Spectrofluorimetric determination of aliskiren in dosage forms and urine

Development and Greenness Evaluation of Spectrofluorometric Methods for Flibanserin Determination in Dosage Form and Human Urine Samples

Green, economic and sensitive two spectrofluorometric methods were developed for the quantitation of flibanserin (FB) in different matrices, which are based on FB native fluorescence properties. The first technique depends on measuring the relative fluorescence intensity of FB directly at emission and excitation wavelengths(λ_em/λ_ex) (371 nm/247 nm), while the second technique is a first derivative (D¹) spectrofluorometric method, which depends on measuring the peak amplitudes at 351 nm. Linear regressions were observed in the range of 0.1–1.5 μg/mL for both methods. Moreover, both methods were efficiently extended to analyze FB in human urine, indicating the ultra-sensitivity of the methods, and linear regression was found within a range 0.05–0.7 μg/mL for both methods. Excellent selectivity of the proposed methods and good recoveries were obtained upon the analysis of FB in pharmaceutical dosage form and human urine samples without interference from matrix components with acceptable ranges, from 98.86 to 101.46% and from 98.08 to 102.37%, respectively. Greenness of the developed methods was assessed using the national environmental method index (NEMI) and Analytical Eco-scale and Green Analytical Procedure Index (GAPI). The three approaches confirmed that the developed methods are green, safe and environment-friendly.

A simple and rapid spectrofluorometric determination of pomalidomide in spiked plasma and urine. Application to degradation studies

A rapid and accurate spectrofluorimetric method for the determination of pomalidomide was developed and validated based on the measurement of its native fluorescence without the need for any derivatization and separation for the first time. The fluorescence intensity of the drug in acetonitrile solution allowed precise detection at 460 nm after excitation at 296 nm. The calibration curve was linear in the concentration range 31.0-500.0 ng/ml. Limit of detection and limit of quantification were found to be 8.04 and 24.36 ng/ml, respectively. Sensitive results allowed the drug to be detected with good recovery (75.46-109.72%) in human plasma and urine using the developed method. The proposed method was validated in terms of linearity, sensitivity, precision, accuracy, recovery, and stability parameters. Pomalidomide was subjected to degradation under various stress conditions (hydrolytic, oxidative and thermal) to demonstrate that the method was stable, indicating and identifying possible degradation products. In addition, the drug was exposed to electrochemical degradation using the chronoamperometry technique for the first time. Characterization of pomalidomide degradation products obtained because of oxidative degradation and electrochemical degradation was carried out using attenuated total reflection Fourier transform infrared spectroscopy, mass spectrometry and high performance liquid chromatography - mass spectrometry methods and possible structures were proposed.

Electrochemical simulation of three novel cardiovascular drugs phase I metabolism and development of a new method for determination of them by liquid chromatography coupled with tandem mass spectrometry

In this study electrochemistry (EC) coupled with electrospray ionization mass spectrometry (ESI-MS) was used to study the metabolic fate of three novel cardiovascular drugs: rivaroxaban (RIV), aliskiren (ALS), and prasugrel (PRS). Mimicry of the oxidative phase I metabolism was achieved in a simple amperometric thin-layer cell equipped with a boron-doped diamond (MD) working electrode. Structures of the electrochemically-generated metabolites were elucidated from MS/MS experiments. Additionally, a sensitive, specific, and rapid ultra-high performance liquid chromatography-tandem mass spectrometer (UHPLC-MS/MS) method has been developed and validated for the selected drugs in human urine samples. Three different sample preparation methods were compared and finally, sample preparation was accomplished through an ultrasound-assisted emulsification microextraction process (USAEME). The drugs were detected using a triple quadrupole tandem mass spectrometer by multiple reaction monitoring via an electrospray ionization source with positive ionization mode (ESI(+)). The results obtained by EC-MS were compared with conventional in vivo studies by analyzing urine samples from patients. Data from in vivo experiments showed good agreement with the data from electrochemical oxidation. Thus, EC-MS is very well-suited for the simulation of the oxidative metabolism of rivaroxaban, aliskiren, and prasugrel as well. Moreover, electrochemical conversion of target compounds appears to be a new in vitro technology for the prediction of potential metabolites.