Study of enantioseparation of ß-blockers using amylose tris(3-chloro-5-methylphenylcarbamate) as chiral stationary phase under polar-organic, reversed-phase and hydrophilic interaction liquid chromatography conditions.

In this study, we describe the experimental variables influencing enantioseparation of twelve ß-blockers when analyzed under polar-organic, reversed-phase and hydrophilic interaction liquid chromatography conditions on a column with immobilized amylose tris(3-chloro-5-methylphenylcarbamate) as chiral stationary phase. Regarding polar-organic mode, two component mobile phases consisting of methanol, ethanol or acetonitrile with the addition of basic additives such as diethylamine, triethylamine, mono-ethanolamine, ethylendiamine or trifluoroacetic acid/diethylamine mixture were evaluated. Studies of retention at different temperatures were also performed. In reversed-phase mode, mixtures consisting of methanol or acetonitrile with either aqueous boric acid-borate buffer or sodium hydrogen carbonate-carbonate buffer solutions were compared aiming to study the influence of organic modifier as well as buffer type and pH on resolution. In addition, a systematic evaluation of the retention factors of ß-blockers enantiomers in hydro-organic eluents containing acetonitrile in presence of diethylamine as additive was carried out by increasing progressively the water content, in order to check for retention dependencies indicative of the interplay of both hydrophilic interaction liquid chromatography and reversed-phase modes.

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 use of beta-blockers to enhance performance in some sports is forbidden. Based on this regulation, there is a demand for dynamic analytical procedures for analyzing these compounds quickly and without manual sample preparation. Therefore, the use of a molecularly imprinted polymer (MIP) in a multidimensional liquid chromatographic system coupled to a mass spectrometer provides a good alternative for improving the selectivity and practicality of the beta-blocker analyses, as described in this paper. A water-compatible MIP for oxprenolol was synthesized by the precipitation method, using methacrylic acid as a functional monomer and 2-hydroxyethyl methacrylate and glycerol dimethacrylate as hydrophilic monomers. A column filled with MIP was coupled to an LC-MS/MS instrument under the multidimensional configuration, with 10.0 mmol L(-1) ammonium formate buffer (pH 5.0) as the loading and reconditioning mobile phase and a 0.01% formic acid aqueous solution-methanol (30 : 70 v : v) as the elution mobile phase. The system was used for on-line extraction and quantization of oxprenolol (from 1.0 to 75.0 µg L(-1)), atenolol, propranolol, nadolol, pindolol, labetalol and metoprolol (all from 3.0 to 50 µg L(-1)) simultaneously, from urine samples. The correlation coefficient was higher than 0.99 for all the analytes. Suitable precision and accuracy were obtained.

Oxidation-coagulation of ß-blockers by K2FeVIO4 in hospital wastewater: assessment of degradation products and biodegradability.

This study investigated the degradation of atenolol, metoprolol and propranolol beta-blockers by ferrate (K2FeO4) in hospital wastewater and in aqueous solution. In the case of hospital wastewater, the effect of the independent variables pH and [Fe(VI)] was evaluated by means of response surface methodology. The results showed that Fe(VI) plays an important role in the oxidation-coagulation process, and the treatment of the hospital wastewater led to degradations above 90% for all the three ß-blockers, and to reductions of aromaticity that were close to 60%. In addition, only 17% of the organic load was removed. In aqueous solution, the degradation of the ß-blockers atenolol, metoprolol and propranolol was 71.7%, 24.7% and 96.5%, respectively, when a ratio of 1:10 [ß-blocker]:[Fe(VI)] was used. No mineralization was achieved, which suggests that there was a conversion of the ß-blockers to degradation products identified by liquid chromatography/mass spectrometry tandem. Degradation pathways were proposed, which took account of the role of Fe(VI). Furthermore, the ready biodegradability of the post-process samples was evaluated by using the closed bottle test, and showed an increase in biodegradability. The use of the ferrate advanced oxidation technology seems to be a useful means of ensuring the remediation of hospital and similar wastewater.

Evaluation of carbon nanotubes as chiral selectors for continuous-flow enantiomeric separation of carvedilol with fluorescent detection.

