Beta-adrenergic blockers in systemic hypertension: pharmacokinetic considerations related to the current guidelines

A Retrospective Review of Cardiogenic Shock Development in Patients With ST-Elevation Myocardial Infarction and Percutaneous Coronary Intervention Receiving Early Beta-Blockers

ABSTRACT

Beta-blockers (BBs) have proven to improve morbidity and mortality in patients after an ST elevation myocardial infarction (STEMI). Guidelines suggest initiating a BB within 24 hours, except in those with risk factors for developing cardiogenic shock, although published literature is conflicting regarding the true association of these risk factors with shock. This retrospective cohort study aimed to assess whether the presence of defined risk factors was associated with cardiogenic shock after early BB administration in patients with a STEMI and percutaneous coronary intervention. The primary outcome determined the rate of cardiogenic shock development and secondarily determined any characteristics associated with cardiogenic shock in patients who received beta blockers. The population included 299 patients and cardiogenic shock occurred in 8 patients (2.7%). There were no median (interquartile range) differences in age [63 years (60-71) versus 62 years (52-71); P = 0.4965], systolic blood pressure [110 mm Hg (105-115) versus 109 mm Hg (103-114); P = 0.6027], or heart rate [90 (78-104) versus 76 (64-90); P = 0.0697] before BB administration in patients who developed shock versus those who did not, respectively. Hours to BB administration from arrival [15.6 (6.0-54.8) versus 21.9 (10.6-42; P = 0.6968] and the number (%) with anterior infarction [3 (37.5%) versus 107 (36.8%); P = 1.000] were similar between groups. There was a statistically significant higher median (interquartile range) peak troponin [140 ng/mL (54-304) versus 49 ng/mL (16-132); P = 0.0354] in patients who developed shock. Early initiation of a BB in patients with STEMI and percutaneous coronary intervention with risk factors for cardiogenic shock does not seem to be associated with shock in most patients.

Neuropsychiatric Consequences of Lipophilic Beta-Blockers

Beta-blockers are a class of drugs with important benefits in cardiovascular pathology. In this paper, we aim to highlight their adverse and therapeutic effects in the neuropsychiatric field. With respect to permeability, we would like to mention that most beta-blockers are lipophilic and can cross the blood–brain barrier. Observational studies show the presence of neuropsychiatric side effects when taking beta-blockers, and is the reason for which caution is recommended in their use in patients with depressive syndrome. From a therapeutic point of view, most current evidence is for the use of beta-blockers in migraine attacks, essential tremor, and akathisia. Beta-blockers appear to be effective in the treatment of aggressive behavior, beneficial in the prevention of posttraumatic stress syndrome and may play a role in the adjuvant treatment of obsessive–compulsive disorder, which is refractory to standard therapy. In conclusion, the relationship between beta-blockers and the central nervous system appears as a two-sided coin. Summarizing the neuropsychiatric side effects of beta-blockers, we suggest that clinicians pay special attention to the pharmacological properties of different beta-blockers.

The importance of bone marrow and the immune system in driving increases in blood pressure and sympathetic nerve activity in hypertension

NEW FINDINGS

What is the topic of this review? This manuscript provides a review of the current understanding of the role of the sympathetic nervous system in regulation of bone marrow-derived immune cells and the effect that the infiltrating bone marrow cells may have on perpetuation of the sympathetic over-activation in hypertension. What advances does it highlight? We highlight the recent advances in understanding of the neuroimmune interactions both peripherally and centrally as they relate to blood pressure control.

ABSTRACT

The sympathetic nervous system (SNS) plays a crucial role in maintaining physiological homeostasis, in part by regulating, integrating and orchestrating processes between many physiological systems, including the immune system. Sympathetic nerves innervate all primary and secondary immune organs, and all cells of the immune system express β-adrenoreceptors. In turn, immune cells can produce cytokines, chemokines and neurotransmitters capable of modulating neuronal activity and, ultimately, SNS activity. Thus, the essential role of the SNS in the regulation of innate and adaptive immune functions is mediated, in part, via β-adrenoreceptor-induced activation of bone marrow cells by noradrenaline. Interestingly, both central and systemic inflammation are well-established hallmarks of hypertension and its co-morbidities, including an inflammatory process involving the transmigration and infiltration of immune cells into tissues. We propose that physiological states that prolong β-adrenoreceptor activation in bone marrow can disrupt neuroimmune homeostasis and impair communication between the immune system and SNS, leading to immune dysregulation, which, in turn, is sustained via a central mechanism involving neuroinflammation.

