Beneficial effects of nebivolol treatment on oxidative stress parameters in patients with slow coronary flow

OBJECTIVES

Imbalance between oxidative stress and antioxidant defense has been demonstrated in patients with slow coronary flow (SCF). The aim of this study was to investigate the effect of nebivolol treatment on oxidative stress parameters in SCF patients.

STUDY DESIGN

The study included 32 patients (10 females, 22 males; mean age 53.3 ± 5.2 years) with SCF and 32 control subjects (14 females, 18 males; mean age 50.6 ± 5.2 years) with normal coronary arteries on angiography. Coronary slow flow was determined by the TIMI frame count method. Patients with SCF received nebivolol treatment (5 mg/day) for six months. Blood samples were analyzed for malondialdehyde (MDA) and serum nitric oxide (NO) levels, and erythrocyte catalase (CAT) and erythrocyte superoxide dismutase (SOD) activities in the control group and, in SCF patients, at baseline and after six months of nebivolol treatment.

RESULTS

The two groups were similar with respect to age, body mass index, blood pressure, heart rate, and lipid profile. Smoking was more frequent in the SCF group compared to the controls. TIMI frame counts measured from the left anterior descending, circumflex, and right coronary arteries were significantly higher in the SCF group (p < 0.0001). Baseline MDA and NO levels, and SOD and CAT activities were significantly different between the two groups, with significantly increased MDA (p < 0.0001), and significantly decreased SOD (p < 0.0001), CAT (p < 0.001), and NO (p < 0.001) in the SCF group. After six months of nebivolol treatment, all oxidative stress parameters showed significant improvements compared to the baseline values (p < 0.0001 for MDA, SOD, CAT, and NO) and approximated to the values of the control group.

CONCLUSION

Our results show that nebivolol treatment may be beneficial to improve oxidative stress parameters in patients with SCF, which are considered to be an early stage of atherosclerosis.

Nebivolol/hydrochlorothiazide (HCTZ) combination in patients with essential hypertension: a pooled analysis from five non-interventional studies with a focus on diabetic and elderly patients

BACKGROUND AND OBJECTIVES

Nebivolol is a third-generation beta-blocker, characterized by unique pharmacological properties. The combination of nebivolol and hydrochlorothiazide (HCTZ) has been evaluated in large-scale clinical trials. This post-marketing surveillance analysis evaluated the effectiveness of the nebivolol/HCTZ combination in a "real-life" setting that included diabetic and elderly patients.

PATIENTS AND METHODS

The analysis was based on data from five non-interventional studies conducted in Germany, which lasted up to 12 weeks. Data from patients treated with nebivolol/HCTZ 5/12.5 mg/day in combination were pooled. The following parameters were calculated at the final visit, in the whole population and in elderly (>70 years) and diabetic subgroups: (1) difference from baseline in diastolic blood pressure (DBP) and in systolic blood pressure (SBP); (2) percentage of responder patients (reduction in DBP or SBP of 10 or 20 mmHg, respectively). Alterations in laboratory parameters were also monitored.

RESULTS

In total, 86 patients (mean age 58.9 +/- 10.8 years) were included in the analysis. Nebivolol/HCTZ significantly reduced both DBP (-11.8 +/- 7.9 mmHg; p<0.0001 vs baseline) and SBP (-22.5 +/- 13.5 mmHg; p<0.0001 vs baseline). In total, 81.4% of patients were responders (75% and 83.3% in elderly and diabetic patients, respectively). No clinically significant alterations in laboratory parameters were observed.

DISCUSSION

This study confirms that nebivolol/HCTZ is an effective and well tolerated therapeutic strategy in a real-life setting as well as in clinical trials. Therefore, this combination may represent a first-choice therapy in the management of hypertension.

Nebivolol prevents remodeling in a rat myocardial infarction model: an echocardiographic study

OBJECTIVE

Ventricular remodeling (VR) which develops after myocardial infarction (MI) plays an important role in progressive left ventricular dysfunction. We aimed to investigate the role of nebivolol treatment on VR after a MI in a rat ischemia-reperfusion model.

