Two reproducible and sensitive liquid chromatographic methods to quantify atenolol and propranolol in human plasma and determination of their associated analytical error functions

Direct doping analysis of beta-blocker drugs from urinary samples by on-line molecularly imprinted solid-phase extraction coupled to liquid chromatography/mass spectrometry

The hydrophilic layer forms hydrogen bonds with water, minimizing the interference of this solvent in the analyte–polymer complex.

On-line coupling of sequential injection extraction with restricted-access materials and post-column derivatization for sample clean-up and determination of propranolol in human plasma

The presented paper deals with a new methodology for direct determination of propranolol in human plasma. The methodology described is based on sequential injection analysis technique (SIA) coupled with solid phase extraction (SPE) column based on restricted access materials (RAM). Special RAM column containing 30 microm polymeric material-N-vinylacetamide copolymer was integrated into the sequential injection manifold. SIA-RAM system was used for selective retention of propranolol, while the plasma matrix components were eluted with two weak organic solutions to waste. Due to the acid-basic and polarity properties of propranolol molecule and principles of reversed-phase chromatography, it was possible to retain propranolol on the N-vinylacetamide copolymer sorbent (Shodex MSpak PK-2A 30 microm (2 mm x 10 mm)). Centrifuged plasma samples were aspirated into the system and loaded onto the column using acetonitrile-water (5:95, v/v), pH 11.00, adjusted by triethylamine. The analyte was retained on the column while proteins contained in the sample were removed to waste. Interfering endogenous substances complicating detection were washed out by acetonitrile-water (15:85), pH 11.00 in the next step. The extracted analyte was eluted by means of tetrahydrofuran-water (25:75), pH 11.00 to the fluorescence detector (emission filter 385 nm). The whole procedure comprising sample pre-treatment, analyte detection and column reconditioning took about 15 min. The recoveries of propranolol from undiluted plasma were in the range 96.2-97.8% for three concentration levels of analyte. The proposed SIA-RAM method has been applied for direct determination of propranolol in human plasma.

Determination of atenolol by the micelle-stabilized room-temperature phosphorescence methodology

A micellar-stabilized room-temperature phosphorescence (MS-RTP) method for the determination of atenolol has been developed in micellar solutions of sodium dodecylsulphate (SDS) in the presence of thallium(I) as a heavy atom and sodium sulphite as an oxygen scavenger. The effects of thallium(I) nitrate, SDS and sodium sulphite concentrations on atenolol MS-RTP intensity were studied. Optimized conditions to obtain maximum sensitivity were 0.015 mol/L thallium(I) nitrate, 0.1 mol/L SDS and 0.0075 mol/L sodium sulphite. The maximum phosphorescence signal was completely developed in 10 min and the intensity was measured at lambda(ex) = 272 nm and lambda(em) = 412 nm. The linear range of application obtained was 2.01-16.00 microg/mL. The detection limit estimated from the least-squares regression analysis was 0.86 microg/mL and the relative standard deviation of 10 replicates was 1.7%. The proposed method was applied to the determination of atenolol in a pharmaceutical formulation. The quantitation was carried out by means of standard calibration, standard-additions calibration and Youden calibration. These three experiments were necessary to evaluate the presence of constant and proportional errors due to the matrix.

A Micromethod for the Quantification of Atenolol in Plasma Using High-Performance Liquid Chromatography With Fluorescence Detection

A simple, rapid, selective, and sensitive analytical method was developed for the quantification of atenolol in small volumes of plasma, by high-performance liquid chromatography with fluorescence detection. Only 200 microL of plasma was used for chromatographic analysis. Separation was performed on a C18 reverse-phase column (4 microm) using a binary mobile phase consisting of 0.05 M of phosphate buffer, pH 5.5, and methanol (80:20, vol/vol) at a flow rate of 0.7 mL/minute. The retention times of atenolol and of the internal standard (sotalol) were 12.7 and 10.4 minutes, respectively. Validation of this analytical method showed a good linear correlation (8-2000 ng/mL), high sensitivity (quantification limit: 8 ng/ml and detection limit: 4 ng/mL), accuracy of 99.3%, and intraday and interday precision of 5.3% and 6.9%, respectively. Absolute recovery was 93.7%. The method was found to be robust, with acceptable stability. The analytical method was validated by the quantification of atenolol in plasma obtained from 2 patients with unstable angina, scheduled for myocardium revascularization surgery, who were chronically treated with 50 mg of atenolol administered per os once a day. The method developed was found to be adequate for use in pharmacokinetic studies and in adjusted dose pharmacotherapy.

