Determining amlodipine in blood plasma by liquid chromatography coupled to tandem mass spectrometry

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.

Electro membrane extraction combined with capillary electrophoresis for the determination of amlodipine enantiomers in biological samples

Electro membrane extraction as a new microextraction method was applied for the extraction of amlodipine (AM) enantiomers from biological samples. During the extraction time of 15  min, AM enantiomers migrated from a 3  mL sample solution, through a supported liquid membrane into a 20  μL acceptor solution presented inside the lumen of the hollow fiber. The driving force of the extraction was 200  V potential, with the negative electrode in the acceptor solution and the positive electrode in the sample solution. 2-Nitro phenyl octylether was used as the supported liquid membrane. Using 10  mM HCl as background electrolyte in the sample and acceptor solution, enrichment up to 124 times was achieved. Then, the extract was analyzed using CD modified CE method for separation of AM enantiomers. Best results were achieved using a phosphate running buffer (100  mM, pH 2.0) containing 5  mM hydroxypropyl-α-CD. The range of quantitation for both enantiomers was 10-500  ng/mL. Intra- and interday RSD (n=6) were less than 14%. The limits of quantitation and detection for both enantiomers were 10 and 3  ng/mL respectively. Finally, this procedure was applied to determine the concentration of AM enantiomers in plasma and urine samples.