METHODS

Rats were divided into 3 groups of 12 each: sham operated (sham-control), MI-induced (MI-control) and nebivolol treated (MI-nebivolol). Left ventricular (LV) diameters, volumes, and diastolic filling parameters were evaluated by echocardiography. On the 28th day, after recording the systemic and LV pressures and determining the plasma nitric oxide (NO) and peroxynitrite (ONOO-) levels , animals were sacrificed and heart, body and LV weights (HW, BW, LVW) were measured and infarct sizes were determined. Results were evaluated statistically by ANOVA for repeated measurements 3x3 factorial design with post-hoc Bonferroni test.

RESULTS

After MI, while VR (an increase in LV diameters and volumes associated with a decrease in EF, FS and posterior wall thickness change (LWPc) was significant in MI-control rats (p<0.05 for; all comparisons) these changes were significantly less in MI-nebivolol group (p=0.08 and p=0.06 for EF and FS respectively). LV end diastolic pressure (LVEDP) was lower (p<0.005) and Delta+/- dp/dt's (p<0.05) were higher in MI-nebivolol group compared to MI-control animals. Although infarct sizes were similar in MI-induced groups (p=0.79); LVW/HW and HW/BW's were significantly greater in the MI-control group compared to sham-control (p<0.01 for all comparisons), these changes were not statistically significant in MI-nebivolol group. The increase in plasma NO and ONOO- levels were also prevented with nebivolol.

CONCLUSION

Nebivolol therapy reduced the effects of VR in rats after MI. These beneficial effects were not related to its heart rate and blood pressure reducing effects. Nitric oxide regulatory action of this compound may contribute these beneficial effects on VR developed after MI.

Nebivolol attenuates maladaptive proximal tubule remodeling in transgenic rats

BACKGROUND/AIMS

The impact of nebivolol therapy on the renal proximal tubular cell (PTC) structure and function was investigated in a transgenic (TG) rodent model of hypertension and the cardiometabolic syndrome. The TG Ren2 rat develops nephropathy with proteinuria, increased renal angiotensin II levels and oxidative stress, and PTC remodeling. Nebivolol, a beta(1)-antagonist, has recently been shown to reduce albuminuria, in part, through reductions in renal oxidative stress. Accordingly, we hypothesized that nebivolol therapy would attenuate PTC damage and tubulointerstitial fibrosis.

METHODS

Young Ren2 (R2-N) and SD (SD-N) rats were treated with nebivolol (10 mg/kg/day) or vehicle (R2-C; SD-C) for 3 weeks. PTC structure and function were tested using transmission electron microscopy and functional measurements.

RESULTS

Nebivolol treatment decreased urinary N-acetyl-beta-D-glucosaminidase, tubulointerstitial ultrastructural remodeling and fibrosis, NADPH oxidase activity, 3-nitrotyrosine levels, and increased megalin and lysosomal-associated membrane protein-2 immunostaining in PTCs. Ultrastructural abnormalities that were improved with therapy included altered canalicular structure, reduced endosomes/lysosomes and PTC vacuoles, basement membrane thickening, and mitochondrial remodeling/fragmentation.

CONCLUSION

These observations support the notion that nebivolol may improve PTC reabsorption of albumin and other glomerular filtered small molecular weight proteins in association with the attenuation of oxidative stress, tubulointerstitial injury and fibrosis in this rat model of metabolic kidney disease.

The effect of nebivolol on atherogenesis in apoE-knockout mice

Nebivolol is a novel beta1-blocker with a nitric oxide (NO)--potentiating, vasodilatory effect that is unique among beta-blockers. It was already shown that nebivolol ameliorates atherosclerosis in cholesterol-fed rabbits. We, therefore, wanted to investigate whether this is the case in the fine experimental model of atherosclerosis: apolipoprotein E (apoE)-knockout mice. Nebivolol attenuated atherogenesis, measured both by "en face" method (9.23+/-1.8% vs. 14.6+/-2.1%) and "cross-section" method (63125+/-8455 microm(2) vs. 91416+/-8357 m(2)). This is the first report showing the effect of nebivolol on atherogenesis in gene-targeted mice.

Quality of life and efficacy of nebivolol in an open-label study in hypertensive patients. the QoLaN study

BACKGROUND

Nebivolol is a highly selective beta-adrenoreceptor antagonist with vasodilating properties. This study investigated its effect on quality of life (QoL) and blood pressure (BP) in real life conditions. In total, 1468 patients were enrolled, 12% diabetics. Nebivolol was prescribed as monotherapy, add-on or switch medication.

METHODS

In this open-label, prospective study, the JNC-VII BP target values were used: < 140/90 and < 130/80 mmHg for diabetics. The responder rate and the QoL was determined at baseline and after 4 and 8 weeks.