Single-walled carbon nanotubes (SWNT) are proposed as chiral selectors for separation of carvedilol stereoisomers beginning since its racemic mixture. The novel developed FIA-methodology employs a microcolumn (mC) packed with a few milligrams of SWNT which showed to be effective in S(-) and R(+) carvedilol separation. Attending to spectral properties of analytes, molecular fluorescence was employed in the detection step. Separation of carvedilol enantiomers was achieved in less than 70s with an acceptable resolution factor of 3.16. Variables that influence the chiral separation such as pH and composition of eluent solution, sample injection volume and flow rate, activation mode of NTs and mass of the same in column have been examined in detail. At optimal operational conditions, well repeatability was achieved using the same column for more than 100 injections, putting in evidence the stability of nanomaterial and the efficacy and versatility of the proposed FIA-configuration. The new methodology was successfully applied to S(-) and R(+) carvedilol quantification in pharmaceutical preparations, resulting an attractive alternative to traditional separative methods being fast, simple, using low cost instrumentation and producing scarce waste.

New mucoadhesive chitosan film for ophthalmic drug delivery of timolol maleate: in vivo evaluation.

PURPOSE: Chitosan, a cationic polysaccharide biopolymer with mucoadhesive properties, presents a promising future in the prolonged ocular delivery of drugs. The present study compared the efficacy and safety of chitosan-coated timolol maleate (TM) mucoadhesive film, using a 0.5% TM commercial ophthalmic solution in a rabbit model. In addition, this study investigates the maximum release time of these implants in vivo. METHODS: The mucoadhesive films were prepared by means of a casting and solvent evaporation technique performed in a 2 wt% acetic acid solution and distilled water. Physical properties were characterized by release and swelling studies, differential scanning calorimetry, and attenuated total reflectance fourier transformed infrared spectroscopy (ATR-FTIR). The developed formulations were evaluated for their pharmacodynamics in ocular normotensive albino rabbits, in which the intraocular pressure (IOP) was measured by means of applanation tonometer on alternative days (13 h) for 11 weeks. For 15 days, 0.5% TM commercial ophthalmic solution was administered twice a day (n=5) and compared to chitosan-coated TM (n=5). In the control group (n=5), saline was used twice a day. The maximum TM release time from chitosan films were also recorded. After euthanasia, the right eyes were removed from the 3 groups for histological analyses. RESULTS: In an in vitro study, TM was released over a 4-week period, in which 85% of the drug was released over the first 2 weeks. However, the film's release of TM lowered the in vivo IOP levels over a 10-week period. No significant difference in the lowering of IOP in rabbits treated with 0.5% TM commercial ophthalmic solution, as compared to those that received the films (P<0.05), could be observed. No signs of ocular discomfort or irritations could be identified upon ophthalmic examination by slit-lamp biomicroscopy. Ophthalmic structures that came in direct contact with the films revealed no alterations within the histopathological studies. Moreover, the animals showed no signs of ocular discomfort during the experimental assays. CONCLUSION: These findings suggest that the TM-loaded chitosan film is safe and efficient and presents a promising future as an ocular drug delivery system in the treatment and prevention of glaucoma.

Isquemia miocárdica investigada com ecocardiografia sob estresse físico em pacientes com incompetência cronotrópica em uso de betabloqueador / Myocardial ischemia during exercise echocardiography in patients with chronotropic incompetence in use of beta blockers

Introdução: Objetivo: Avaliar a influência da utilização de betabloqueador em pacientes com incompetência cronotrópica, submetidos à Ecocardiografia sob Estresse. Método: Estudo observacional, transversal e retrospectivo, realizado entre janeiro/2001 e outubro/2008. Após exclusão de pacientes com precordialgia típica, com doença arterial coronariana estabelecida e que não usavam betabloqueador, foram avaliados 635 pacientes que faziam uso regular desta droga, suspensa 3 dias antes da execução do exame. A amostra foi dividida em 2 grupos: G1 e G2 (com e sem incompetência cronotrópica), que foram comparados quanto à características clínicas, hemodinâmicas, eletrocardiográficas e ecocardiográficas . Resultados: O G1 constituiu-se de 81 pacientes (13 por cento); o G2 de 554 pacientes (87 por cento). Quanto às características, os pacientes do G1 eram idosos (p=0,002), apresentavam mais precordialgia atípica (p=0,013, mais dispnéia durante o exame (p=0,001) e eram sintomáticos (p=0,009). Do ponto de vista ecocardiográfico, não foi possível diferenciar os dois grupos, quanto ao diagnóstico de isquemia miocárdica induzida pelo esforço (p=0,140) e, também quanto ao índice de escore de motilidade do ventrículo esquerdo durante o exercício (p=0,223). Todavia, G1 demonstrou maior índice de massa do ventrículo esquerdo (p=0,001). Conclusão: Isquemia miocárdica investigada com ecocardiografia sob estresse físico foi senelhante nos grupos estudados.