Microengineered systems with iPSC-derived cardiac and hepatic cells to evaluate drug adverse effects

Hepatic and cardiac drug adverse effects are among the leading causes of attrition in drug development programs, in part due to predictive failures of current animal or in vitro models. Hepatocytes and cardiomyocytes differentiated from human induced pluripotent stem cells (iPSCs) hold promise for predicting clinical drug effects, given their human-specific properties and their ability to harbor genetically determined characteristics that underlie inter-individual variations in drug response. Currently, the fetal-like properties and heterogeneity of hepatocytes and cardiomyocytes differentiated from iPSCs make them physiologically different from their counterparts isolated from primary tissues and limit their use for predicting clinical drug effects. To address this hurdle, there have been ongoing advances in differentiation and maturation protocols to improve the quality and use of iPSC-differentiated lineages. Among these are in vitro hepatic and cardiac cellular microsystems that can further enhance the physiology of cultured cells, can be used to better predict drug adverse effects, and investigate drug metabolism, pharmacokinetics, and pharmacodynamics to facilitate successful drug development. In this article, we discuss how cellular microsystems can establish microenvironments for these applications and propose how they could be used for potentially controlling the differentiation of hepatocytes or cardiomyocytes. The physiological relevance of cells is enhanced in cellular microsystems by simulating properties of tissue microenvironments, such as structural dimensionality, media flow, microfluidic control of media composition, and co-cultures with interacting cell types. Recent studies demonstrated that these properties also affect iPSC differentiations and we further elaborate on how they could control differentiation efficiency in microengineered devices. In summary, we describe recent advances in the field of cellular microsystems that can control the differentiation and maturation of hepatocytes and cardiomyocytes for drug evaluation. We also propose how future research with iPSCs within engineered microenvironments could enable their differentiation for scalable evaluations of drug effects.

Pharmacokinetic variability of beta-adrenergic blocking agents used in cardiology

The aim of this study was to evaluate the pharmacokinetic variability of beta-adrenergic blocking agents used in cardiology by reviewing single-dose and steady-state pharmacokinetic studies from the literature. PubMed was searched for pharmacokinetic studies of beta-adrenergic blocking agents, both single-dose and steady-state studies. The studies included reported maximum plasma concentration (Cmax) and/or area under the concentration curve (AUC). The coefficient of variation (CV%) was calculated for all studies, and a CV% <40% was considered low or moderate variability, and a CV% >40% was considered high variability. The Cmax and AUC were reported a total of 672 times in 192 papers. Based on AUC, metoprolol, propranolol, carvedilol, and nebivolol showed high pharmacokinetic variability (highest first), whereas bisoprolol, atenolol, sotalol, labetalol, nadolol, and pindolol showed low to moderate variability (lowest first). We have shown a high interindividual pharmacokinetic variability that varies markedly in different beta-adrenergic blocking agents; the extreme being steady state ratios as high as 30 in metoprolol. A more personalized approach to the medical treatment of patients may be obtained by combining known pharmacokinetic information about variability, pharmaco-genetics and -dynamics, and patient characteristics, to avoid adverse events or lack of treatment effect.

Antihypertensive drugs

Successful treatment of hypertension is possible with limited side effects given the availability of multiple antihypertensive drug classes. This review describes the various pharmacological classes of antihypertensive drugs, under two major aspects: their mechanisms of action and side effects. The mechanism of action is analysed through a pharmacological approach, i.e. the molecular receptor targets, the various sites along the arterial system, and the extra-arterial sites of action, in order to better understand in which type of hypertension a given pharmacological class of antihypertensive drug is most indicated. In addition, side effects are described and explained through their pharmacological mechanisms, in order to better understand their mechanism of occurrence and in which patients drugs are contra-indicated. This review does not address the effectiveness of monotherapies in large randomized clinical trials and combination therapies, since these are the matters of other articles of the present issue. Five major pharmacological classes of antihypertensive drugs are detailed here: beta-blockers, diuretics, angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, and calcium channel blockers. Four additional pharmacological classes are described in a shorter manner: renin inhibitors, alpha-adrenergic receptor blockers, centrally acting agents, and direct acting vasodilators.