A simple spectrophotometric method for the determination of β-blockers in dosage forms

A simple, extraction-free spectrophotometric method is proposed for the analysis of some beta-blockers, namely atenolol, timolol and nadolol. The method is based on the interaction of the drugs in chloroform with 0.1% chloroformic solutions of acidic sulphophthalein dyes to form stable, yellow-coloured, ion-pair complexes peaking at 415 nm. The dyes used were bromophenol blue (BPB), bromothymol blue (BTB) and bromocresol purple (BCP). Under the optimum conditions, the three drugs could be assayed in the concentration range 1-10 microg ml(-1) with correlation coefficient (n = 5) more than 0.999 in all cases. The stoichiometry of the reaction was found to be 1:1 in all cases and the conditional stability constant (K(F)) of the complexes have been calculated. The free energy changes (DeltaG) were determined for all complexes formed. The interference likely to be introduced from co-formulated drugs was studied and their tolerance limits were determined. The proposed method was then applied to dosage-forms the percentage recoveries ranges from 99.12-100.95, and the results obtained were compared favorably with those given with the official methods.

High operationally stable sol-gel diglycidyloxycalix[4]arene fiber for solid-phase microextraction of propranolol in human urine

A simple, sensitive, and accurate method for the determination of propranolol in human urine has been developed based on solid-phase microextraction (SPME) followed by GC-flame ionization detection (FID). The sol-gel 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix[4]arene/hydroxy-terminated silicone oil (diglycidyloxy-C[4]/OH-TSO) fiber was prepared to accommodate to the harsh extraction conditions. It possesses excellent alkali-proof ability and retains its extraction characteristics intact even after treatment with highly alkaline (4 mol/L) NaOH solution. Direct chemical bonding of the coating to the fiber surface provides it with excellent solvent resistance and the introduction of calixarene enhances its thermal stability. The newly developed sol-gel calixarene coating was effectively used for the extraction of propranolol in human urine. No interference with the determination of propranolol was observed from the urine components. Standard curves were linear in the range 50-5000 microg/L for headspace-SPME (HS-SPME) and 25-25000 microg/L for direct-SPME (Dir-SPME) with correlation coefficients better than 0.9999. The detection limit was 0.275 microg/L for HS-SPME and 0.193 microg/L for Dir-SPME. The method was validated using standard addition methodology and recovery values were between 91.4 and 117% for both the sampling modes with the RSDs less than 6% at different concentration levels in the linear ranges. The results obtained by both the sampling modes were feasible, and no significant differences between them regarding accuracy, precision, and detection limits were seen.

Human bioavailability of propranolol from a matrix-in-cylinder system with a HPMC-Gelucire® core

The bioavailability of propranolol from a matrix-in-cylinder system for sustained drug delivery, consisting of a hot-melt extruded ethylcellulose pipe surrounding a drug-containing HPMC-Gelucire 44/14 core, was determined. An oral dose of 80 mg propranolol hydrochloride was administered to healthy volunteers (n = 10) in a randomized cross-over study design either as a commercial pellet formulation (Inderal retard mitis) or as a matrix-in-cylinder system. The influence of concomitant food intake on drug release from the matrix-in-cylinder system was also studied. During the first 10 h after administration, the matrix-in-cylinder system resulted in similar plasma levels as the reference formulation Inderal. The concomitant intake of a high-fat, high-calorie breakfast did not cause dose-dumping. Between 10 h and 24 h after administration of the matrix-in-cylinder system, a remarkable increase of the propranolol plasma levels was noticed (compared to Inderal). This effect was even more pronounced under fed conditions. The matrix-in-cylinder system had a relative bioavailability of 156% (fasted conditions) and 222% (fed conditions) compared to the marketed reference product. In order to elucidate the origin of this increased bioavailability, Caco-2 experiments and dog lymph studies were performed. However, none of these experiments was able to provide a conclusive answer.

