Simultaneous determination of telmisartan and amlodipine in human plasma by LC-MS/MS and its application in a human pharmacokinetic study

Design of Experimental Approach for Development of Rapid High Performance Liquid Chromatographic Process for Simultaneous Estimation of Metoprolol, Telmisartan, and Amlodipine from Formulation: Greenness and Whiteness Evaluation

The design of an experimental approach, the Box-Behnken design, was implemented to optimize the chromatographic condition to develop a rapid HPLC procedure for quantification of a ternary mixture of metoprolol (MET), telmisartan (TEL), and amlodipine (AML) from the formulation. The perturbation plots, contour, and 3D response surface pictures were developed to study the impact of each variable on the analytes' retention time and the probable interaction between the parameters with fewer chromatographic runs. The optimized HPLC method separated the three analytes within 5 min with excellent selectivity and peak shape on a Zorbax C18 HPLC column using acetonitrile and phosphate buffer (20 mM, pH 5.8) with isocratic elution at a 1.1 mL/min flowrate. A wavelength 230 nm was utilized to monitor the elute. The validation of proposed method demonstrated a wide linearity range of 10-200 µg/mL for MET and TEL and 5-50 µg/mL for AML along with an excellent correlation coefficient. The correctness of the HPLC approach was further confirmed by excellent recovery of the added amount of analytes utilizing the standard addition technique. The recommended HPLC approach was employed safely for quality assurance of the formulation, because the evaluation of the method's greenness and whiteness confirmed the environmentally friendly nature of the approach.

A Simple UPLC/MS-MS Method for Simultaneous Determination of Lenvatinib and Telmisartan in Rat Plasma, and Its Application to Pharmacokinetic Drug-Drug Interaction Study

Lenvatinib is a multi-targeted tyrosine kinase inhibitor that inhibits tumor angiogenesis, but hypertension is the most common adverse reaction. Telmisartan is an angiotensin receptor blocker used to treat hypertension. In this study, a simple ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of lenvatinib and telmisartan, and it was applied to the pharmacokinetic drug interaction study. Plasma samples were treated with acetonitrile to precipitate protein. Water (containing 5 mM of ammonium acetate and 0.1% formic acid) and acetonitrile (0.1% formic acid) were used as the mobile phases to separate the analytes with gradient elution using a column XSelect HSS T3 (2.1 mm × 100 mm, 2.5 μm). Multiple reaction monitoring in the positive ion mode was used for quantification. The method was validated and the precision, accuracy, matrix effect, recovery, and stability of this method were reasonable. The determination of analytes was not interfered with by other substances in the blank plasma, and the calibration curves of lenvatinib and telmisartan were linear within the range of 0.2–1000 ng/mL and 0.1–500 ng/mL, respectively. The results indicate that lenvatinib decreased the systemic exposure of telmisartan. Potential drug interactions were observed between lenvatinib and telmisartan.

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.

Benefit of serum drug monitoring complementing urine analysis to assess adherence to antihypertensive drugs in first-line therapy

With obesity having doubled in the last decade, hypertension is on the rise. In one-third of hypertensive patients the metabolic syndrome is present. This might be one factor for the increasing number of prescriptions for angiotensin receptor blockers and calcium-channel blockers besides a more favorable risk-to-benefit ratio. The aim of the present study was to evaluate a therapeutic drug monitoring (TDM) method for assessment of adherence based on cut-offs in inpatients and to compare it to an established urine drug screening in outpatients. A method for quantification of calcium-channel blockers and angiotensin receptor blockers using high-performance liquid chromatography-tandem mass spectrometric analysis (LC-MS/MS) was developed and validated. The method was applied to serum samples of 32 patients under supervised medication to establish cut-off values for adherence assessment based on dose-related concentrations (DRC, calculated from pharmacokinetic data). Furthermore, corresponding urine and blood samples of 42 outpatients without supervised medication were analysed and the results compared with regard to adherence assessment. All serum concentrations measured for amlodipine (n = 40), lercanidipine (n = 14), candesartan (n = 10), telmisartan (n = 4) and valsartan (n = 10) in inpatients were above the patient specific lower DRC confirming adherence. Of 42 outpatients the identification of analytes in urine as well as the quantification in serum exhibited differing results. According to urinalysis, adherence was demonstrated in only 87.0% of prescriptions, compared to 91.3% for serum analyses. Differences were observed for amlodipine, lercanidipine and candesartan which can be explained by a higher specificity of the serum analysis approach due to pharmacokinetics. The present study confirms that assessing adherence based on serum drug concentrations with individually calculated lower DRCs is more accurate than using qualitative urine analysis. In particular, drugs with low bioavailability, low renal excretion or high metabolism rate such as lercanidipine and candesartan may lead to underestimation of adherence via urine analysis.