Beta-blocker use and fall risk in older individuals: Original results from two studies with meta-analysis

AIMS

To investigate the association between use of β-blockers and β-blocker characteristics - selectivity, lipid solubility, intrinsic sympathetic activity (ISA) and CYP2D6 enzyme metabolism - and fall risk.

METHODS

Data from two prospective studies were used, including community-dwelling individuals, n = 7662 (the Rotterdam Study) and 2407 (B-PROOF), all aged ≥55 years. Fall incidents were recorded prospectively. Time-varying β-blocker use was determined using pharmacy dispensing records. Cox proportional hazard models adjusted for age and sex were applied to determine the association between β-blocker use, their characteristics - selectivity, lipid solubility, ISA and CYP2D6 enzyme metabolism - and fall risk. The results of the studies were combined using meta-analyses.

RESULTS

In total 2917 participants encountered a fall during a total follow-up time of 89 529 years. Meta-analysis indicated no association between use of any β-blocker, compared to nonuse, and fall risk, hazard ratio (HR) = 0.97 [95% confidence interval (CI) 0.88-1.06]. Use of a selective β-blocker was also not associated with fall risk, HR = 0.92 (95%CI 0.83-1.01). Use of a nonselective β-blocker was associated with an increased fall risk, HR = 1.22 (95%CI 1.01-1.48). Other β-blocker characteristics including lipid solubility and CYP2D6 enzyme metabolism were not associated with fall risk.

CONCLUSION

Our study suggests that use of a nonselective β-blocker, contrary to selective β-blockers, is associated with an increased fall risk in an older population. In clinical practice, β-blockers have been shown effective for a variety of cardiovascular indications. However, fall risk should be considered when prescribing a β-blocker in this age group, and the pros and cons for β-blocker classes should be taken into consideration.

Selective serotonin reuptake inhibitors and β-blocker transformation products may not pose a significant risk of toxicity to aquatic organisms in wastewater effluent-dominated receiving waters

A probabilistic ecological risk assessment was conducted for the transformation products (TPs) of 3 β-blockers (atenolol, metoprolol, and propranolol) and 5 selective serotonin reuptake inhibitors (SSRIs; citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline) to assess potential threats to aquatic organisms in effluent-dominated surface waters. To this end, the pharmacokinetic literature, the University of Minnesota's Biocatalysis/Biodegradation Database Pathway Prediction System aerobic microbial degradation software, and photolysis literature pertaining to β-blockers and SSRIs were used to determine their most likely TPs formed via human metabolism, aerobic biodegradation, and photolysis, respectively. Monitoring data from North American and European surface waters receiving human wastewater inputs were the basis of the exposure characterizations of the parent compounds and the TPs, where available. In most cases, where monitoring data for TPs did not exist, we assumed a conservative 1:1 parent-to-TP production ratio (i.e., 100% of parent converted). The US Environmental Protection Agency (USEPA)'s EPISuite and ECOSAR v1.11 software were used to estimate acute and chronic toxicities to aquatic organisms. Hazard quotients, which were calculated using the 95(th) percentile of the exposure distributions, ranged from 10(-11) to 10(-3) (i.e., all significantly less than 1). Based on these results, the TPs of interest would be expected to pose little to no environmental risk in surface waters receiving wastewater inputs. Overall, we recommend developing analytical methods that can isolate and quantify human metabolites and TPs at environmentally relevant concentrations to confirm these predictions. Further, we recommend identifying the major species of TPs from classes of pharmaceuticals that could elicit toxic effects via specific modes of action (e.g., norfluoxetine via the serotonin 5-hydroxytryptamine [5-HT]1A receptors) and conducting aquatic toxicity tests to confirm these findings. To our knowledge, this is the first quantitative probabilistic ecotoxicological assessment of all of the predicted and probable TPs of these pharmaceuticals, and our approach provides a framework for future such studies with other compound classes as data become available.

