Simultaneous determination of captopril and hydrochlorothiazide by time-resolved chemiluminescence with artificial neural network calibration

Chemiluminescence data modeling using parallel factor analysis for the simple and sensitive determination of diphenoxylate in human plasma and tablets

In this study, a chemiluminescence (CL) method was developed to determine diphenoxylate in tablets and human plasma. This is the first CL method proposed to determine diphenoxylate. Creating three-dimensional data caused the parallel factor analysis algorithm (PARAFAC) to be used for the first time in CL methods. The method is based on the fact that diphenoxylate enhances the weak CL produced in the reaction of Ru(phen)3 2+ and acidic Ce(IV), and the concentration of Ce(IV) solution has a different effect on the CL response of diphenoxylate and the blank plasma. The calibration curve was linear from 4.0 × 10-8 to 1.6 × 10-6 mol L-1 (R2 = 0.9954), and the detection limit was 1.3 × 10-8 mol L-1 (S/N = 3). The sampling rate was about 30 samples per hour, and the % RSD for 10 repeated measurements of 4 × 10-7 mol L-1 diphenoxylate was 5.4%. The interference effects of some ions, amino acids, and common additives were also investigated. The CL method was successfully used to determine diphenoxylate in tablets, and the results were statistically confirmed by the reference method. The proposed CL method and the PARAFAC algorithm were successfully used to determine the concentration of diphenoxylate in human blood plasma samples.

AQbD TLC-densitometric method approach along with green fingerprint and whiteness assessment for quantifying two combined antihypertensive agents and their impurities

Preserving the environment, reducing the amount of waste resulting from chemical trials, and reducing the amount of energy consumed have currently become a pivotal global trend. An analytical quality by design (AQbD) based eco-friendly TLC-densitometric method was implemented for quantifying two antihypertensive agents, captopril (CPL) and hydrochlorothiazide (HCZ), along with their impurities; captopril disulphide (CDS), chlorothiazide (CTZ) and salamide (SMD). The analytical target profile (ATP) was first identified, followed by selecting the critical analytical attributes (CAAs), such as retardation factors and resolution between the separated peaks. Critical method parameters (CMPs) that may have a crucial influence on CAAs were identified and emanated through the quality risk assessment phase. A literature survey-based preliminary studies were performed, followed by optimization of the selected CMPs through a custom experimental design to attain the highest resolution with optimum retardation factors. Moreover, method robustness was also tested by testing the design space. Complete separation of the drugs and their impurities was achieved using ethyl acetate: glacial acetic acid (6: 0.6, v/v) as a developing system applied to a 12 cm length TLC plate at room temperature with UV scanning at 215 nm. Calibration graphs were found to be linear in the ranges of (0.70-6.00), (0.10-2.00), (0.20-1.00), (0.07-1.50) and (0.05-1.00) µg/band corresponding to CPL, HCZ, CDS, CTZ, and SMD, respectively. Four different green metric tools were used to evaluate the greenness profile of the proposed method, and results showed that it is greener than the reported HPLC method. Method whiteness assessment was also conducted. Moreover, the method performance was evaluated following the ICH guidelines, and the outcomes fell within the acceptable limits. The developed method could be approved for routine assay of the cited components in their pharmaceutical formulations and bulk powder without interference from the reported impurities. The issue of concern is saving money, especially in developing countries.

Greenness assessment of UPLC/MS/MS method for determination of two antihypertensive agents and their harmful impurities with ADME/TOX profile study

Hypertension is described by the world health organization (WHO) as a serious medical problem that significantly affects the heart, brain and kidneys. It is a major cause of premature death worldwide. The present study aims to quantify the combination of captopril (CPL), hydrochlorothiazide (HCZ) and their harmful impurities; captopril disulphide (CDS), chlorothiaizde (CTZ) and salamide (SMD). In-silico study was conducted for estimation of pharmacokinetic parameters (ADMET) as well as toxicity profile of the proposed impurities. The results showed that the three impurities under investigation had poor permeability to CNS and cannot pass the blood-brain barrier (BBB), reducing the likelihood of causing side effects in the brain. On the other hand, all studied impurities were found to be hepatotoxic. In consequence, a highly sensitive and green ultra-performance liquid chromatography- tandem mass spectrometric (UPLC/MS/MS) method was developed and validated for separation of the cited drugs in the presence of their harmful impurities; methanol and 0.1% formic acid (90:10, v/v) mixture was used as a mobile phase, eluted at a constant flow rate of 0.7 mL/min at room temperature. Detection was adopted using a tandem mass spectrometer in a positive mode only for CPL and negative mode for HCZ, CDS, CTZ and SMD. Separation was performed within 1 min. Calibration graphs were found to be linear in the ranges of (50.0-500.0 ng mL-1), (20.0-500.0 ng mL-1), (10.0-250.0 ng mL-1), (5.0-250.0 ng mL-1) and (20.0-400.0 ng mL-1) corresponding to CPL, HCZ, CDS, CTZ and SMD, respectively. Additionally, comparative study of greenness profile was established for the proposed and reported methods using five green metric tools. The proposed method was found to be greener than the reported HPLC method. The developed (UPLC/MS/MS) method was validated according to (ICH) guidelines and it was found to has greater sensitivity, shorter analysis time and lower environmental impact compared to the reported methods.