RESULTS

After 4 weeks, 27% of subjects reached target BP, 45% after 8 weeks. The responder rates were 92, 90 and 83% for the monotherapy, add-on and switch groups. Compared with baseline, all showed statistical significance at 8 weeks. Similarly to results for the QoL after 8 weeks, the mean improvement in QoL for all three groups was 9-10 points (total range: 0-88).

CONCLUSIONS

The study demonstrates that nebivolol in mild to moderate hypertension is associated with overall improvements in QoL, with a marked BP-lowering effect, in monotherapy, add-on or switch, irrespective of the glucose tolerance status. It may be hypothesized that its dual mode of action explains its BP-lowering effect as well as the tolerability.

Nebivolol therapy improves endothelial function and increases exercise tolerance in patients with cardiac syndrome X

OBJECTIVE

We sought to determine whether nebivolol affects coronary endothelial function and exercise induced ischemia in patients with cardiac syndrome X (CSX).

METHODS

The study protocol undertaken was based on a single-blind randomized controlled prospective study. After a 2-week washout period, 38 patients with cardiac syndrome X were randomized to receive either nebivolol 5 mg daily (n=19) or metoprolol 50 mg daily (n=19) in a single- blind design for 12 weeks. The control group under study was consisted of 16 age- and gender-matched subjects with negative treadmill exercise tests. Plasma endothelial nitric oxide (NOx), L-arginine, and asymmetric dimethylarginine (ADMA) were measured in all patients at baseline and after 12 weeks of treatment. Statistical differences among groups were tested by one-way analysis of variance and unpaired samples t test for parametric; Kruskal-Wallis and Mann-Whitney U tests for non-parametric variables, respectively. A paired samples t test was used to compare continuous variables before and after drug therapy.

RESULTS

At baseline, plasma level of NOx, L-arginine, and L-arginine/ADMA ratio were lower (p<0.001 for all) in patients with CSX than in the control patients. Whereas, the plasma ADMA levels were increased in the patient group (p<0.001). After 12 weeks of drug therapy, the patients taking nebivolol had increased levels of plasma NOx , plasma L-arginine, the L-arginine/ADMA ratio and decreased levels of plasma ADMA compared to those of the patients taking metoprolol (p<0.001). In addition, exercise duration to 1-mm ST depression and total exercise duration significantly increased after treatment in the nebivolol group compared to the metoprolol group (p<0.01). In the nebivolol group, Canadian Cardiovascular Society (CCS) angina classification improved by one or more categories in 12 (70%) patients, whereas it deteriorated or remained in the same category in 5 (30%) patients. Meanwhile, in the metoprolol group, the CCS angina classification improved by one or more categories in 7 (41%), whereas it deteriorated or remained in the same category in 10 (59%) patients.

CONCLUSION

Circulating endothelial function parameters (plasma ADMA, L-arginine, NOx levels) were impaired in patients with CSX. Nebivolol treatment was associated with better improvements in both circulating endothelial function and exercise stress test parameters than metoprolol. We believe that further studies are needed to evaluate the effects of nebivolol treatment on long-term clinical outcomes in patients with CSX.

Validation and application of high-performance liquid chromatographic and spectrophotometric methods for simultaneous estimation of nebivolol and hydrochlorothiazide: a novel approach to multivariate calibrations by R-Software Environment

A fast, simple reversed-phase HPLC method and two spectrophotometric methods based on principal component regression and partial least squares calibrations were developed for determination of nebivolol (NEB) and hydrochlorothiazide (HCTZ) in formulations without prior separation or masking. The HPLC assay utilized a Phenomenex-Luna RP-18(2) 250 x 4.6 mm, 5 microm column with acetonitrile--0.03% aqueous formic acid, pH 3.3 (65 + 35, v/v), mobile phase at a flow rate of 1.0 mL/min, and UV detection at 277 nm. The retention times of NEB and HCTZ were 2.133 and 2.877 min, respectively. The total run time was < 4 min. Chemometric calibrations were constructed by using an absorption data matrix corresponding to a concentration data matrix, with measurements in the range of 231-310 nm (Delta lambda = 1 nm) in their zero-order spectra using 16 samples in a training set. The chemometric numerical computations were obtained by using R-Software Environment (Version 2.1.1). The proposed methods were validated for various International Conference on Harmonization regulatory parameters like linearity, range, accuracy, precision, robustness, LOD, LOQ, and HPLC system suitability. Laboratory-prepared mixtures and commercial tablet formulations were successfully analyzed using the developed methods. All results were acceptable and confirmed that the method is suitable for its intended use.