Class effect of beta-blockers in survivors of ST-elevation myocardial infarction: A nationwide cohort study using an insurance claims database

Beta-blockers can help reduce mortality following acute myocardial infarction (MI); however, whether beta-blockers exert a class effect remains controversial. This study identified all patients with first ST-elevation MI for the period of 2003 to 2010 from the National Health Insurance claims database, Taiwan. We compared patients prescribed carvedilol, bisoprolol, and propranolol. Study outcomes included all-cause death, cardiovascular death, and recurrence of MI. The propensity scores were constructed using multinomial logistic regression to model the receipt of different beta-blockers. Treating carvedilol group as a reference, we employed a simultaneous three-group comparison approach using the Cox regression model with adjustment for the propensity scores to compare the relative risks of various outcomes. Among the 16836 patients, 7591 were prescribed carvedilol, 5934 bisoprolol, and 3311 propranolol. Mean follow-up time was one year. After accounting for baseline differences, patients treated with bisoprolol (HR 0.87, 95% CI 0.72–1.05, p = 0.14) or propranolol (HR 1.07, 95% CI 0.84–1.36, p = 0.58) had a similar risk of all-cause death in comparison with carvedilol. No significant differences were observed among three beta-blocker groups with regard to the risks of cardiovascular death and recurrence of MI. Our results suggest that beta-blockers exert a possible class effect in the treatment of acute MI.

Managing hypertension in patients with chronic kidney disease

Chronic kidney disease (CKD) and hypertension are intrinsically linked. Although 59% of the US population will be diagnosed with CKD during their lifetimes, mortality is usually due to a cardiovascular event. Sodium restriction and a combination of a renin-angiotensin-aldosterone medication and a calcium channel blocker are the most effective methods of managing hypertension in patients with CKD.

Kidney function and population-based outcomes of initiating oral atenolol versus metoprolol tartrate in older adults

BACKGROUND

Atenolol and metoprolol tartrate are commonly prescribed β-blockers. Atenolol elimination depends on kidney function, whereas metoprolol tartrate does not. We hypothesized that compared to metoprolol tartrate, initiating oral atenolol treatment would be associated with more adverse events in older adults, with the association most pronounced in patients with lower baseline estimated glomerular filtration rates (eGFRs).

STUDY DESIGN

Population-based matched retrospective cohort study.

SETTING & PARTICIPANTS

Older adults (mean age, 75 years) in Ontario, Canada, prescribed oral atenolol versus metoprolol tartrate from April 2002 through December 2011. The 2 groups were well matched (n=75,257 in each group), with no difference in 31 measured baseline characteristics. Patients with end-stage renal disease were ineligible, and 4.6% of patients had chronic kidney disease (median eGFR, 38mL/min/1.73m(2) assessed through a database algorithm).

PREDICTORS

β-Blocker type and eGFR.

OUTCOMES

A composite outcome of hospitalization with bradycardia or hypotension and all-cause mortality were assessed in 90-day follow-up.

RESULTS

Compared to metoprolol tartrate, initiating atenolol treatment was not associated with higher risk of hospitalization with bradycardia or hypotension (incidence, 0.71% vs 0.79%; relative risk, 0.90; 95%CI, 0.80-1.01). Atenolol treatment initiation was associated with lower 90-day risk of mortality than metoprolol tartrate (incidence, 0.97% vs 1.44%; relative risk, 0.68; 95%CI, 0.61-0.74). Lower eGFR did not modify either association (P for interaction=0.5 and 0.6, respectively).

LIMITATIONS

Heart rate and blood pressure were not available in our data sources, and effects ascertained from observational studies are subject to residual confounding.

CONCLUSIONS

Contrary to our expectation, we found that atenolol versus metoprolol tartrate was associated with lower 90-day risk of mortality in patients regardless of eGFR, with no difference in risk of hospitalization with bradycardia or hypotension.

Pharmacologic Issues in treating hypertension in CKD

Antihypertensive drugs are prescribed to patients with CKD to slow down the rate of loss of residual kidney function; to reduce proteinuria, when present; and to protect other target organs from damage that is mediated by elevated blood pressure (BP). In most patients, a diuretic and a renin system blocking drug, such as an angiotensin-converting enzyme inhibitor, angiotensin receptor antagonist, or an aldosterone receptor antagonist are used. Often, 3 or more drugs are needed to achieve BP goals. Many drugs are eliminated through the kidney and in some cases dosage reductions are advisable to avoid adverse effects from high levels of medication. This article will review the various classes of antihypertensive drugs used in the management of high BP in patients with CKD, with an emphasis on pitfalls that arise when kidney function is impaired.

