Validated LC-MS/MS Method for the Simultaneous Determination of Amlodipine and Its Major Metabolites in Human Plasma of Hypertensive Patients

Opportunities of Amlodipine as a Potential Candidate in the Evaluation of Drug Compliance during Antihypertensive Therapy

Background and Objectives: Blood pressure measurement is essential evidence to establish that the chosen medicine and dosage are appropriate, and also indirectly indicates whether the medicine is being used at all. Therefore, current research compares adherence to the target blood pressure at home and in the hospital between different age groups, using similar combinations of the drugs prescribed by the doctor within ongoing antihypertensive therapy. Moreover, it is very important to develop a method for the determination of amlodipine and its metabolite, which would suitable for clinical applications, when the result is needed as quick as possible. Materials and Methods: This prospective study included patients aged ≥18 years who were diagnosed with hypertension. Subjects were divided into two age groups according to European Society of Cardiology (ESC) hypertension guidelines; older patients (≥65 years) and adult patients (<65 years). Assessment of adherence rate to antihypertensive medications was performed using a measurement of systolic blood pressure and comparing this to ESC hypertension guideline data. A simple liquid chromatography-tandem mass spectrometer (LC-MS/MS) method for determination of amlodipine and dehydroamlodipine was developed and validated according to the European Medicines Agency guideline on bioanalytical method validation at the Latvian Institute of Organic Synthesis. Results: A total of 81 patients with arterial hypertension were enrolled in this study. A significant number of patients were overweight (N = 33, 40.7%) and obese (N = 36, 44.4%). To control arterial hypertension, 70 (86.4%) patients used fixed-dose combinations, where one of the components was amlodipine. Practically, 36 (44.4%) hypertensive subjects were not able to comply with target blood pressure. Nonetheless, 38 (46.9%) patients who received fixed-dose combinations were able to comply with target blood pressure. Conclusions: Adherence to ESC hypertension guideline proposed target blood pressure was relatively low among hypertensive subjects even though a significant number of patients were taking fixed-dose combinations. Therefore, optimizing prevention, recognition, and care of hypertensive young adults require intensive educational interventions. Moreover, survey data suggest that therapeutic drug monitoring using the validated simple, sensitive LC-MS/MS method is pivotal for further understanding factors influencing adherence.

An LC-MS/MS Method for Determination of Triple Drugs Combination of Valsartan, Amlodipine and Hydrochlorothiazide in Human Plasma for Bioequivalence Study

Background:

Current guidelines for the treatment of hypertension recommend combination therapy, which intends to control blood pressure and enhance cardiovascular protection.

Materials and Methods:

A sensitive, reliable and selective tandem mass spectrometry (LC-MS/MS) method has been developed for simultaneous quantification of amlodipine (AML), valsartan (VAL) and hydrochlorothiazide (HCTZ) in human plasma. The chromatographic system was equipped with ACE 5 C8 (50 X 2.1 mm) column and utilized a mobile phase composition of 0.5 mM Ammonium Chloride & 0.04% FA-Methanol (45:55% v/v). The method used three internal standards; AML-D4, HCTZ-D2 C13 and VAL-D3 with 10% intra- and inter-day precision, and 6% bias for all the analytes.

Results:

The assay was found to be linear with R-2 > 0.998, and the limits of quantification for AML, VAL and HCTZ were 0.2, 50.0 and 2.0 ng/mL, respectively. The analytes were found to be stable in plasma samples over short and long term storage.

:

The developed method is rapid with a run time of 3.5 min and cost-effective since the simple sample preparation method is adopted. This method was successfully applied for the bioequivalence study of AML, VAL, and HCTZ in human plasma after administration of the fixed-dose combination tablet of (10/160/25 mg). Pharmacokinetic parameters (Cmax and AUC0-72) for AML and (Cmax, AUC0-t, AUC0-∞) for VAL and HCTZ were used for bioequivalence assessment. These were determined by noncompartmental analysis of concentration data.

Conclusion:

The result showed 90% confidence intervals (obtained by ANOVA) which were within the predefined ranges. As a consequence, this method can be successfully applied for measuring and quantifying a large number of samples.