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.

Determination of Tryptophan and Kynurenine by LC-MS/MS by Using Amlodipine as an Internal Standard

Tryptophan is an essential amino acid that plays an important role in cell metabolism, and kynurenine is its main metabolic pathway. By using ultra-high-performance liquid chromatography coupled to electrospray ionization triple-quadrupole mass spectrometry, tryptophan and kynurenine were determined using amlodipine as an internal standard. The analysis was carried out on an ACE-C18 (4.6 mm × 50 mm, 5 μm) reversed-phase analytical column using the gradient elution mode. For quantitative determination, amlodipine was used as an internal standard. Detection was performed using multiple reaction monitoring in electrospray ionization mode at m/z 205.1 → 117.7 and 187.9 for tryptophan, m/z 209.1 → 146 and 93.9 for kynurenine, and m/z 409.2 → 294.1 for the internal standard. Good linearity of the analyte to internal standard peak area ratios was seen in the concentration range 1.25-4000 ng/mL for tryptophan and 0.5-1600 ng/mL for kynurenine. The method showed excellent linearity with regression coefficients of 0.99 for kynurenine and 0.996 for tryptophan. The limits of quantification were 0.55 ng/mL for tryptophan and 0.47 ng/mL for kynurenine. The % RSD for all analytes ranged from 0.3 to 3.4% for intraday and 0.4 to 8.9% for interday experiments. A simple LC-MS/MS method has been developed and validated for measuring Kyn and Trp by using an affordable and more easily available internal standard, which is amlodipine.

Optimization of chromatography to overcome matrix effect for reliable estimation of four small molecular drugs from biological fluids using LC-MS/MS

The article describes a systematic study to overcome the matrix effect during chromatographic analysis of gemfibrozil, rivastigmine, telmisartan and tacrolimus from biological fluids using LC-ESI-MS/MS. All four methods were thoroughly developed by the appropriate choice of analytical column, elution mode and pH of mobile phase for improved chromatography and overall method performance. Matrix effect was assessed by post-column analyte infusion, slope of calibration line approach and post-extraction spiking. The best chromatographic conditions established were: Acquity BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column with 5.0 mm ammonium acetate, pH 6.0-methanol as the mobile phase under gradient program for gemfibrozil; Luna CN (50 × 2.0 mm, 3 μm) column with a mobile phase consisting of acetonitrile-10 mm ammonium acetate, pH 7.0 (90:10, v/v) for rivastigmine; Inertsustain C₁₈ (100 × 2.0 mm, 5 μm) column using methanol-2.0 mm ammonium formate, pH 5.5 (80: 20, v/v) as the mobile phase for isocratic elution of telmisartan; and Acquity BEH C₁₈ (50 × 2.1 mm, 1.7 μm) with methanol-10 mm ammonium acetate, pH 6.0 (95:5, v/v) as mobile phase for tacrolimus. The methods were thoroughly validated as per European Medicines Agency and US Food and Drug Administration guidance and were successfully applied for pharmacokinetic studies in healthy subjects.

Application of an LC-MS/MS method for the analysis of amlodipine, valsartan and hydrochlorothiazide in polypill for a bioequivalence study

A sensitive and selective method has been proposed for the simultaneous determination of amlodipine (AML), valsartan (VAL) and hydrochlorothiazide (HCTZ) in human plasma by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The analytes and their deuterated analogs were quantitatively extracted from 100 µL human plasma by solid phase extraction on Oasis HLB cartridges. The chromatographic separation of the analytes was achieved on a Chromolith RP_18e (100 mm × 4.6 mm) analytical column within 2.5 min. The resolution factor between AML and VAL, AML and HCTZ, and VAL and HCTZ was 2.9, 1.5 and 1.4, respectively, under isocratic conditions. The method was validated over a dynamic concentration range of 0.02–20.0 ng/mL for AML, 5.00–10,000 ng/mL for VAL and 0.20–200 ng/mL for HCTZ. Ion-suppression/enhancement effects were investigated by post-column infusion technique. The mean IS-normalized matrix factors for AML, VAL and HCTZ were 0.992, 0.994 and 0.998, respectively. The intra-batch and inter-batch precision (% CV) across quality control levels was ≤ 5.56% and the recovery was in the range of 93.4%–99.6% for all the analytes. The method was successfully applied to a bioequivalence study of 5 mg AML + 160 mg VAL + 12.5 mg HCTZ tablet formulation (test and reference) in 18 healthy Indian males under fasting. The mean log-transformed ratios of C_max, AUC_0–120h and AUC_0-inf and their 90% CIs were within 90.2%–102.1%. The assay reproducibility was demonstrated by reanalysis of 90 incurred samples.

