A Versatile Stability-indicating Liquid Chromatographic Method for the Simultaneous Determination of Atenolol, Hydrochlorothiazide and Chlorthalidone

Background:

Atenolol is a selective beta 1 blocker that can be used alone or in combination with hydrochlorothiazide or with chlorthalidone for the treatment of hypertension and prevention from a heart attack.

Objective:

The main target of this work was to improve modern, easy, accurate and selective liquid chromatographic method (RP-HPLC) for the determination of these drugs in the presence of their degradation products. These methods can be used as analytical gadgets in quality control laboratories for a routine examination.

Methods:

In this method, the separation was accomplished through an Inertsil® ODS-3V C18 column (250 mm x 4.6 mm, 5 μm), the mobile phase used was 25 mM aqueous potassium dihydrogen orthophosphate solution adjusted to pH 6.8 by using 0.1M sodium hydroxide and acetonitrile (77 : 23, v/v), the flow rate used was 1 ml/min and detection was achieved at 235 nm using UV.

Results:

All peaks were sharp and well separated, the retention times were atenolol degradation (ATN Deg.) 2.311 min, atenolol (ATN) 2.580 min, hydrochlorothiazide degradation (HCT Deg.) 5.890 min, hydrochlorothiazide (HCT) 7.016 min, chlorthalidone degradation CTD Deg 8.018 min and chlorthalidone (CTD) 14.972 min. Linearity was obtained and the range of concentrations was 20- 160 μg/ml for atenolol, 10-80 μg/ml for hydrochlorothiazide and 10-80 μg/ml for chlorthalidone. According to ICH guidelines, method validation was accomplished, these methods include linearity, accuracy, selectivity, precision and robustness.

Conclusion:

The optimized method demonstrated to be specific, robust and accurate for the quality control of the cited drugs in pharmaceutical dosage forms.

Comparative study and multiple linear regression analysis for assessment of chromatographic behavior of structurally related β-blockers on different stationary phases

A quantitative structure-retention relationship study was performed by thin layer chromatography on a number of β-blockers using 315 molecular descriptors of which nine were selected to be having the most important physicochemical properties. These descriptors provide good correlations with chromatographic behavior of the studied structurally related drugs. This research was completed on three pretreated silica gel plates via impregnation in urea, sodium dodecyl sulfate, and dimethylformamide, hence it possesses varying interplay mechanisms and polarities. The retention parameters were obtained by utilizing four solvent systems of two additives of variable ratios, consequently specific polarities in addition to imparted different pH values using either glacial acetic acid or liquid ammonia. Calculated theoretical approaches prove good correlations between investigated descriptors and retention factors. Some correlations show excellent predicting models, which might be critical for toning better know-how relationships between chemical structures and retention of β-blockers.

Sensitive spectrophotometric determination of atenolol in pharmaceutical formulations using bromate-bromide mixture as an eco-friendly brominating agent

Three simple and sensitive spectrophotometric methods are proposed for the determination of atenolol (ATN) in bulk drug and tablets. The methods are based on the bromination of ATN by the bromine generated in situ by the action of the acid on the bromate-bromide mixture followed by the determination of unreacted bromine by reacting with a fixed amount of either meta-cresol purple (MCP) and measuring the absorbance at 540 nm (method A) and 445 nm (method B) or erioglaucine (EGC) and measuring the absorbance at 630 nm (method C). Beer's law is valid within the concentration ranges of 1.0-20.0, 2.0-40.0 and 1.0-8.0 μg/mL for method A, method B and method C, respectively. The calculated molar absorptivities were found to be 1.20×10(4), 4.51×10(3) and 3.46 × 10(4)  L/mol · cm for method A, method B and method C, respectively. Sandell's sensitivity values, correlation coefficients, limits of detection and quantification are also reported. Recovery results were statistically compared with those of a reference method by applying Student's t- and F-test. The novelty of the present study is the measurement of two different colors using MCP, that is, red-pink color of MCP in acid medium at 540 nm and yellowish-orange color of brominated MCP at 445 nm.

Determination of atenolol in pharmaceutical formulations by diffuse reflectance spectroscopy

A simple analytical method for quantification of atenolol in pharmaceutical formulations by diffuse reflectance spectroscopy is described. The method is based on the reaction, on the filter paper surface, between the drug and p-chloranil producing a colored compound. The best reaction conditions were obtained with 20 µL of atenolol solution and 20 µL of p-chloranil. All reflectance measurements were carried out at 550 nm and the linear range was from 1.13x10-2 to 7.88x10-2 mol L-1 (r = 0.9992). The limit of detection was 2.80 x 10-3 mol L-1. The proposed method was successfully applied to analysis of different commercial brands of pharmaceutical formulations and the results obtained by the proposed method were in good agreement with those obtained using the British Pharmacopoeia method.

Colorimetric determination of beta-blockers in pharmaceutical formulations

A simple, accurate, precise and sensitive colorimetric method for the determination of some beta-blockers as atenolol (Ateno), metoprolol (Metop), sotalol (Sot) and nadolol (Nad) is described. This method is based on the formation of charge transfer complex with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in methanolic-aqueous (for Ateno and Metop) or acetone-aqueous (for Sot and Nad) medium [30% (v/v)]. The orange color products are measured at 485, 470, 465 and 462 nm for Ateno, Metop, Sot and Nad, respectively. The optimization of various experimental conditions is described. Beer's law is obeyed in the range 0.4-60 microgram ml(-1) while that obtained applying Ringbom is 0.8-56 microgram ml(-1). The molar absorptivity, Sandell sensitivity, detection and quantification limits are calculated. The results obtained showed good recoveries of 99.5+/-1.1, 100.3+/-1.2, 100.5+/-1.0 and 99.3+/-1.1% with relative standard deviations of 0.74, 0.98, 1.15 and 0.87% for Ateno, Metop, Sot and Nad, respectively. Applications of the proposed method to representative pharmaceutical formulations are successfully presented.

HPTLC determination of ketorolac tromethamine

A High Performance Thin Layer Chromatography (HPTLC) method for quantification of ketorolac tromethamine, a non-narcotic and non-steroidal agent was developed. The mobile phase composition was chloroform-ethyl acetate-glacial acetic acid (3:8:0.1, v/v/v). Spectrodensitometric analysis of ketorolac tromethamine was carried out at 323 nm. The calibration curve was linear in the range of 200-700 ng. The mean values of slope, intercept and correlation coefficient were, 2941, 749583, 0.99. The method was validated for method precision, system precision, marketed sample analysis and recovery studies. The % CV for method precision studies was 1.98 (n = 6) and system precision study was 1.83 (n = 6). The average recovery was found to be 99.2%. Acid and base degraded products were adequately separated from the drug. The method was successfully used for the determination of drug from saliva. The results indicate that the method is simple, specific, selective and reliable for quantitative analysis of ketorolac tromethamine as bulk drug and from formulations. It can also be applied for the stability study of the drug and analysis of drug in biological fluids.