Development of an HPLC-UV Method for the Analysis of Drugs Used for Combined Hypertension Therapy in Pharmaceutical Preparations and Human Plasma

Alleviation of Cocaine Withdrawal and Pertinent Interactions between Salvinorin-Based Antagonists and Kappa Opioid Receptor

The kappa opioid receptor (KOR) is involved in the regulation of both the reward and mood processes. Recent reports find that the use of drugs of abuse increases the production of dynorphin and the overall activation of KOR. Long-acting KOR antagonists, such as norbinaltorphimine (nor-BNI), JDTic, and 5'-guanidinonaltrindole (GNTI), have been shown to stop depressive and anxiety-related disorders, which are the common side effects of withdrawal that can lead to a relapse in drug use. Unfortunately, these prototypical KOR antagonists are known to induce selective KOR antagonism that is delayed by hours and extremely prolonged, and their use in humans comes with serious safety concerns because they possess a large window for potential drug-drug interactions. Furthermore, their persistent pharmacodynamic activities can hinder the ability to reverse unanticipated side effects immediately. Herein, we report our studies of the lead selective, salvinorin-based KOR antagonist (1) as well as nor-BNI on C57BL/6N male mice for spontaneous cocaine withdrawal. Assessment of pharmacokinetics showed that 1 is a short-acting compound with an average half-life of 3.75 h across different compartments (brain, spinal cord, liver, and plasma). Both 1 (5 mg/kg) and nor-BNI (5 mg/kg) were shown to reduce spontaneous withdrawal behavior in mice, with 1 producing additional anti-anxiety-like behavior in a light-dark transition test (however, no mood-related effects of 1 or nor-BNI were observed at the current dosing in an elevated plus maze or a tail suspension test). Our results support the study of selective, short-acting KOR antagonists for the treatment of psychostimulant withdrawal and the associated negative mood states that contribute to relapse. Furthermore, we identified pertinent interactions between 1 and KOR via computational studies, including induced-fit docking, mutagenesis, and molecular dynamics simulations, to gain insight into the design of future selective, potent, and short-acting salvinorin-based KOR antagonists.

A Rapid HPLC Method for the Concurrent Determination of Several Antihypertensive Drugs from Binary and Ternary Formulations

A rapid, synchronized liquid chromatographic method was established for the estimation of hydrochlorothiazide (HCZ), amlodipine (AMD), olmesartan (OLM), telmisartan (TEL), and irbesartan (IRB) in binary and ternary coformulations using the same chromatographic conditions. Five analytes were separated on a Zorbax C18 column using isocratic elution with a mobile phase consisting of acetonitrile, methanol, and 20 mM phosphate buffer (pH 3.5) in a ratio of 45:20:35% v/v. The analytes were detected at a wavelength of 230 nm at ambient temperature. Furthermore, the proposed liquid chromatographic procedure was validated for linearity, precision, accuracy, stability, and robustness using an experimental design. Analytes were separated with good resolution within 3.5 min. Analytes showed good linearity in a concentration satisfactory to analyze the different ratios of these analytes in the formulations. Pareto charts showed that the flow rate and mobile phase composition have a significant effect on the peak area of analytes and hence need to be carefully controlled, however, the method is robust. Finally, the different formulations consisting of HCZ, AMD, OLM, TEL, and IRB in different ratios were analyzed with high accuracy using an optimized HPLC method and compared with reported methods. Furthermore, the reported HPLC procedure is simple, rapid, and accurate and therefore can used for regular quality control of binary and ternary formulations using the same stationary and mobile phase.

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.

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.

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.

Valsartan

Valsartan is an antihypertensive drug which selectively inhibits angiotensin receptor type II. Generally, valsartan is available as film-coated tablets. This review summarizes thermal analysis, spectroscopy characteristics (UV, IR, MS, and NMR), polymorphism forms, impurities, and related compounds of valsartan. The methods of analysis of valsartan in pharmaceutical dosage forms and in biological fluids using spectrophotometer, CE, TLC, and HPLC methods are discussed in details. Both official and nonofficial methods are described. It is recommended to use LC-MS method for analyzing valsartan in complex matrices such as biological fluids and herbal preparations; in this case, MRM is preferred than SIM method.

Development and Validation of a LC-MS/MS Method for the Simultaneous Estimation of Amlodipine and Valsartan in Human Plasma: Application to a Bioequivalence Study

A reliable, simple, and robust liquid chromatography-tandem mass spectro-metric (LC-MS/MS) method has been developed and validated that employs solid-phase extraction for the simultaneous estimation of amlodipine and valsartan in human K₃EDTA plasma using amlodipine-d4 and valsartan-d9 as internal standards. Chromatographic separation of amlodipine and valsartan was achieved on the Luna C18 (2)100A (150 × 4.6 mm, 5 μm) column using acetonitrile: 5 mM ammonium formate solution (80:20, v/v) as the mobile phase at a flow rate of 0.8 mL/min in isocratic mode. Quantification was achieved using an electrospray ion interface operating in positive mode, under multiple reaction monitoring (MRM) conditions. The assay was found to be linear over the range of 0.302–20.725 ng/mL for amlodipine and 6.062–18060.792 ng/mL for valsartan. The method has shown good reproducibility, as intra- and interday precisions were within 10% and accuracies were within 8% of nominal values for both analytes. The method was successfully applied for the bioequivalence study of amlodipine and valsartan after oral administration of a fixed dose of the combination. Additionally, as required by the current regulatory bodies, incurred sample reanalysis was performed and found to be acceptable.