The kidney and hypertension: causes and treatment

Chronic kidney disease is both a cause and a consequence of hypertension. Extracellular volume expansion is an important, if not the most important, contributing factor to hypertension seen in chronic kidney disease. Beyond volume expansion, chronic kidney disease-related hypertension is without truly defining characteristics. Consequently, the sequencing of antihypertensive medications for the patient with chronic kidney disease and hypertension becomes arbitrary. Prescription practice in such patients should be mindful of the need for multiple drug classes with at least one of them being a diuretic. Blood pressure goals in the patient with chronic kidney disease and hypertension are set at lower levels than those for patients with essential hypertension alone. It remains to be determined to what level blood pressure should be lowered in the patient with chronic kidney disease, however.

Blood pressure drug therapy and electrolyte disturbances

Antihypertensive pharmacologic treatment may be associated with diverse disturbances of electrolyte homeostasis. These drug-induced disorders are relatively common, typically including hyponatraemia, hypokalaemia, hyperkalaemia, hypomagnesaemia, hypophosphataemia and hypercalcaemia. Diuretics, beta-blockers, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are particularly likely to cause these complications. Recognised risk factors include high-dosage regimens (especially diuretics), old age, diabetes and impairment of renal function. Strategies to prevent these adverse drug reactions involve careful consideration of risk factors and clinical and laboratory evaluation in the course of treatment.

Use of beta-adrenoceptor antagonists in older patients with chronic obstructive pulmonary disease and cardiovascular co-morbidity: safety issues

The incidence of and mortality from both chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD) increase with age. In addition, the average age of patients with COPD and CVD is also increasing as a result of improvements in both pharmacological and non-pharmacological treatments. Coronary artery disease is a compelling indication for beta-adrenoceptor antagonist use in a population in whom beta-adrenoceptor antagonism is often viewed as contraindicated. beta-Adrenoceptor antagonists have been proven to improve cardiovascular morbidity and mortality but have been under-utilized in patients with COPD with concomitant CVD because of a fear of bronchoconstriction and adverse effects, particularly in the elderly. The advanced age of patients with COPD and CVD, along with the sheer number of patients with these diseases, necessitates that clinicians understand the treatment of these co-morbidities using seemingly conflicting therapy in the form of beta-adrenoceptor agonists and antagonists. We review changes in the pharmacokinetics and pharmacodynamics of beta-adrenoceptor antagonists in the elderly, the role of beta-adrenoceptor antagonists in CVD and the literature regarding the safety and mortality benefits of beta-adrenoceptor antagonists in elderly patients with COPD and concomitant CVD. We conclude that cardioselective beta-adrenoceptor antagonists appear to be safe to use in elderly male patients with mild-to-moderate COPD who have a compelling indication for beta-adrenoceptor antagonist therapy. Data in female patients are very limited. Nonselective beta-adrenoceptor antagonists should be avoided in general, except in patients with heart failure who might benefit significantly from the use of carvedilol. beta-Adrenoceptor antagonists have been shown to improve mortality in older patients with coexisting CVD and COPD.

A review of albumin binding in CKD

Hypoalbuminemia is associated with excess mortality in patients with kidney disease. Albumin is an important oxidant scavenger and an abundant carrier protein for numerous endogenous and exogenous compounds. Several specific binding sites for anionic, neutral, and cationic ligands were described. Overall, the extent of binding depends on the ligand and albumin concentration, albumin-binding affinity, and presence of competing ligands. Chronic kidney disease affects all these determinants. This may result in altered pharmacokinetics and increased risk of toxicity. Renal clearance of albumin-bound solutes mainly depends on tubular clearance. Dialytic clearance by means of conventional hemodialysis/hemofiltration and peritoneal dialysis is limited. Other epuration techniques combining hemodialysis with adsorption have been developed. However, the benefit of these techniques remains to be proved.

