Green spectrofluorimetric quantification of aspirin, olmesartan, and metoprolol in spiked human plasma

Low dose aspirin is routinely taken with antihypertensive drugs such as olmesartan and metoprolol to avoid the cardiovascular and renal outcomes associated with high blood pressure. The first spectrofluorimetric method for quantifying aspirin, olmesartan, and metoprolol in spiked human plasma is described here. The emission/excitation wavelengths of Aspirin, olmesartan, and metoprolol were 404 nm/290 nm, 372 nm/250 nm, and 302 nm/230 nm, respectively. The native fluorescence spectra of metoprolol do not overlap with those of aspirin or olmesartan, although the spectra of aspirin and olmesartan overlap. As a result, metoprolol could be measured directly in a mixture at 302 nm following excitation at 230 nm. Using synchronous fluorescence spectrometry at Δλ = 110 allowed for the determination of olmesartan at 364 nm with no interference from aspirin and metoprolol. Coupling the synchronous fluorescence spectrometry with second-order derivative allowed for the determination of aspirin at 426 nm with no interference from olmesartan and metoprolol. The suggested approach has been validated using ICH M10 criteria for bioanalytical method validation and was effectively utilized for quantification of tested medications in human plasma with reasonable accuracy and precision findings. Furthermore, using two greenness metrics, the Green Analytical Procedure Index and the Analytical GREEnness, the suggested method obtained a high greenness score.

Rapid fluorometric determination of ticagrelor in tablets and rat plasma: Application to pharmacokinetics study

The new antiplatelet drug ticagrelor has been determined based on its native fluorescence properties. These properties were studied and optimized to develop fast, simple and sensitive spectrofluorimetric method. The study included two approaches. The first approach is depending on measuring the native fluorescence at 300 nm after excitation at 222 nm. While the second approach combined synchronous and derivative scanning modes to measure ticagrelor at 286 nm using Δ λ = 100 nm. Ticagrelor was measured in aqueous solution starting from the concentration of 200 to 5000 ng/mL in both native and first derivative synchronous approaches. The developed methods were validated in accordance with ICH guidelines to be acceptable for quality control laboratories. Lowest concentrations that could be quantitated using the native and first derivative synchronous methods were 189 and 151 ng/mL while lowest detectable concentrations were 63 and 50 ng/mL, respectively. Moreover, the derivative synchronous fluorimetric approach was utilized to determine ticagrelor at 286 nm in presence of other commonly co- administered drugs and the results demonstrate the enhanced selectivity of the proposed method. The same approach was also used to determine ticagrelor in rat plasma with acceptable recoveries. A preliminary pharmacokinetic study in rats was conducted and could be used to monitor plasma ticagrelor levels in humans.

Preconcentration of codeine in pharmaceutical and human urine samples by multi-walled carbon nanotubes and its spectrophotometric determination

A rapid and efficient solid phase extraction method was established for the preconcentration of codeine prior to its simple determination by spectrophotometry. The extraction process is based on the multi-walled carbon nanotubes (CNTs) containing –COOH functional groups. These CNTs showed a great affinity for the low quantities of codeine in certain condition. Various extraction factors including buffer type, concentration and its pH, ionic buffer, incubation time, and eluent were optimized to achieve high sensitivity. The calibration graph was linear in the codeine concentration range of 0.001–4 mg·L−1, with a detection limit (3s) of 0.4 μg·L−1. The relative standard deviation (RSD %) for the repetitive determination of 0.01, 0.5, and 2 mg·L−1 codeine (n = 5) were 1.56%, 2.01%, and 1.63%, respectively. Furthermore, comparison with other reported methods showed that the presented method has suitable characteristics. Finally the method was successfully used to accurately determine codeine in pharmaceutical and human urine samples.

Different interaction of codeine and morphine with DNA: a concept for simultaneous determination

In this study, the interaction between codeine and morphine with dsDNA was assessed at pH 7.0. Poly(diallyldimethylammonium chloride), PDDA, was used as a dispersant of MWCNTs. Using differential pulse voltammetry (DPV) at pencil graphite electrode (PGE) showed that both molecules were electrochemically oxidized due to the presence of phenolic and amino groups in their structures. When DNA was added to the solution, the electrochemical signal of codeine and morphine was decreased and shifted to more negative and positive potentials, respectively. The interaction modes were respectively electrostatic for codeine and intercalation for morphine with two anodic peaks of codeine being merged into them when DNA concentration was increased. At high DNA concentrations, a sharp anodic wave for codeine and a clear discrimination of codeine and morphine oxidation peaks were observed. Finally, a pencil graphite electrode was modified with carbon nanotubes and DNA was tested in order to determine codeine and morphine in solution. Electrochemical oxidation of codeine and morphine bonded on dsDNA/MWCNTs-PDDA/PGE was used to obtain an analytical signal. Allowing five min as an accumulation time, a linear dependence was observed between 0.05 and 40 μg mL(-1) for codeine and 0.05 and 42 μg mL(-1) for morphine. Detection limits of 0.041 and 0.043 μg mL(-1) were obtained for codeine and morphine, respectively. The biosensor was applied to validate its capability for the analysis of codeine and morphine in blood serum, urine samples and pharmaceutical formulations.

Fast and single solid phase fluorescence spectroscopic batch procedure for (acetyl) salicylic acid determination in drug formulations

A solid phase fluorescence spectroscopic batch procedure for (acetyl) salicylic acid in drug formulations have been developed. The procedure is based on the sorption of salicylic acid (SA) on Sephadex DEAE A-25 anion exchanger gel (100 mg) by equilibration from an aqueous solution (10 or 25 ml) for 5 min; the equilibrated gel is transferred into an 1 mm quartz cell and the native fluorescence of SA sorbed on it is directly measured (lambda(ex)=297 nm; lambda(em)=405 nm). Good linearity was found in the 10-200 and 5-100 microg l(-1) ranges (for 10 and 25 ml sample volume, respectively) with R.S.D. (%) of 2.8 and 1.1. The procedure was successfully applied to the determination of acetyl salicylic acid (ASA) in drug formulations after alkaline hydrolysis to yield SA.