Development and validation of a high throughput LC-MS/MS method for simultaneous quantitation of pioglitazone and telmisartan in rat plasma and its application to a pharmacokinetic study

Management of cardiovascular risk factors in diabetes demands special attention due to their co-existence. Pioglitazone (PIO) and telmisartan (TLM) combination can be beneficial in effective control of cardiovascular complication in diabetes. In this research, we developed and validated a high throughput LC-MS/MS method for simultaneous quantitation of PIO and TLM in rat plasma. This developed method is more sensitive and can quantitate the analytes in relatively shorter period of time compared to the previously reported methods for their individual quantification. Moreover, till date, there is no bioanalytical method available to simultaneously quantitate PIO and TLM in a single run. The method was validated according to the USFDA guidelines for bioanalytical method validation. A linear response of the analytes was observed over the range of 0.005-10 µg/mL with satisfactory precision and accuracy. Accuracy at four quality control levels was within 94.27%-106.10%. The intra- and inter-day precision ranged from 2.32%-10.14 and 5.02%-8.12%, respectively. The method was reproducible and sensitive enough to quantitate PIO and TLM in rat plasma samples of a preclinical pharmacokinetic study. Due to the potential of PIO-TLM combination to be therapeutically explored, this method is expected to have significant usefulness in future.

Simultaneous determination of telmisartan and amlodipine in dog plasma by LC-MS-MS

A simple, rapid and sensitive method was established for the simultaneous determination of telmisartan and amlodipine in dog plasma by a HPLC-MS-MS analysis. The plasma sample preparation was a simple deproteinization by the addition of three volumes of methanol/acetonitrile mixture followed by centrifugation. The analytes and internal standard diphenhydramine were separated on a Zorbax SB-C18 column with a mobile phase of acetonitrile : water (45 : 55, v/v) at a flow rate of 0.2 mL/min with an operating temperature of 25°C. Detection was carried out by electrospray ionization in positive-ion multiple reaction monitoring mode. The calibration plots in dog plasma were linear over the ranges of 0.5-2,000 ng/mL for telmisartan and 0.5-500 ng/mL for amlodipine. The lower limit of quantification was 0.5 ng/mL for two analytes. The intra- and interday precisions (RSD%) were within 9.0%. The average recoveries of analytes were >85.0%. The method was successfully applied to the pharmacokinetic study of the two compounds after oral administration of telmisartan-amlodipine combination preparation to dogs.

Simultaneous determination of rosuvastatin and amlodipine in human plasma using tandem mass spectrometry: Application to disposition kinetics

The liquid chromatography–tandem mass spectrometric assay method for the simultaneous determination of rosuvastatin and amlodipine in human plasma using deuterated analogs as internal standards has been developed and validated. The analytes were extracted from 100 μL aliquots of human plasma via liquid–liquid extraction using a mixture of ethyl acetate and n-hexane (80:20, v/v) as an extraction solvent. The optimized mobile phase was composed of 0.1% formic acid in 5 mM ammonium acetate, methanol, and acetonitrile (20:20:60, v/v/v) and delivered at a flow rate of 0.75 mL/min. The calibration curve obtained was linear (R² ⩾ 0.999) over the concentration range of 0.52–51.77 ng/mL for rosuvastatin and 0.10–10.07 ng/mL for amlodipine. A sample turnover rate of less than 2.5 min makes it an attractive procedure in high-throughput bioanalysis of rosuvastatin and amlodipine. The present method was found to be applicable to clinical studies and the results were authenticated by incurred sample reanalysis.

Simultaneous quantification of prodrug oseltamivir and its metabolite oseltamivir carboxylate in human plasma by LC-MS/MS to support a bioequivalence study

A simple, precise and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the simultaneous determination of oseltamivir and oseltamivir carboxylate, a neuraminidase inhibitor, using their deuterated analogs as internal standards (ISs). The method involved solid phase extraction of the analytes and ISs from 200 μL human plasma with no reconstitution and drying steps. The chromatographic separation was achieved on a Symmetry C18 (100 mm×4.6 mm, 5 μm) column using 10 mM ammonium formate and acetonitrile (30:70, v/v) as the mobile phase in a run time of 2.0 min. Quantitation of analytes and ISs were done by multiple reaction monitoring on a triple quadrupole mass spectrometer in the positive ionization mode. The linearity of the method was established in the concentration range of 0.5–200 ng/mL and 2.0–800 ng/mL for oseltamivir and oseltamivir carboxylate respectively. The mean extraction recovery for oseltamivir (94.4%) and oseltamivir carboxylate (92.7%) from spiked plasma samples was consistent and reproducible. The application of this method was demonstrated by a bioequivalence study in 42 healthy Indian subjects with 75 mg oseltamivir phosphate capsules. The assay reproducibility was established by reanalysis of 151 incurred subject samples.