Determination of some beta-blockers as dabsyl derivatives by HPLC

Application of UHPLC-QqQ-MS/MS Method for Quantification of Beta-Adrenergic Blocking Agents (β-Blockers) in Human Postmortem Specimens

Betablockers are one of the most frequently used medications in cardiology. They can lead to fatal drops in blood pressure and heart rhythm disturbances. Death is functional, and poisoning with this group of drugs can be difficult to detect. The liquid-liquid extraction (LLE) method developed using ethyl acetate at pH 9 successfully identified 18 β-blockers in human blood. The method's limit of quantification (LOQ) was in the range of 0.1 to 0.5 ng/mL. No carryover of substances between samples was detected, and no interfering ion current signals were observed in the biological samples at the retention times of the compounds or internal standards. All compounds had a coefficient of determination (R2) above 0.995. Intraday and interday precision (RSD%) and accuracy (RE%) for low and high QC levels were within 1.7-12.3% and -14.4 to 14.1%, respectively. Very good recovery (80.0-119.6%) and matrix effect (±20.0%) values were achieved for all compounds. In addition, fragmentation spectra were collected for all the examined substances, and high-resolution spectra were presented for landiolol and metipranolol, because they are not available in commercial HRMS spectra databases. The developed method was applied in authentic postmortem samples.

Spectrofluorimetric Determination of Drugs Containing Active Methylene Group Using N1-Methyl Nicotinamide Chloride as a Fluorigenic Agent

A spectrofluorimetric method was described for the determination of drugs containing active methylene groups adjacent to carbonyl groups. The method was applied successfully to the determination of three life saving cardiovascular drugs, with narrow therapeutic indices: pentoxifylline (I), propafenone hydrochloride (II) and acebutolol hydrochloride (III), in laboratory-prepared mixtures, in commercial tablets and in plasma samples. The method involved the reaction of each of the tested drugs with N1-methyl nicotinamide chloride (NMNCl) in the presence of alkali, followed by addition of formic acid, where highly fluorescent reaction products were produced. The produced fluorescence were measured quantitatively at 472 nm (lambdaex 352 nm), 409 nm (lambdaex 310 nm) and 451 nm (lambdaex 266 nm) for (I), (II), and (III) respectively. The method was linear over concentration ranges of 10-1000 microg/ml , 0.2-12 microg/ml and 0.08-10 microg/ml in standard solutions for (I), (II), and (III) respectively. In spiked human plasma samples, calibration graphs were linear over concentration ranges of 20-1000 microg/ml, 0.2-15 microg/ml and 0.08-10 microg/ml for (I), (II), and (III) respectively. The method showed good accuracy, specificity and precision in both laboratory-prepared mixtures and spiked human plasma samples. The proposed method is simple, with low instrumentation requirements, suitable for quality control application, bioavailability and bioequivalency studies.

Spectrophotometric determination of some beta-blockers in dosage forms based on complex formation with Cu(II) and Co(II)

Four sensitive and accurate spectrophotometric methods have been developed for the assay of Acebutolol Hydrochloride (ACH), Atenolol (ATE) and Propranolol Hydrochloride (PRH), which are based on the complexation of drugs with copper(II) (Cu(II)) and cobalt(II) (Co(II)). The coloured products are measured at 613, 694, 548 and 614 nm for ACH-Co(II), ATE-Cu(II), PRH-Cu(II) and PRH-Co(II) method, respectively. The optimization of various experimental conditions is described. Conformity with Beer's Law was evident over a concentration range in the of 2 x 10(-5) - 1 x 10(-2) mol/L. The molar absorptivity, detection and quantification limits are calculated. The results obtained showed good recoveries of 100.2 +/- 1.1, 100.3 +/- 1.2, 100.75 +/- 1.0 and 99.55 +/- 1.1 % with relative standard deviations of 0.410, 0.490, 0.161 and 0.140 % for ACH-Co(II), ATE-Cu(II), PRH-Cu(II) and PRH-Co(II) method, respectively. They were applied to the analysis of tablet forms of the drugs and the results were statistically compared with those obtained by official and literature methods using t- and F-tests. There were no significant difference among the mean values and precisions of the methods at 95% confidence level.

