying the standard addition technique, which showed no interference from excipients. The obtained results were statistically compared with those obtained by the reported method, showing no significant differences when t- and F-tests were applied.