Spectrofluorimetric determination of amlodipine in human plasma without derivatization

Application of a white and green spectrofluorimetric approach for facile quantification of amlodipine, a hypotensive drug, in batch materials, dosage forms, and biological fluids; content homogeneity testing

The suggested study adheres to a particular protocol to ensure that the process is environmentally friendly and sustainable. It is worth mentioning that several tools have been adopted as prospective measures of the method greenness. Fortunately, the established analytical method is identified as white by the white analytical chemistry (WAC) concept, which uses the red/ green/blue color scheme (RGB 12 tool) to combine ecological and functional factors for the first time in studying of the cited drug. Amlodipine (AMD), a cardiovascular treating agent, belongs to the dihydropyridine class of oral calcium channel-blocking agents. This article presents a novel, simple, green, one-pot-processed, fast, and ultrasensitive fluorimetric approach for monitoring and assessment of AMD using molecular-size-dependent fluorescence augmentation of the light scattering-driven signal of eosin, a biological stain at a wavelength of 415 nm. This enhancement was directly proportional to the size of the produced complex. The linearity range was from 30 to 900 ng mL-1 , with corresponding sensitivity limits (detection and quantitation levels) of 9.2 and 28 ng mL-1 , respectively. The planned approach was also successfully used to track AMD content in bulk, dosage forms, and bio-fluids (human plasma and urine). The developed method's eco-friendliness was established by different eco-rating metric tools.

Electrochemical sensing platform for the simultaneous femtomolar detection of amlodipine and atorvastatin drugs

The development of a proficient and ultra-high sensitive functionalized electrode for accurate analysis of drugs is a long-standing challenge. Herein, we report an electrochemical nanocomposite scaffold, comprising of silver nanoparticles integrated with functionalized carbon nanotubes (COOH-CNTs/Ag/NH₂-CNTs) for the simultaneous quantification of two widely used amlodipine (AM) and atorvastatin (AT) drugs. The sandwiched nanocomposite materials were thoroughly characterized morphologically and structurally. The nanocomposite COOH-CNTs/Ag/NH₂-CNTs immobilized over glassy carbon electrode catalyzed electron transfer reactions at the electrode–electrolyte interface and facilitated detection of targeted drugs, as revealed by the significant decrease in oxidation potentials at 879 mV and 1040 mV and improved current signals. Electrochemical characterization and testing show that the functionalized porous architecture with a large effective surface area is a promising scaffold for the sensing of a binary mixture of AM and AT with limits of detection in the femtomolar range (77.6 fM, and 83.2 fM, respectively). Besides, the specificity, stability, and reliability of the electrochemical sensing platform in simple and complex biological and pharmaceutical samples with high percentage recoveries highlight its scope for practical applications. Computational studies supported the experimental outcomes and offered insights about the role of modifier in facilitating electron transfer between transducer and analytes.

Development of an ultra-sensitive electrochemical platform for the simultaneous detection of two high blood pressure drugs.

Direct Visualization of Amlodipine Intervention into Living Cells by Means of Fluorescence Microscopy

Amlodipine, a unique long-lasting calcium channel antagonist and antihypertensive drug, has weak fluorescence in aqueous solutions. In the current paper, we show that direct visualization of amlodipine in live cells is possible due to the enhanced emission in cellular environment. We examined the impact of pH, polarity and viscosity of the environment as well as protein binding on the spectral properties of amlodipine in vitro, and used quantum chemical calculations for assessing the mechanism of fluorescence quenching in aqueous solutions. The confocal fluorescence microscopy shows that the drug readily penetrates the plasma membrane and accumulates in the intracellular vesicles. Visible emission and photostability of amlodipine allow confocal time-lapse imaging and the drug uptake monitoring.

An enhanced first derivative synchronous spectrofluorimetric method for determination of the newly co-formulated drugs, amlodipine and celecoxib in pharmaceutical preparation and human plasma

BACKGROUND

A new combination of amlodipine and celecoxib has been recently introduced in order to relieve the symptoms of osteoarthritis and help treat hypertension that commonly associated with osteoarthritis.

OBJECTIVE

The current study is the first to develop and optimize a sensitive, simple and accurate first derivative synchronous spectrofluorimetric method for the simultaneous determination of amlodipine and celecoxib in bulk powder, pharmaceutical preparation and spiked human plasma.