First derivative spectrophotometric, TLC-densitometric, and HPLC determination of acebutolol HCL in presence of its acid-induced degradation product

Three methods are presented for the determination of acebutolol HCl in presence of its acid-induced degradation product. The first method was based on measurement of the first derivative amplitude of acebutolol HCl at 266.6 nm. The second method was based on separation of acebutolol HCl from its acid-induced degradation product followed by densitometric measurement of the spots at 230 nm. The separation was carried out on silica gel 60 F254, using ethanol-glacial acetic acid (4:1, v/v) as mobile phase. Second order polynomial equation was used for the regression line. The third method was based on high performance liquid chromatographic (HPLC) separation of acebutolol HCl from its acid-induced degradation product on a reversed phase, ODS column using a mobile phase of methanol-water (55:45, v/v) with UV detection at 240 nm. The first derivative spectrophotometric method was utilized to investigate the kinetics of the acid degradation process at different temperatures.

Automated in-tube solid-phase microextraction coupled with liquid chromatography/electrospray ionization mass spectrometry for the determination of beta-blockers and metabolites in urine and serum samples

The technique of automated in-tube solid-phase microextraction (SPME) coupled with liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) was evaluated for the determination of beta-blockers in urine and serum samples. In-tube SPME is an extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. LC/MS analyses of beta-blockers were initially performed by liquid injection onto a LC column. Nine beta-blockers tested in this study gave very simple ESI mass spectra, and strong signals corresponding to [M + H]+ were observed for all beta-blockers. The beta-blockers were separated with a Hypersil BDS C18 column using acetonitrile/methanol/water/acetic acid (15:15:70:1) as a mobile phase. To optimize the extraction of beta-blockers, several in-tube SPME parameters were examined. The optimum extraction conditions were 15 draw/eject cycles of 30 microL of sample in 100 mM Tris-HCl (pH 8.5) at a flow rate of 100 microL/min using an Omegawax 250 capillary (Supelco, Bellefonte, PA). The beta-blockers extracted by the capillary were easily desorbed by mobile-phase flow, and carryover of beta-blockers was not observed. Using in-tube SPME/LC/ESI-MS with selected ion monitoring, the calibration curves of beta-blockers were linear in the range from 2 to 100 ng/mL with correlation coefficients above 0.9982 (n = 18) and detection limits (S/N = 3) of 0.1-1.2 ng/mL. This method was successfully applied to the analysis of biological samples without interference peaks. The recoveries of beta-blockers spiked into human urine and serum samples were above 84 and 71%, respectively. A serum sample from a patient administrated propranolol was analyzed using this method and both propranolol and its metabolites were detected.

Analysis of nifedipine-acebutolol hydrochloride binary combination in tablets using UV-derivative spectroscopy, capillary gas chromatography and high performance liquid chromatography

Three methods are described for the simultaneous determination of nifedipine and acebutolol hydrochloride in combined pharmaceutical tablets. The first method depends on first-derivative ultraviolet spectrophotometry, with peak-to-base and zero-crossing measurements methods. The first derivative amplitudes at 400 and 352 nm were selected for the assay of nifedipine and acebutolol hydrochloride, respectively. Calibration graphs follow Beer's law in the range of 4-12 and 44-132 micrograms ml-1 and the linearity was satisfactory (r = 0.999) for nifedipine and acebutolol hydrochloride, respectively. The second method was based on the separation of nifedipine from acebutolol hydrochloride, with an internal standard thymolphthalein, using capillary gas-liquid chromatography with a programmable temperature change. The third method was based on high performance liquid chromatographic separation of the two drugs on a reversed-phase, C18, column using a mobile phase of methanol-water (55:45, pH 4.5) with a programmable flow rate of 1 ml min-1 for 4 min which changed to 2 ml min-1 for the rest of the run. The detection was done at 260 nm using oxprenolol hydrochloride as an internal standard. Both chromatographic methods showed good linearity, precision and reproducibility. No spectral or chromatographic interference from the tablet excipients were found. The proposed methods were successfully applied to the assay of commercial tablets and a content uniformity test. The procedures were rapid, simple nondestructive and suitable for quality control application.