Square-wave voltammetric determination of propranolol and atenolol in pharmaceuticals using a boron-doped diamond electrode.

The independent determination of two beta-blocker agents, namely propranolol (PROP) and atenolol (ATN), in pharmaceutical formulations using square-wave voltammetry and a cathodically pretreated boron-doped diamond electrode is described. These electroanalytical determinations of propranolol or atenolol were carried out in 0.1molL(-1) H(2)SO(4) or 0.5molL(-1) NaNO(3) (pH 1.0, adjusted with concentrated HNO(3)), respectively. Excellent linear calibration curves, ranging from 0.20 to 9.0micromolL(-1) for PROP and from 2.0 to 41micromolL(-1) for ATN, with detection limits of 0.18 and 0.93micromolL(-1), respectively, were obtained. The obtained recoveries range from 93.9% to 105.0%, for PROP, and from 92.5% to 106.0%, for ATN. The proposed method was successfully applied in the determination of both beta-blockers in several pharmaceutical formulations (tablets), with results in close agreement at a 95% confidence level with those obtained using official spectrophotometric methods.

Development of a fast capillary electrophoresis method for the determination of propranolol-Total analysis time reduction strategies.

The aim of this study was to develop a fast capillary electrophoresis method for the determination of propranolol in pharmaceutical preparations. In the method development the pH and constituents of the background electrolyte were selected using the effective mobility versus pH curves. Benzylamine was used as the internal standard. The background electrolyte was composed of 60mmolL(-1) tris(hydroxymethyl)aminomethane and 30mmolL(-1) 2-hydroxyisobutyric acid, at pH 8.1. Separation was conducted in a fused-silica capillary (32cm total length and 8.5cm effective length, 50microm I.D.) with a short-end injection configuration and direct UV detection at 214nm. The run time was only 14s. Three different strategies were studied in order to develop a fast CE method with low total analysis time for propranolol analysis: low flush time (Lflush) 35runs/h, without flush (Wflush) 52runs/h, and Invert (switched polarity) 45runs/h. Since the three strategies developed are statistically equivalent, Wflush was selected due to the higher analytical frequency in comparison with the other methods. A few figures of merit of the proposed method include: good linearity (R(2)>0.9999); limit of detection of 0.5mgL(-1); inter-day precision better than 1.03% (n=9) and recovery in the range of 95.1-104.5%.

Hydrophobicity-aided potentiometric detection of catecholamines, beta-agonists, and beta-blockers in a mixed-solvent capillary electrophoresis system.

A series of cationic drug-like substances with distinct basicity, hydrogen-bonding ability, and hydrophobicity, including three catecholamines, two beta-agonists, and thirteen beta-blockers, was successfully detected in a capillary electrophoresis system using an end-capillary coupled potentiometric sensor consisting of a PVC-based liquid membrane deposited directly on a 100 mum diameter copper rod. The electrophoretic separation was performed on a 72 cm x 75 microm id uncoated fused-silica capillary with an acidic background electrolyte containing phosphoric acid in a water-acetonitrile mixture, pH* 2.8. Samples were injected electrokinetically at 5.0 kV for 10 s and a running voltage of 19.5 kV was applied. Excluding the bufuralol/practolol pair, baseline separation of all substances was achieved in the developed CE system within 9 minutes. A linear relationship (R(2) 0.8752) between the sensitivity of the applied potentiometric detector and the parameter log P characterising the hydrophobicity of the analytes was demonstrated. The best observable limits of detection (LODs) were obtained for the highly hydrophobic substances, i. e. bufuralol (8.10 x 10(-8) M injected concentration, S/N = 3), propranolol, alprenolol, and clenbuterol (ca. 1.10 x 10(-7) M). In the case of hydrophilic catecholamines and carbuterol their LODs with potentiometric detection were lowered by a factor of almost one thousand, reaching a value of 6.6 x 10(-5) M.