The effects of nebivolol on P wave duration and dispersion in patients with coronary slow flow

OBJECTIVE

Coronary slow flow (CSF) is characterized by delayed opacification of coronary arteries in the absence epicardial occlusive disease. P wave duration and dispersion have been reported to be longer in patients with CSF. Nebivolol, besides its selective beta1-blocking activity, causes an endothelium dependent vasodilatation through nitric oxide release. In this study, we searched for the association between left ventricular diastolic functions and atrial conduction dispersion, the effects of nebivolol on P wave duration and dispersion in patients with CSF.

METHODS

This prospective case-controlled study included 30 patients having CSF and 30 subjects having normal coronary arteries in coronary angiography. The patients were evaluated with 12-leads electrocardiography and echocardiography before and three months after treatment with nebivolol. The difference between maximum and minimum P wave durations was defined as P-wave dispersion (PWD). Early diastolic flow (E), atrial contraction wave (A) and E deceleration time (DT) and isovolumetric relaxation time (IVRT) were measured. Unpaired and paired t-tests, Chi-square test, Mann-Whitney's U-test and Pearson correlation analysis were used in statistical analysis.

RESULTS

Compared to control group maximum P wave duration (Pmax) (104.3+/-12.2 vs. 93.4+/-9.8 msec, p<0.001) and PWD (35.0+/-8.6 vs. 24.8+/-5.4 msec, p<0.001), DT (245.4+/-54.9 vs. 198.0+/-41.7 msec, p<0.001) and IVRT (112.9+/-20.8 vs. 89.5+/-18.2 msec, p<0.001) were significantly longer and E/A ratio (0.89+/-0.27 vs. 1.27+/-0.27, p<0.001) was lower in patients with CSF as compared with control subjects. There were no significant correlations of Pmax and PWD with clinical and echocardiographic variables. Systolic and diastolic blood pressures (130.5+/-15.5 mmHg to 117.8+/-12.3 mmHg and 84.5+/-9.8 mmHg to 75.0+/-6.2 mmHg, p<0.001), Pmax (to 98.7+/-11.7 msec, p=0.038), PWD (to 21.3+/-5.1 msec, p<0.001) and DT (to 217.3+/-41.4 msec, p<0.001) and IVRT (to 101.2+/-17.4 msec, p<0.001) significantly decreased and E/A ratio (to 1.1+/-0.23, p<0.001) significantly increased after treatment with nebivolol. Correlation analysis revealed that the change in PWD was not significantly correlated with any of the clinical and echocardiographic variables including decrease in blood pressures.

CONCLUSION

Coronary slow flow is associated with prolonged P wave duration and dispersion and impaired diastolic filling. Nebivolol may be helpful in restoration of these findings. P wave duration and dispersion may not be associated with left ventricular function parameters in patients with CSF.

Nebivolol reduces proteinuria and renal NADPH oxidase-generated reactive oxygen species in the transgenic Ren2 rat

BACKGROUND/AIMS

Renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system activation are crucial in the pathogenesis of hypertension, cardiovascular and renal disease. NADPH oxidase-mediated increases in reactive oxygen species (ROS) are an important mediator for RAAS-induced cardiovascular and renal injury. Increased levels of ROS can diminish the bioactivity of nitric oxide (NO), a critical modulator of RAAS effects on the kidney. Thereby, we hypothesized that in vivo nebivolol therapy in a rodent model of activated RAAS would attenuate glomerular damage and proteinuria through its actions to reduce NADPH oxidase activity/ROS and increase bioavailable NO.

METHODS

We utilized the transgenic Ren2 rat which displays heightened tissue RAAS, hypertension, and proteinuria. Ren2 rats (6-9 weeks of age) and age-matched Sprague-Dawley littermates were treated with nebivolol 10 mg/kg/day (osmotic mini-pump) for 21 days.

RESULTS

Ren2 rats exhibited increases in systolic blood pressure, proteinuria, kidney cortical tissue total NADPH oxidase activity and subunits (Rac1, p67(phox), and p47(phox)), ROS and 3-nitrotyrosine, as well as reductions in podocyte protein markers; each of these parameters improved with nebivolol treatment along with increases in renal endothelial NO synthase expression.

