Development and validation of a HPLC-PDA bioanalytical method for the simultaneous estimation of Aliskiren and Amlodipine in human plasma

RP-HPLC-Based Bioanalytical Approach for Simultaneous Quantitation of Cinnarizine and Domperidone in Rat Plasma

An accurate, precise and sensitive reverse-phase high-performance liquid chromatography (RP-HPLC) bioanalytical approach was developed for the simultaneous estimation of cinnarizine (CIN) and domperidone (DOM) in rat plasma using irbesartan (IRB) as an internal standard (IS). The proposed RP-HPLC approach was validated as per the latest ICH M10 guidelines. The analytes (CIN and DOM) and IS were extracted from plasma samples using the protein precipitation strategy. Chromatographic separation is accomplished by a C18 SunfireTM (5 µm, 250 mm × 4.6 mm) analytical column, using an isocratic mobile phase consisting of acetonitrile-methanol in 30:70 proportions at a flow rate of 1 mL/min. The detection of all three constituents was recorded at a wavelength of 270 nm with a UV detector. DOM, CIN and IS were eluted at 3.2, 4.5 and 6.1 min, respectively, utilizing a total run time of 10 min. The lower limit of quantification (LLOQ) was 5 ng/mL for CIN and DOM in rat plasma. The proposed RP-HPLC approach was linear in the 5–200 ng/mL range for CIN and DOM. The recovery of the method was greater than 95%, and the relative uncertainty was less than 2%, indicating that the proposed bioanalytical approach was accurate and precise. The limit of detection was established as 1.1 ng/mL for CIN and 1.7 ng/mL for DOM. The created approach was found to be robust and passed all validation criteria; thus, the proposed RP-HPLC approach can be employed successfully for the simultaneous assessment of CIN and DOM in rat plasma.

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.

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.

Effects of Danshen tablets on pharmacokinetics of amlodipine in rats

CONTEXT

Danshen tablets (DST), an effective traditional Chinese multi-herbal formula, are often combined with amlodipine (ALDP) for treating coronary heart disease.

OBJECTIVE

This study investigated the effects of DST on the pharmacokinetics of ALDP and the potential mechanism.

MATERIALS AND METHODS

The pharmacokinetics of ALDP (1 mg/kg) in male Sprague-Dawley rats (n = 6), with or without pretreatment of DST (100 mg/kg for 7 d), were investigated using LC-MS/MS. The effects of DST on the metabolic stability of ALDP were also investigated using rat liver microsomes (RLM).

RESULTS

The results indicated that C_max (16.25 ± 2.65 vs. 22.79 ± 2.35 ng/ml), AUC_(0-t) (222.87 ± 59.95 vs. 468.32 ± 69.87 n gh/ml), and t_1/2 (10.60 ± 1.05 vs. 14.15 ± 1.59 h) decreased significantly when DST and ALDP were co-administered, which suggested that DST might influence the pharmacokinetic behaviour of ALDP when they are co-administered. The metabolic stability of ALDP was also decreased (23.6 ± 4.7 vs. 38.9 ± 5.2) with the pretreatment of DST.

DISCUSSION AND CONCLUSIONS

This study indicated that DST could accelerate the metabolism of ALDP in RLM and change the pharmacokinetic behaviours of ALDP. Accordingly, these results showed that the herb-drug interaction between DST and ALDP might occur when they were co-administered. Therefore, the clinical dose of ALDP should be increased when DST and ALDP are co-administered.

Effect Of epigallocatechin-3-gallate on the pharmacokinetics of amlodipine in rats

This study investigates the effect of epigallocatechin-3-gallate (EGCG), a major ingredient of green tea, on the pharmacokinetics of amlodipine in rats. The pharmacokinetics of orally administered amlodipine (1 mg/kg) with or without EGCG pretreatment (30 mg/kg/day for 10 days) were investigated. Plasma concentrations of amlodipine were determined by using a sensitive and reliable liquid chromatography with tandem mass spectroscopy (LC-MS/MS) method. The effects of EGCG on the metabolic stability of amlodipine were investigated by using rat liver microsome incubation systems. The results indicated that when the rats were pretreated with EGCG, the C_max of amlodipine increased from 16.32 ± 2.57 to 21.44 ± 3.56 ng/mL (p < 0.05), the T_max decreased from 5.98 ± 1.25 to 4.01 ± 1.02 h (p < 0.05), and the AUC_0-t increased from 258.12 ± 76.25 to 383.34 ± 86.95 μg h L^-1 (p < 0.05), which suggested that the pharmacokinetic behavior of amlodipine was affected after oral co-administration of EGCG. Additionally, the metabolic half-life was prolonged from 31.3 ± 5.6 to 52.6 ± 7.9 min (p < 0.05) with the pretreatment of EGCG. It can be speculated that the drug-drug interaction between EGCG and amlodipine might occur, which might have resulted from the metabolism inhibition of amlodipine by EGCG when they were co-administered.

Electrochemical simulation of three novel cardiovascular drugs phase I metabolism and development of a new method for determination of them by liquid chromatography coupled with tandem mass spectrometry

In this study electrochemistry (EC) coupled with electrospray ionization mass spectrometry (ESI-MS) was used to study the metabolic fate of three novel cardiovascular drugs: rivaroxaban (RIV), aliskiren (ALS), and prasugrel (PRS). Mimicry of the oxidative phase I metabolism was achieved in a simple amperometric thin-layer cell equipped with a boron-doped diamond (MD) working electrode. Structures of the electrochemically-generated metabolites were elucidated from MS/MS experiments. Additionally, a sensitive, specific, and rapid ultra-high performance liquid chromatography-tandem mass spectrometer (UHPLC-MS/MS) method has been developed and validated for the selected drugs in human urine samples. Three different sample preparation methods were compared and finally, sample preparation was accomplished through an ultrasound-assisted emulsification microextraction process (USAEME). The drugs were detected using a triple quadrupole tandem mass spectrometer by multiple reaction monitoring via an electrospray ionization source with positive ionization mode (ESI(+)). The results obtained by EC-MS were compared with conventional in vivo studies by analyzing urine samples from patients. Data from in vivo experiments showed good agreement with the data from electrochemical oxidation. Thus, EC-MS is very well-suited for the simulation of the oxidative metabolism of rivaroxaban, aliskiren, and prasugrel as well. Moreover, electrochemical conversion of target compounds appears to be a new in vitro technology for the prediction of potential metabolites.