Facile separation of four co-formulated ternary antihypertensive drug combinations with a customized elution protocol using supercritical fluid chromatography

Columns in analytical-scale supercritical fluid chromatography: From traditional to unconventional chemistries

Within this review, we thoroughly explored supercritical fluid chromatography (SFC) columns used across > 3000 papers published from the first study carried out under SFC conditions in 1962 to the end of 2022. We focused on the open tubular capillary, packed capillary, and packed columns, their chemistries, dimensions, and trends in used stationary phases with correlation to their specific interactions, advantages, drawbacks, used instrumentation, and application field. Since the 1990s, packed columns with liquid chromatography and SFC-dedicated stationary phases for chiral and achiral separation are predominantly used. These stationary phases are based on silica support modified with a wide range of chemical moieties. Moreover, numerous unconventional stationary phases were evaluated, including porous graphitic carbon, titania, zirconia, alumina, liquid crystals, and ionic liquids. The applications of unconventional stationary phases are described in detail as they bring essential findings required for further development of the supercritical fluid chromatography technique.

Nanosensors in the detection of antihypertension drugs, a golden step for medication adherence monitoring

Hypertension is associated with structural and functional changes in blood vessels with increased arteriosclerosis, vascular inflammation, and endothelial dysfunction. Decreased adherence (compliance) to antihypertensive medications contributes significantly to morbidity and mortality in hypertensive patients. Antihypertensive drugs (AHTDs) and lifestyle changes are the main cornerstones for treating hypertension. Several approaches have been described in the literature for determining AHTDs based on different analytical techniques. Amongst biosensors are one of the most attractive tools due to their inherent advantages. Biosensors are used for the detection of wide range of biomarkers as well as different drugs in past two decades. The main focus of the present study is to review the latest biosensors developed for the detection of AHTDs. Readers of the present study will be able to familiarize themselves with biosensors as advanced and modern diagnostic tools while reviewing the most widely used AHTDs. In the present study, the routine methods are first reviewed and while examining their advantages and disadvantages, biosensors have been introduced as ideal alternative tools.

Cost-effective, green HPLC determination of losartan, valsartan and their nitrosodiethylamine impurity: application to pharmaceutical dosage forms

Angiotensin-converting enzyme inhibitors are one of the most widely used anti-hypertensive drugs which are used to reduce hypertension. In 2018, the United States Food and Drug Administration together with the European Medicine Agency declared the presence of carcinogenic nitrosamine impurities such as nitrosodiethylamine (NDEA) in some of the products, including valsartan (VLS) and losartan (LOS), and drugs' recall procedures were started. Thus, they should be controlled to be below the acceptable cancer risk level to ensure safety of the pharmaceutical products. Therefore, sensitive and reliable analytical methods were required for detection and quantitation of NDEA in bulk and finished drug products. Green analytical chemistry has received great interest to minimize the amount of organic solvents consumed without loss in chromatographic performance. A green and sensitive HPLC method was developed for the determination of NDEA in LOS and VLS using mobile phase of 0.02 M ammonium acetate adjusted to pH 7.2 and ethanol in gradient manner. Limits of detection and limits of quantification for NDEA were estimated to be 0.2 and 0.5 µg ml^-1, respectively. The standardized limits of NDEA impurity in drug substances were set as 0.56 ppm, which indicates the feasibility of its determination by the proposed conventional method without need for expensive instrumentations (e.g. MS/MS detectors) that are not found in most pharmaceutical quality control laboratories.

Cost-effective, green HPLC determination of losartan, valsartan and their nitrosodiethylamine impurity: application to pharmaceutical dosage forms

Angiotensin-converting enzyme inhibitors are one of the most widely used anti-hypertensive drugs which are used to reduce hypertension. In 2018, the United States Food and Drug Administration together with the European Medicine Agency declared the presence of carcinogenic nitrosamine impurities such as nitrosodiethylamine (NDEA) in some of the products, including valsartan (VLS) and losartan (LOS), and drugs' recall procedures were started. Thus, they should be controlled to be below the acceptable cancer risk level to ensure safety of the pharmaceutical products. Therefore, sensitive and reliable analytical methods were required for detection and quantitation of NDEA in bulk and finished drug products. Green analytical chemistry has received great interest to minimize the amount of organic solvents consumed without loss in chromatographic performance. A green and sensitive HPLC method was developed for the determination of NDEA in LOS and VLS using mobile phase of 0.02 M ammonium acetate adjusted to pH 7.2 and ethanol in gradient manner. Limits of detection and limits of quantification for NDEA were estimated to be 0.2 and 0.5 µg ml^-1, respectively. The standardized limits of NDEA impurity in drug substances were set as 0.56 ppm, which indicates the feasibility of its determination by the proposed conventional method without need for expensive instrumentations (e.g. MS/MS detectors) that are not found in most pharmaceutical quality control laboratories.

Application of supercritical fluid chromatography for separation and quantitation of 15 co-formulated binary anti-hypertensive medications using a single elution protocol

A facile supercritical fluid chromatography method is proposed to analyse 15 co-formulated binary anti-hypertensive drug combinations using a customized elution procedure. The effect of mobile phase composition, column back pressure and temperature was suitably optimized for adequate retention, analyte response and resolution. The chromatographic separation of the different drug combinations was performed on a DCPak poly(4-vinylpyridine) column (250 × 4.6 mm, 5 μm) at 125-bar pressure and 40°C using a photodiode array detector. A linear gradient of CO₂ and 0.1% formic acid in methanol provided the best elution conditions for all drug combinations. Baseline separation of the drugs was possible with resolution factor R_s ranging from 1.42 to 12.58. The method was validated for specificity, sensitivity, accuracy and precision, recovery and robustness. The limit of detection and limit of quantitation for aliskiren, amlodipine, atenolol, candesartan, hydrochlorothiazide, lisinopril, losartan, metoprolol, olmesartan, telmisartan and valsartan were in the range of 0.26-2.56 and 0.77-7.75 μg/mL, respectively. The thermodynamic study revealed that interactions of the drugs with the stationary phase were spontaneous as evident from the negative free energy values, and the separation process was enthalpy driven. The developed method was successfully employed to analyse these drugs in their co-formulated tablet formulations.