CONCLUSIONS

Our data suggest that nebivolol improves proteinuria through reductions in renal RAAS-mediated increases in NADPH oxidase/ROS and increases in bioavailable NO.

Clinical pharmacodynamics of nebivolol: new evidence of nitric oxide‐mediated vasodilating activity and peculiar haemodynamic properties in hypertensive patients

New evidence from recently completed clinical studies performed with nebivolol, a highly selective beta-1 beta-blocker, endowed with additional vasodilating activity mediated by nitric oxide (NO) endothelial release, confirm previous findings that nebivolol differs from other beta-blocking agents and that the combination of beta-1 blockade and NO-mediated vasodilation not only potentiates the blood pressure lowering activity, but leads to a broader favourable haemodynamic profile, which is clinically relevant to the treatment of hypertensive patients. In particular, six new studies focusing on the vasodilation properties of nebivolol demonstrated that: (i) its blood pressure lowering effect is accompanied by a vasodilating action that is seen after single and chronic administration of the usual antihypertensive oral dose of 5 mg once daily; (ii) the vasodilation can be documented systemically, at various regional vascular beds and skin microcirculation, and is accompanied by increased small arterial distensibility; (iii) the NO-endothelium-dependency of its vasodilating action is shown by the model of forearm or cutaneous vasodilating response to acetylcholine and by the blockade of the nebivolol-induced local vasodilation by a blocker of the arginine-NO cascade, L-NMMA. Two more studies demonstrated the ability of nebivolol to increase NO concentrations through preservation of NO from oxidative degradation, and not only by stimulation of its synthesis. Finally, two studies confirmed the favourable haemodynamic action of nebivolol on both systolic and diastolic function and, in particular, an increase in stroke volume, associated with reduction in vascular resistance, resulting in a maintained cardiac output despite reduced heart rate. These properties consistently differentiate nebivolol from non-vasodilating beta-blockers, such as those used for the active comparative studies, i.e. atenolol, metoprolol or bisoprolol. The observation that nebivolol enhances or restores NO-mediated vasodilation in hypertensive patients has important therapeutic implications in view of the well-established protective role of NO against cardiovascular risk factors, and particularly the development of atherosclerosis. Similarly, the favourable haemodynamic profile of nebivolol, as described by the new investigations (preservation of cardiac output, reduction of peripheral resistance and improved diastolic function) appear to have clinically relevant benefits on the impairment in systolic and/or diastolic function often complicating the hypertension.

Radical scavenging and NO-releasing properties of selected β-adrenoreceptor antagonists

It is claimed that novel beta-adrenolytic drugs possess superior antioxidant properties as compared to classical selective or non-selective beta-adrenoceptor antagonists. Here we tested this notion by analyzing radical scavenging properties of selected beta-adrenolytic drugs and their ability to release nitric oxide in biological preparations. Selective beta1-adrenolytics such as nebivolol, atenolol, metoprolol and non-selective beta-adrenolytics with alpha1-receptor blocking properties such as carvedilol and labetalol were chosen for analysis. NO-releasing properties of nebivolol and carvedilol distinguished third generation beta-adrenolytics from their older counterparts while the reactivity towards hydroxyl and peroxyl radicals discerns only carvedilol but not nebivolol. Thus, superior clinical efficacy of third generation beta-adrenolytics may be related to their ability to release NO rather then to their direct antioxidant properties.

Gender Dependency of Circadian Blood Pressure and Heart Rate Profiles in Spontaneously Hypertensive Rats: Effects of Beta‐Blockers

This study investigated (i) blood pressure (BP), heart rate (HR), and their relation to urinary NOx and eNOS protein expression in male and female spontaneously hypertensive rats (SHR), as well as (ii) gender-dependent cardiovascular effects of nebivolol (NEB) in comparison to metoprolol (MET) in SHR. BP and HR were measured telemetrically after a single intraperitoneal application of NEB or MET at 07.00 and 19.00 h in male rats and at 19.00 h in proestrus female rats. The two beta-blockers varied in time of decreasing BP and HR and also in duration. In males, MET decreased BP and HR for few hours exclusively when applied at the onset of the activity phase (i.e., at 19.00 h), while after its application at 07.00 h, BP and HR were unchanged. In females, MET also caused a short-lasting BP and HR reduction, with the effect being more pronounced than in males. In males, NEB at either dosing time decreased HR and BP to a greater extent than did MET. This effect was evident both during the activity and rest periods and persisted for at least five days. In females, NEB provoked a similar, but more pronounced, effect on BP and HR in comparison to males. These findings demonstrate that significant gender-dependent differences in the circadian profile of BP and HR exist. BP and urinary NOx as well as eNOS expression are inversely correlated, and the cardiovascular effects of NEB and MET vary, depending on the time of application as well as gender.