Quantitative analysis of beta-blockers in pharmaceutical preparations by capillary electrophoresis.

A simple capillary electrophoresis method was developed for the analysis of four beta-blockers (atenolol, metoprolol, pindolol, and propranolol) in pharmaceutical preparations. The method was validated regarding accuracy, precision, linearity, and detection/quantification limits, and the obtained values were in accordance to those reported in the literature. The method was applied to the determination of the drugs in commercial tablet preparations and proved to be fast and reliable for the quantitative analysis of the beta-blockers.

Mass spectrometric study of the photooxidation of the ophthalmic drugs timolol and pindolol.

A mass spectrometric study of the photooxidation products of the ophthalmic drugs pindolol (1-[1H-indol-4-yloxyl]-3-[isopropylamino]-2-propanol) and timolol (S-[-]-1-[t-butylamino]-3-[(4-morpholino-1,2,5-thiadiazol-3-yl)oxyl]-2-propanol) in water has been performed by LC-MS. Based on these data and the assumption that photooxidation mainly occurs through singlet molecular oxygen attack, a possible reaction mechanism is proposed. The mechanistic pathways involve singlet oxygen attack to the pindolol indole ring and oxidation of the pindolol isopropyl or timolol terbutyl methyl groups.

Enantioselective analysis of atenolol in biologic fluids: comparison of liquid-liquid and solid-phase extraction methods.

In this study we evaluated a liquid-liquid extraction procedure and a solid-phase extraction procedure for sample preparation for the enantioselective analysis of atenolol in plasma and urine by high-performance liquid chromatography. A Chiralcel OD-H column was used for the resolution of atenolol enantiomers with hexane-ethanol (85:15, v/v) plus 0.1% diethylamine as the mobile phase. In the liquid-liquid extraction procedure, atenolol was extracted from alkalinized body fluids with 5 ml chloroform-2-propanol (4:1, v/v). In the solid-phase extraction procedure, atenolol was isolated from plasma using a C8 column and methanol. Both extraction procedures were efficient in recovering atenolol and removing endogenous interferents. The RSDs and deviation from nominal values were lower than 10% for both within-day and between-day assays. The results show that there were no statistically significant differences in between-day variation. The t-test showed that there were no significant differences between the real concentrations and the determined concentrations. The limit of quantitation was 10 ng/ml and the linear range was 10-5,000 ng/ml for both methods. These methods can be used in pharmacokinetic studies.

Separação enantiomérica de fármacos em medicamentos por cromatografia líquida com fase estacionária quiral / Enantiomeric separation of drugs in medicine by liquid chromatography with chiral stationary phase

A maioria dos agentes terapêuticos, freqüentemente prescritos, são formulados e comercializados sob a forma racêmica, embora para alguns deles, já tenha sido demonstrado que os efeitos farmacológicos e/ou tóxicos estejam relacionados apenas a um dos enantiômeros. Além disso, é conhecido o fato de que os enantiômeros podem apresentar perfis farmacocinéticos e farmacodinâmicos diferentes. Neste trabalho foram selecionados fármacos que fazem parte de dois grupos importantes no uso clínico. São fármacos freqüentemente prescritos, como os BETA-bloqueadores (atenolol, metoprolol, pindolol, betaxolol e nadolol) e os antiinflamatórios não-esteróides (ibuprofeno e flurbiprofeno)...

Enantiomeric separation and quantitative determination of propranolol in tablets by chiral high-performance liquid chromatography.

This work reports an application of chiral high-performance liquid chromatography (HPLC) in the separation and quantitative determination of propranolol isomers in tablets. The isomers were separated using a Chiralcel OD column (250 x 4.6 mm, 10 microm) with a mobile phase of hexane:ethanol (75:25 v/v) at a flow rate of 0.7 ml/min and ultraviolet detection at 280nm. The coefficient of variation and average recovery of (R)-isomer for samples A, B, C, and D were 0.72% and 100.30%, 0.67% and 99.40%, 0.62% and 99.76%, and 0.70% and 99.68%, respectively. The coefficient of variation and average recovery of (S)-isomer for samples A, B, C, and D were 0.74% and 99.62%, 0.64% and 100.27%, 0.71% and 99.99%, and 0.70% and 99.72%, respectively.