Spectrophotometric determination of propranolol in formulations via oxidative coupling with 3-methylbenzothiazoline-2-one hydrazone

A simple spectrophotometric method has been developed for the determination of propranolol hydrochloride in pure as well as in dosage forms. The method is based on the oxidative coupling reaction with 3-methylbenzothiazoline-2-one hydrazone. A mixture of an acidic solution of the chromogenic agent and the drug upon treatment with ceric ammonium sulfate produces an orange color peaking at 496 nm. The absorbance-calibration plot was linear over the range 1-10 microg/ml with minimum detectability (S/N=2) of 0.1 microg/ml (3.38x10(-7) M). The molar absorbitivity was 3.195x10(3) l/M/cm with correlation coefficient (n=10) of 0.9999. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was applied successfully to the determination of propranolol in its dosage forms. A proposal of the reaction pathway was presented.

A sensitive fluorescence optosensor for analysing propranolol in pharmaceutical preparations and a test for its control in urine in sport

We describe a simple and selective method for analysing propranolol and a sensitive test for its control in urine. A flow-through fluorescence optosensor based on on-line immobilization in a non-ionic-exchanger (Amberlite XAD-7) solid support in a continuous flow was used in both cases. Determination was made in 5 mM H(2)PO(4)(-)/HPO(4)(2-) buffer solution at pH 6 at a working temperature of 20 degrees C. Fluorescence intensities were measured at lambda(ex/em) = 300/338 nm with a response time of 80 s, thus obtaining a linear concentration range of between 0 and 250.0 ng ml(-1) with a detection limit of 1.3 ng ml(-1), an analytical sensitivity of 6.0 ng ml(-1) and a standard deviation of 2.40% at a 150 ng ml(-1) concentration level for propranolol. We also propose a test to detect propranolol in urine with a linear concentration range between 0 and 100.0 ng ml(-1), a detection limit of 0.2 ng ml(-1), an analytical sensitivity of 1.0 ng ml(-1), and a standard deviation of 0.84% at a 75 ng ml(-1) concentration level. The effect of proteins presents in urine samples were evaluated. The two proposed methods were satisfactorily applied to commercial formulations and urine samples respectively.

Development, validation and analytical error function of two chromatographic methods with fluorimetric detection for the determination of bisoprolol and metoprolol in human plasma

This work describes two high-performance liquid chromatographic methods for the individual determination of bisoprolol and metoprolol in human plasma. Analytical methods involve two different liquid-liquid extractions of human plasma, with diethyl ether for bisoprolol and with dichloromethane for metoprolol, coupled with a similar Nucleosil C(18) reversed-phase HPLC column. Fluorimetric detection was used to identify both beta-blockers. Retention times for bisoprolol and metoprolol were 8.7 and 3.2 min, respectively. Linear regressions for the calibration curves were linear at a concentration range of 6.25-200 ng/mL. Intra- and inter-day precision coefficients of variations and accuracy bias were acceptable (within 15%) over the entire range for both drugs. Average recovery was 89% for metoprolol and 98% for bisoprolol. Once the methods had been validated, analytical error functions were established as standard deviation (SD; ng/mL) = 2.216 + 3.608 x 10(-4)C(2) (C = theoretical concentration value) and SD-(ng/mL) = 0.408 + 0.378 x 10(-1)C for bisoprolol and metoprolol, respectively. The methods developed and their associated analytical error functions will be suitable for pharmacokinetic studies and for determination of plasma concentration if posology individualization of these drugs is needed.

Studies on properties and application of non-protected room temperature phosphorescence of propranolol

A direct and simple non-protected room temperature phosphorimetry (NP-RTP) for determine propranolol, which using I- as a heavy atom perturber and sodium sulfite as a deoxygenator, has been developed. The phosphorescence peak wavelength maxima lambda(ex)/lambda(em) = 288/494, 522 nm. The analytical curve of propranolol gives a linear dynamic range of 8.0 x 10(-8)-2.0 x 10(-5) mol l(-1) and a detection limit of 3 x 10(-8) mol l(-1). The influence of I- concentration on RTP lifetime of propranolol was studied and the luminescence kinetic parameters were calculated. It is found that the relation between I- concentration (x) and RTP lifetime (tau) can be expressed as tau = 1.25e(-0.477x) and the rate constants of phosphorescence emission k(p) was 0.800 per ms. The method was applied directly to determination of propranolol in urine and drug tablets with a satisfactory result. The recoveries were 96.6-97.4% and the relative standard deviation was 2% for the 1.00 x 10(-6)-4.00 x 10(-6) mol l(-1) propranolol in spiked urine sample.