New drug update: 2008

Only 16 new therapeutic agents were marketed in the United States in 2008, the lowest number in many years. Four new drugs have been selected for consideration in this review. The uses and most important properties of each agent are considered, and a rating for each new drug is provided using the New Drug Comparison Rating (NDCR) system developed by the author.

[Correction of portal hypertension and renal dysfunction with help of nebivolol and lizinopril in patients with hepatic cirrhosis]

The effect of nebevolol, beta-blocker on the portal hypertension and renal blood flow and the safety of its use versus lisinopril, an angiotensin-converting enzyme inhibitor were examined in the patients with cirrhosis. 72 patients were examined (39 patients with cirrhosis of the liver without ascites - the 1st group and 32 patients with cirrhosis of the liver with ascites - the 2nd group. Trustworthy decrease of portal hypertension parameters (the decrease of portovenosis gradient of pressure (PPG) by 19,3% (p = 0,048) in the patients with liver cirrhosis of class A on Child-Pugh without ascites with nebevolol was revealed. The trust worthy changes of portal blood flow was not revealed in all examined patients with lisinopril. But these patients without ascites have demonstrated the improvement of the renal hemodynamic (renal functional reserve (RFR) by 56%, effective renal plasma flow (ERPF) by 17,3%). The lisinopril intake 5 mg a day declines PPG by 18,1%. The tendency of the reduction of the functional index due to the expressed hypotensive effect of nebevolol and lisinopril was revealed in all examined patients with liver cirrhosis. So it was demonstrated that for the management of the portal hypertension in the patients with liver cirrhosis is necessary to examine of functional renal condition to prevent the development of hepatorenal syndrome.

Reduced intimal hyperplasia in rabbits via medical therapy after carotid venous bypass

Intimal hyperplasia is a major cause of restenosis after the interventional or surgical treatment of occlusive arterial disease. We investigated the effects of clopidogrel, calcium dobesilate, nebivolol, and atorvastatin on the development of intimal hyperplasia in rabbits after carotid venous bypass surgery. We divided 40 male New Zealand rabbits into 4 study groups and 1 control group. After occluding the carotid arteries of the rabbits, we constructed jugular venous grafts between the proximal and the distal segments of the occluded artery. Thereafter, group 1 (control) received no medication. We administered daily oral doses of clopidogrel to group 2, calcium dobesilate to group 3, nebivolol to group 4, and atorvastatin to group 5. The rabbits were killed 28 days postoperatively. The arterialized jugular venous grafts were extracted for histopathologic examination. Intimal thicknesses were 42.87 +/- 6.95 microm (group 2), 46.5 +/- 9.02 microm (group 3), 34.12 +/- 5.64 microm (group 4), and 48.37 +/- 6.16 microm (group 5), all significantly less than the 95.12 +/- 9.93 microm in group 1 (all P < 0.001). Medial thicknesses were 94 +/- 6 microm (group 2), 101.5 +/- 13.52 microm (group 3), 90.5 +/- 9.69 microm (group 4), and 101.37 +/- 7.99 microm (group 5), all significantly thinner than the 126.62 +/- 13.53 microm in group 1 (all P < 0.001). In our experimental model of carotid venous bypass grafting in rabbits, clopidogrel, calcium dobesilate, nebivolol, and atorvastatin each effectively reduced the development of intimal hyperplasia. Herein, we discuss our findings and review the medical literature.

[Optimization of use of beta-adrenoblockers in the treatment of chronic heart failure in the outpatient setting]

AIM

to evaluate of the effectiveness of switching from beta-adrenoblockers (BAB) non-included into the guidelines for the management of chronic heart failure (CHF) to nebivolol and bisoprolol for outpatients.