METHOD

The method implies the use of synchronous methodology using Δλ = 100 nm and measuring the fluorescence amplitudes of the first derivative each at the zero-crossing point of the other. For amlodipine and celecoxib, the emission wavelengths were at 455 nm and 368 nm, after excitation at 367 nm and 264 nm, respectively.

RESULTS

The method was found to be linear over a wide concentration ranges of (5-600 ng/ml), (100-2000 ng/ml) with lower limits of detection of (1.16 ng/ml) and (17.16 ng/ml) for amlodipine and celecoxib, respectively. Enhancement of the fluorescence intensity was achieved by complex formation between the studied drugs and the surfactant sodium dodecyl sulfate and optimizing other experimental conditions. The method was further extended for application for determination of the studied drugs in spiked human plasma with excellent % recoveries of (95.20 ± 6.095) and (98.67 ± 6.394) for amlodipine and celecoxib, respectively. Validation of the method was successfully implemented according to recommendations delivered by guidelines of the International Conference on Harmonization.

Analytical and Bioanalytical Techniques for the Quantification of the Calcium Channel Blocker - Amlodipine: A Critical Review

Hypertension is a condition in which blood pressure is elevated to an extent where benefit is obtained from blood pressure lowering. The risk of complications is proportional to the level that blood pressure raises. Calcium channel blockers are a class of compounds used in the treatment of hypertension. The dihydropyridine (DHP) group, a subclass of the calcium channel blocker works almost exclusively on L-type calcium channels in the peripheral arterioles and reduce blood pressure by reducing total peripheral resistant. Long acting DHP is preferred because they are more convenient for patients and avoid the large fluctuations in plasma drug concentration which are associated with side effects. Amlodipine is the most distinct DHP and the most popular. The drug was patented in the year 1986 and its commercial sale began by 1990. The current article provides a state of art about the analytical and bioanalytical techniques available for the quantification of drug as a single entity and in combined pharmaceutical formulations between 1989 and 2019.

[Features of the determination of amlodipine in a biological material]

The purpose of the work is to determine the optimal conditions for isolating amlodipine, to purify it by the method of column chromatography and to develop a method for detecting it in biological material. TLC, GC-MS, low pressure column chromatography, and HPLC were used for analysis. We studied the comparative isolation of amlodipine from biological material using 13 isolating agents of organic nature, water, and aqueous solutions. The use of acetone as an insulating agent for the extraction of amlodipine from tissues of cadaver organs has been substantiated. The possibility of purification of the analyzed compound from the endogenous substances of the biomaterial is shown by the method of reversed phase chromatography in a column of the Silasorp S-18 sorbent of 30 μm. A technique has been developed for detecting amlodipine in the tissues of cadaveric organs (liver), which corresponds to the necessary parameters of linearity, selectivity, accuracy, precision and stability. The limits of detection and quantification of amlodipine by the proposed method are 0.25·10^-6 and 4.0·10^-6 g, respectively, in 1 g of the biomaterial.

Spectrofluorimetric determination of eptifibatide in human plasma and dosage form

A spectrofluorimetric method for the determination of eptifibatide is presented based on its native fluorescence. The type of solvent and the wavelength of maximum excitation and emission were carefully selected to optimize the experimental conditions. Under the specified experimental conditions, the linearities obtained between the emission intensity and the corresponding concentrations of eptifibatide were in the range 0.1-2.5 μg/ml for the calibration curve constructed for direct determination of eptifibatide in dosage form and 0.05-2.2 μg/ml for the calibration curve constructed in spiked human plasma with a good correlation coefficient (r > 0.99). The lower limit of quantification for the calibration curve constructed in human plasma was 0.05 μg/ml. Recovery results for eptifibatide in spiked plasma samples and in dosage form, represented as mean ± % RSD, were 95.17 ± 1.94 and 100.29 ± 1.33 respectively. The suggested procedures were validated according to the International Conference on Harmonization (ICH) guidelines for the direct determination of eptifibatide in its pure form and dosage form and United States Food and Drug Administration (US FDA) Guidance for Industry, Bioanalytical Method Validation for the assay of eptifibatide in human plasma.

Simultaneous colorimetric detection of four drugs in their pharmaceutical formulations using unmodified gold nanoparticles as a probe

Schematic representation for the aggregation of unmodified Au NPs induced by four drugs (venlafaxine, imipramine, amlodipine, and alfuzosin).