Development and validation of a chiral liquid chromatographic method for the determination of atenolol and metoprolol enantiomers in tablet preparations.

Atenolol (AT) and metoprolol (MT) are predominantly used in the treatment of angina pectoris, certain arrhythmias, systemic hypertension, and several other cardiovascular disorders. Both compounds are produced commercially in the racemic form, although the S-form is responsible for the desired biological effect. This paper describes a simple, rapid, precise, and accurate method for separating the enantiomers of AT and MT. AT isomers are separated by using a Chiralcel OD column (250 x 4.6 mm, 10 microm), hexane-ethanoldiethylamine-acetic acid (60 + 40 + 0.2 + 0.2, v/v/v/v) as the mobile phase, and a flow rate of 1.0 mL/min. MT isomers are separated by using a mobile phase with the same components in the following proportions (40 + 60 + 0.2 + 0.2, v/v/v/v) and a flow rate of 0.8 mL/min. Ultraviolet detection was at 276 nm for both analytes. The coefficients of variation (CVs) and average recoveries (ARs) for the R-enantiomers in samples A, B, C, D, and E were 1.15 and 101.06%, 0.74 and 99.25%, 1.05 and 102.57%, 0.84 and 101.57%, and 0.86 and 98.62%, respectively. The CVs and ARs for the S-enantiomers in samples A, B, C, D, and E were 1.33 and 98.87%, 0.99 and 100.76%, 1.17 and 101.69%, 1.26 and 100.39%, and 1.40 and 99.39%, respectively. The standard curves of R-AT, S-AT, R-MT, and S-MT showed good linearity over the concentration range studied with correlation coefficients of 0.9991, 0.998, 0.9988, and 0.999, respectively.

Efectos del esmolol sobre las respuestas hemodinámicas derivadas de la inducción de la anestesia y la intubación / The effects of esmolol on the hemodinamic response after anesthesia induction and endotracheal intubation

El clorhidrato de esmolol es el prototipo de una nueva generación de agentes bloqueadores de los receptores adrenérgicos beta1 cuya característca principal es su acción ultra-corta (t1/2 de acción 9 minutos). Se investigaron los efectos del esmolol administrado por vía intravenosa sobre la frecuencia de hipertensión arterial y taquicardia derivadas de la inducción de la anestesia y la intubación traqueal en un grupo de 22 pacientes adultos de ambos sexos con RAQI a II (ASA). Los resultados obtenidos se compararon con los de un grupo control de 20 pacientes con las mismas características pero que no recibieron esmolol. Prácticamente en todos los tiempos antes y después de la intubación traqueal se encontraron diferencias estadísticamente significativas en las cifras de las presiones arteriales sistólica, media, diastólica y frecuencia cardiaca entre ambos grupos (P<0.02 a P<0.001). Consideramos al esmolol efectivo para atenuar la hipertensión y taquicardia derivadas de la inducción de la anestesia e intubación de la traquea.

Eficácia e segurança do carteolol a 2 por cento no tratamento da hipertensäo ocular crônica / Efficacy and safety of the 2 percent carteolol solution for the treatment of chronic ocular hypertension

Foram avaliadas a eficácia como agente hipotensor ocular e a segurança do colírio de maleato de timolol a 0,5//, em 34 indivíduos portadores de hipertensäo ocular ou glaucoma primário de ângulo aberto, por 12 semanas. Os resultados obtidos mostraram equivalência das duas drogas como agentes hipotensores oculares, nos diferentes momentos de estudo. A soluçäo de hidrocloreto de carteolol a 2//, assim como a de maleato de timolol a 0,5//, näo mostrou efeitos colaterais locais ou cardiovasculares

Structure-basicity and structure-affinity relationships of beta-adrenergic blocking agents.

pKa's of fourteen beta-receptor blockers, isoproterenol and norepinephrine, were determined potentiometrically. A Hammett analysis indicated that the influence of ring substituents on the basicity of the amines is attenuated by the ethanolic chain and abolished by the propranoloxy chain of beta-receptor blockers. The effect of ring substituents in phenoxypropranolamines upon affinity for the beta-adrengeric receptors is therefore unrelated to the strength of the bases. Two alterantive hypotheses are fowarded to explain why phenoxypropranolamines have greater affinities for the beta-receptors than phenethanolamines.