SUBJECTS AND METHODS

The study included 67 patients with stable Functional Classes (FC) II and II CHF who received the standard therapy and BAB non-included into the guidelines for the management of CHF. The patients were randomized to the groups taking bisoprolol (n = 35) or nebivolol (n = 32) in doses of 1.25 to 10 mg/day. Before and 6 months after therapy, the investigators assessed the patient's clinical status and quality of life (QL), performed a six-minute walk test and echography, and determined the blood level of the N-terminal fragment of brain natriuretic peptide prohormone (NT-proBNP).

RESULTS

The switching to bisoprolol and nebivolol was followed by a significant clinical improvement, a larger covered distance, and better QL. Left ventricular ejection fraction was increased along with a reduction in mean FC CHF. There were no significant changes in NT-proBNP in the total patient group, but it was significantly decreased in the subgroup of those with the baseline high level of the peptide.

CONCLUSION

The switching of patients with stable CHF from therapy with BAB not included into the guidelines for the management of CHF to nebivolol or bisoprolol yields positive results and improves left ventricular systolic function (which is attended by the reduction in NT-proBNP levels) and may be recommended for treatment in the outpatient setting.

Determination of nebivolol hydrochloride and hydrochlorothiazide in tablets by first-order derivative spectrophotometry and liquid chromatography

Two simple and accurate methods for analysis of nebivolol hydrochloride (NEB) and hydrochlorothiazide (HCTZ) in their combined dosage forms were developed using first-order derivative spectrophotometry and reversed-phase liquid chromatography (LC). NEB and HCTZ in their combined dosage forms (tablets) were quantified using first-derivative responses at 294.6 and 334.6 nm in the spectra of their solutions in methanol. The calibration curves were linear in the concentration range of 8-40 microg/mL for NEB and 10-60 microg/mL for HCTZ. LC analysis was performed on a Phenomenex Gemini C18 column (250 x 4.6 mm id, 5 microm particle size) in the isocratic mode with 0.05 M potassium dihydrogen phosphate-acetonitrile-methanol (30 + 20 + 50, v/v/v; pH 4) mobile phase at a flow rate of 1 mL/min. Detection was made at 220 nm. Both of the drugs and the internal standard (ezetimibe) were well resolved with retention times of 5.1 min for NEB, 2.9 min for HCTZ, and 8.2 min for ezetimibe. The calibration curves were linear in the concentration range of 1-14 microg/mL for NEB and 0.3-28 microg/mL for HCTZ. Both methods were validated and found to be accurate, precise, and specific, and results were compared statistically. Developed methods were successfully applied for the estimation of NEB and HCTZ in their combined dosage forms.

Protective effects of nebivolol on oxygen free radical-induced vasoconstrictions in vitro

BACKGROUND

Disturbed ocular hemodynamics and vasospasms might be involved in the pathogenesis of glaucoma. On a clinical level there are indications for an optimization of ocular perfusion parameters in hypertensive glaucoma patients by switching a beta-adrenoceptor-antagonist therapy to nebivolol. Aim of the present study is to investigate vasoactive properties of nebivolol on ocular vasculature in vitro. Besides vasorelaxing effects, the impact of nebivolol on oxygen free radical-induced vasoconstrictions is studied.

MATERIAL/METHODS

The experiments were carried out with ring preparations from porcine ciliary arteries. The preparations were placed in a myograph system and were kept under physiological conditions (pH 7.4, 37 degrees C, Krebs-Henseleit-Buffer, 1.75 mM Ca2+) and were stimulated by K+ depolarizations. The experiments were performed at a Nernst potential of -41 mV, which reflects half-maximal activation. For radical exposure, the preparations were superfused for 20 s in a specifically designed set-up with hydroxyl radicals generated by the Fenton reaction from H2O2 and Fe3+. NO synthase activity was modulated by adding L-arginine to the buffer.

RESULTS

At a concentration of 10-5 M nebivolol leads to a reduction of vascular tone by -8.5+/-3.4% (n=11; P=0.016) vs. +2.6+/-1.9% (n=11; n.s.) in presence of its solvent DMSO. Nebivolol (10-5 M) reduces hydroxyl radical-induced vasoconstrictions by 53+/-10% (n=11; P<0.001). Stimulation of the NO synthase by L-arginine saturation potentiates this effect.

CONCLUSIONS

Nebivolol combines vasorelaxing properties with protection against oxidative stress-induced vasoconstrictions. Both effects may be attributed to NO-releasing properties of nebivolol independently of its beta-adrenoceptor-blocking effect.