Hypertension, Renal Disease, and Drug Considerations

The incidence of chronic kidney disease is steadily increasing in the United States. The magnitude of this problem is such that virtually all health care providers are being called upon to manage these patients. The interplay between chronic kidney disease and drug therapy is complex in that the kidney is both a target for drug effect as well as a moderator of drug elimination. Renal drug elimination occurs by filtration, secretion, and/or metabolism. For renally-cleared compounds, drug clearance typically falls in tandem with the loss of renal function. This process is noteworthy for drug accumulation when the glomerular filtration rate approaches the 30-cc/min range. The kidney is a target for drug effect in relationship to blood pressure and protein excretion. Angiotensin-converting enzyme inhibitor and angiotensin receptor blocker therapy (usually given along with a diuretic) are the drug classes that have been shown to be effective for reduction in both blood pressure and protein excretion in the chronic kidney disease patient. A number of questions still remain unanswered in the pharmacotherapy of chronic kidney disease, including the optimal dose for these drugs as well as what represents the most favorable achieved blood pressure.

The Antihypertensive Efficacy and Safety of a Chronotherapeutic Formulation of Propranolol in Patients With Hypertension

This study evaluated the antihypertensive efficacy and tolerability of a chronotherapeutic formulation of propranolol designed for nighttime dosing (propranolol controlled release [CR]). A total of 434 patients with mild-to-moderate hypertension were randomized to placebo or to one of four doses of propranolol CR (80, 120, 160, or 640 mg/d). At baseline, the mean morning blood pressures were similar in each treatment group and averaged 152/101 mm Hg. After 8 weeks of treatment, morning diastolic blood pressure, the primary efficacy measurement, was significantly reduced from baseline in placebo (-6.98 mm Hg) and all propranolol groups (p<0.001). The decreases ranged from 10.1 mm Hg in the 80-mg/d group to 11.0 mm Hg in the 120-mg/d group and were significantly larger than placebo in the 120-, 160-, and 640-mg/d groups (p<0.05). Blood pressure measured in the evening (trough) demonstrated similar antihypertensive efficacy. Heart rate and rate-pressure product were reduced in a dose-related manner by propranolol CR. The formulation was well tolerated with only fatigue and dizziness being reported more frequently than in the placebo group. Propranolol CR is an effective antihypertensive formulation that may reduce blood pressure during the morning period of maximum cardiovascular risk.

Pathologic Basis and Treatment Considerations in Chronic Kidney Disease-Related Hypertension

Chronic kidney disease (CKD) is both a cause and an effect of hypertension and is multifactorial in its origin. Beyond volume expansion, CKD-related hypertension is without defining characteristics of any consistency. Consequently, the order in which antihypertensive medications are given to the CKD patient with hypertension is arbitrary, although prescription practice is for the most part mindful of the need for multiple drug classes with at least one of them being a diuretic. It is not without reason that blood pressure goals in the hypertensive CKD patient are set at lower levels than those for patients with essential hypertension, but it remains to be determined how much the blood pressure should be decreased in the CKD patient.

Cardiopulmonary bypass alters the pharmacokinetics of propranolol in patients undergoing cardiac surgery

The pharmacokinetics of propranolol may be altered by hypothermic cardiopulmonary bypass (CPB), resulting in unpredictable postoperative hemodynamic responses to usual doses. The objective of the present study was to investigate the pharmacokinetics of propranolol in patients undergoing coronary artery bypass grafting (CABG) by CPB under moderate hypothermia. We evaluated 11 patients, 4 women and 7 men (mean age 57 +/- 8 years, mean weight 75.4 +/- 11.9 kg and mean body surface area 1.83 +/- 0.19 m(2)), receiving propranolol before surgery (80-240 mg a day) and postoperatively (10 mg a day). Plasma propranolol levels were measured before and after CPB by high-performance liquid chromatography. Pharmacokinetic Solutions 2.0 software was used to estimate the pharmacokinetic parameters after administration of the drug pre- and postoperatively. There was an increase of biological half-life from 4.5 (95% CI = 3.9-6.9) to 10.6 h (95% CI = 8.2-14.7; P < 0.01) and an increase in volume of distribution from 4.9 (95% CI = 3.2-14.3) to 8.3 l/kg (95% CI = 6.5-32.1; P < 0.05), while total clearance remained unchanged 9.2 (95% CI = 7.7-24.6) vs 10.7 ml min(-1) kg(-1) (95% CI = 7.7-26.6; NS) after surgery. In conclusion, increases in drug distribution could be explained in part by hemodilution during CPB. On the other hand, the increase of biological half-life can be attributed to changes in hepatic metabolism induced by CPB under moderate hypothermia. These alterations in the pharmacokinetics of propranolol after CABG with hypothermic CPB might induce a greater myocardial depression in response to propranolol than would be expected with an equivalent dose during the postoperative period.