Postmortem fatal and non-fatal concentrations of amlodipine

Amlodipine is a dihydropyridine calcium channel blocker widely used in the treatment of high blood pressure and coronary heart disease. Intoxication can lead to reflex tachycardia following massive hypotension and death. The objective of this work was to study the post-mortem concentrations of amlodipine in 62 patients in order to determine whether the use of the reference concentrations from the living patients was applicable in postmortem setting, and to define more precisely the fatal and non-fatal postmortem concentrations of amlodipine. The amlodipine concentrations were measured in femoral whole blood by LC-MS/MS validated method. When sufficient information was available, the data were classified into 2 different groups, based on the conclusions of the autopsy and toxicological results: G1: non-toxic death and G2: fatal poisoning involving amlodipine alone or as part of a multidrug poisoning. The median concentration of amlodipine [1st quartile - 3rd quartile] of the whole population (n = 62) was 81 [42-134] ng/mL. Twenty-two cases were classified as G1 and thirteen as G2. The observed median [1st quartile - 3rd quartile] concentration of amlodipine was 66 [40.5-79.5] ng/mL in G1 and 240 [170-404] ng/mL in G2. The median concentrations observed in "non-toxic" deaths (66 ng/mL) were three times higher than those usually observed in living patients. Amlodipine distribution ratio between plasma and whole blood concentrations seems insufficient to explain this difference and postmortem redistribution from organs should be considered, and could suggest the same redistribution pattern for other drugs belonging to the same family.

Relationships between endogenous CYP3A markers and plasma amlodipine exposure and metabolism in early postpartum and non-peripartum women with hypertension

OBJECTIVE

This study aimed to evaluate the relationship between endogenous CYP3A markers and plasma amlodipine (AML) exposure and metabolism parameters in early postpartum and non-peripartum women.

METHODS

Twenty-four AML-treated early postpartum women with hypertensive disorders of pregnancy and 30 non-peripartum women with essential hypertension were enrolled. Blood samples for determination of CYP3A markers including total cholesterol-adjusted 4β-hydroxycholesterol (4β-OHC/TC), 25-hydroxyvitamin D (25-OHD), and AML and its metabolites in plasma were collected at 24 h after the AML treatment.

RESULTS

The plasma 4β-OHC/TC in postpartum women was higher than that in non-peripartum women, while the plasma 25-OHD was lower. The postpartum women had a lower plasma AML concentration and its metabolic ratio was higher. The plasma 4β-OHC/TC decreased as the number of days post-delivery increased. The plasma AML concentration increased as the number of days post-delivery increased, while the metabolic ratio of AML declined slightly. Tendency toward negative correlations between the plasma 4β-OHC/TC but not 25-OHD, and AML concentration were observed in both postpartum and non-peripartum women. In both groups, the plasma 4β-OHC/TC was correlated with the metabolic ratio of AML.

CONCLUSIONS

The early postpartum women had higher plasma 4β-OHC and AML metabolism. The plasma 4β-OHC had positive relationships with amlodipine metabolism in both women groups. AML metabolism and plasma 4β-OHC may be useful as CYP3A markers in early postpartum and non-peripartum women.

UHPLC-MS/MS assay for simultaneous determination of amlodipine, metoprolol, pravastatin, rosuvastatin, atorvastatin with its active metabolites in human plasma, for population-scale drug-drug interactions studies in people living with HIV

Thanks to highly active antiretroviral treatments, HIV infection is now considered as a chronic condition. Consequently, people living with HIV (PLWH) live longer and encounter more age-related chronic co-morbidities, notably cardiovascular diseases, leading to polypharmacy. As the management of drug-drug interactions (DDIs) constitutes a key aspect of the care of PLWH, the magnitude of pharmacokinetic DDIs between cardiovascular and anti-HIV drugs needs to be more thoroughly characterized. To that endeavour, an UHPLC-MS/MS bioanalytical method has been developed for the simultaneous determination in human plasma of amlodipine, metoprolol, pravastatin, rosuvastatin, atorvastatin and its active metabolites. Plasma samples were subjected to protein precipitation with methanol, followed by evaporation at room temperature under nitrogen of the supernatant, allowing to attain measurable plasma concentrations down to sub-nanogram per milliliter levels. Stable isotope-labelled analytes were used as internal standards. The five drugs and two metabolites were analyzed using a 6-min liquid chromatographic run coupled to electrospray triple quadrupole mass spectrometry detection. The method was validated over the clinically relevant concentrations ranging from 0.3 to 480 ng/mL for amlodipine, atorvastatin and p-OH-atorvastatin, and 0.4 to 480 ng/mL for pravastatin, 0.5 to 480 ng/mL for rosuvastatin and o-OH-atorvastatin, and 3 to 4800 ng/mL for metoprolol. Validation performances such as trueness (95.4-110.8%), repeatability (1.5-13.4%) and intermediate precision (3.6-14.5%) were in agreement with current international recommendations. Accuracy profiles (total error approach) were lying within the limits of ±30% accepted in bioanalysis. This rapid and robust UHPLC-MS/MS assay allows the simultaneous quantification in plasma of the major currently used cardiovascular drugs and offers an efficient analytical tool for clinical pharmacokinetics as well as DDIs studies.