A chemiluminescence reagent free method for the determination of captopril in medicine and urine samples by using trivalent silver

A novel flow-injection chemiluminescence (FI-CL) method free of CL reagent was developed for the determination of captopril based on its enhancing effect on the CL derived from diperiodatoargentate(III)-sulfuric acid system. Compared with the conventional CL system, the CL system based on trivalent silver was characterized of good selectivity for the absence of CL reagent. The CL mechanism was discussed through CL spectra and UV-vis absorption spectra. The conditions of the FI-CL system were investigated and optimized. Under the optimal conditions, the relative CL intensity was linear with the captopril concentration in the range of 0.3-15.0 μg/mL. The detection limit for captopril was 0.05 μg/mL, and the relative standard deviation (n=11) was 2.0% for 5.0 μg/mL captopril. The proposed method was applied to the analysis of captopril in tablet and human urine with the recoveries of 83.1%-112.5%, and the relative standard deviations of 0.5%-4.4%. The results obtained by the proposed method agreed well with those obtained from HPLC method. The proposed method is fast, convenient, and cost-effective for the determination of captopril in medicine and biological samples.

Sensitivity, Prediction Uncertainty, and Detection Limit for Artificial Neural Network Calibrations

With the proliferation of multivariate calibration methods based on artificial neural networks, expressions for the estimation of figures of merit such as sensitivity, prediction uncertainty, and detection limit are urgently needed. This would bring nonlinear multivariate calibration methodologies to the same status as the linear counterparts in terms of comparability. Currently only the average prediction error or the ratio of performance to deviation for a test sample set is employed to characterize and promote neural network calibrations. It is clear that additional information is required. We report for the first time expressions that easily allow one to compute three relevant figures: (1) the sensitivity, which turns out to be sample-dependent, as expected, (2) the prediction uncertainty, and (3) the detection limit. The approach resembles that employed for linear multivariate calibration, i.e., partial least-squares regression, specifically adapted to neural network calibration scenarios. As usual, both simulated and real (near-infrared) spectral data sets serve to illustrate the proposal.

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

A simple, rapid, and selective HPLC-UV method was developed for the determination of antihypertensive drug substances: amlodipine besilat (AML), olmesartan medoxomil (OLM), valsartan (VAL), and hydrochlorothiazide (HCT) in pharmaceuticals and plasma. These substances are mostly used as combinations. The combinations are found in various forms, especially in current pharmaceuticals as threesome components: OLM, AML, and HCT (combination I) and AML, VAL, and HCT (combination II). The separation was achieved by using an RP-CN column, and acetonitrile-methanol-10 mmol orthophosphoric acid pH 2.5 (7 : 13 : 80, v/v/v) was used as a mobile phase; the detector wavelength was set at 235 nm. The linear ranges were found as 0.1-18.5  μ g/mL, 0.4-25.6  μ g/mL, 0.3-15.5  μ g/mL, and 0.3-22  μ g/mL for AML, OLM, VAL, and HCT, respectively. In order to check the selectivity of the method for pharmaceutical preparations, forced degradation studies were carried out. According to the validation studies, the developed method was found to be reproducible and accurate as shown by RSD ≤6.1%, 5.7%, 6.9%, and 4.6% and relative mean error (RME) ≤10.6%, 5.8%, 6.5%, and 6.8% for AML, OLM, VAL, and HCT, respectively. Consequently, the method was applied to the analysis of tablets and plasma of the patients using drugs including those substances.

Spectral characteristic investigation on complex of Ni (II) with captopril and its analytical application

In this paper, Ni (II) reacting with captopril (CPT) can form complex in alkaline solution and the formed complex has a characteristic absorption peak at 340nm. The absorbance of the Ni-CPT complex increases linearly with the increased concentration of captopril. The study also shows that ammonia has an obvious sensitizing effect on the absorbance. Based on the study, a new method for the determination of captopril is established. Experimental results show that the linear range of this method under optimum condition is 1.0-60mg/L with correlation coefficient, detection limit and precision of 0.9999, 0.31mg/L and 0.87%, respectively. The method used to determine captopril in commercial captopril tablets has a satisfactory result with the recoveries in the range of 99.0-103.6% and the relative standard deviation (RSD) in the range of 0.8-3.7%. We preliminarily study the reaction mechanism and demonstrate that the complex ratio of Ni (II) with captopril is 1:2 and the formation constant is 6.3×10(9).