Simultaneous determination of beta-blocking agents and diuretics in doping analysis by liquid chromatography/mass spectrometry with scan-to-scan polarity switching

A previously described method for the screening of 18 diuretics and probenecid was substantially extended with 21 beta-blockers and 8 other diuretics allowing simultaneous determination of diuretics and beta-adrenergic blocking agents in human urine. Analysis was performed using an ion trap instrument with an electrospray ionisation (ESI) interface after liquid/liquid extraction with ethyl acetate. Full-scan MS and full-scan MS2 were applied in combination with scan-to-scan polarity switching. All compounds were separated in less than 22 min. The detection limits for the diuretics were between 5 and 100 ng/mL and for the beta-adrenergic blocking agents were between 5 and 500 ng/mL. The excretion of carvedilol was followed after intake of one tablet of Dimitone. Other doping agents including strychnine, norbuprenorphine and mesocarb hydroxysulfate could also be detected with this method.

Clinical efficacy and safety of telmisartan 80 mg once daily vs. atenolol 50 mg once daily in patients with mild-to-moderate hypertension

The objective of this open-label, parallel-group comparative study was to assess the clinical efficacy and safety of once-daily treatment for 8 weeks with telmisartan 80 mg in comparison with atenolol 50 mg on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in patients with mild-to-moderate hypertension (morning supine SBP 141-199 mmHg, DBP 95-114 mmHg). A total of 58 patients were enrolled. The comparability of the two treatment groups was statistically documented at the beginning of the study. Telmisartan was more effective than atenolol, with a decrease in SBP of 21.7 mmHg vs. 11.8 mmHg (p = 0.03) and a non-significant decrease in DBP of 14.7 mmHg vs. 10.1 mmHg. The safety profiles of both drugs were very similar; both drugs were well tolerated. In conclusion, once-daily telmisartan 80 mg is more effective than once-daily atenolol 50 mg in lowering SBP with no negative chronotropism. Furthermore, telmisartan was as well tolerated as atenolol in the treatment of mild-to-moderate essential hypertension in adults.

A novel potentiometric approach for detection of beta-adrenergics and beta-adrenolytics in high-performance liquid chromatography

Potentiometric approach enabling sensitive and reliable detection for a series of 20 autonomic beta-adrenergic ligands with the use of poly(vinyl chloride) (PVC) based liquid membrane electrode coatings in the normal-bore cation exchange HPLC and narrow-bore reversed phase HPLC system is presented. It was found that in both kinds of HPLC modes with a contemporary hybrid polymer-silica packings an application of electrodes containing a tetrakis(p-chlorophenyl)borate (TCPB) gives limits of detection below to 8.0x10(-7) mol l(-1) (injected concentrations). In case of highly hydrophobic beta-adrenergic drugs the use of binary aqueous mobile phases with high concentrations of acetonitrile (up to 25% v/v) shifting an observable detection limits (DL) down to 2.0x10(-8) mol l(-1), especially for electrodes with addition of trioctylated alpha-cyclodextrin. The characteristics of developed potentiometric detectors was established by proposed a quantitative structure-potentiometric response relationships (QSPRRs) for a series of diversified beta-adrenergic compounds and for a set of the PVC based electrodes using TCPB alone as well as in combination with trioctylated alpha-cyclodextrin, dibenzo-18-crown-6, or calix[6]arene hexaethylester as the neutral macrocycle ionophore. A highly significant QSPRRs equations were obtained leading to reasonable prediction of the DL of specified electrodes in terms of the computationally derived set of molecular descriptors of beta-adrenergics and beta-blocking agents and similar amino alcohol type xenobiotics.