Influence of metoprolol CR/ZOK on plasminogen activator inhibitor (PAI-1) in man: a pilot study

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

The effects of nebivolol on fibrinolytic parameters in mild and moderate hypertensive patients

BACKGROUND

The aim of the present study was to investigate the effects of nebivolol (5 mg daily) on plasma levels of hemostatic and fibrinolytic endothelial function markers in mild or moderate hypertensive patients.

METHODS AND RESULTS

Thirty-five (22 female, 13 male; mean +/- SD 54.7 +/- 11.3 years of age) mild and moderate hypertensive patients were included the study. The mean systolic blood pressure [BP] was 160 mmHg (range 150 mmHg to 165 mmHg) and the mean diastolic BP was 100 mmHg (range 90 mmHg to 100 mmHg). Plasma tissue plasminogen activator antigen (tPA-Ag), plasminogen activator inhibitor type 1 antigen (PAI-1-Ag), PAI-1 activity, tPA-Ag/PAI-1-Ag index, fibrinogen and euglobulin lysis time were determined before and after two months of therapy. tPA-Ag and PAI-Ag levels were measured by ELISA. After this period, treatment with nebivolol (5 mg/day) in all patients was associated with a significant decrease in systolic BP and diastolic BP (P<0.001 for each), heart rate (P<0.01), fibrinogen (P<0.005) and euglobulin lysis time (P<0.01). The tPA-Ag and tPA-Ag/PAI-1-Ag index levels were increased significantly (P<0.001 for each) in all patients, but the PAI-1-Ag (P>0.05) and PAI-1 activity (P>0.05) did not show significant change. In the present study, there was no correlation between decreases in arterial BP and decreases in fibrinolytic parameters (P>0.05), but there was a positive, statistically significant correlation between fibrinogen and body mass index (P<0.001).

CONCLUSIONS

The results indicated that, compared with no treatment, a two-month treatment trial with nebivolol was associated with a more favourable modification of hemostatic and fibrinolytic status in addition to antihypertensive effects.

Fibrin D-dimer: a marker of psychosocial distress and its implications for research in stress-related coronary artery disease

Psychosocial factors might mediate their adverse impact on coronary arteries by eliciting a hypercoagulable state via changes in sympathetic nervous system activity. A recent meta-analysis of prospective studies reported an association of the hypercoagulability marker D-dimer with an increased risk for coronary events. This review provides evidence that an elevated plasma D-dimer level is a suitable marker for acute and chronic psychosocial distress. Prospective studies need to show whether stress-related changes in D-dimer may help explain the increased coronary risk with psychosocial distress.

Is the effect of antihypertensive drugs on platelet aggregability and fibrinolysis clinically relevant?

Hypertension is associated with decreased fibrinolytic potential, mainly expressed as elevated plasma plasminogen activator inhibitor type 1 (PAI-1) levels, and increased platelet aggregability, which may account in part for the increased risk of atherosclerosis and its clinical complications in hypertensive patients. The effects of antihypertensive drugs on this prothrombotic state have been investigated and controversial findings have been reported, possibly because of differences in study designs, patients selected, and methodology used. Scarce and conflicting data exist about the effects of diuretics and beta-adrenoceptor antagonists on the fibrinolytic system, whereas ACE inhibitors have generally been reported to improve the fibrinolytic balance by decreasing plasma PAI-1 levels, calcium channel antagonists have been shown to increase tissue plasminogen activator (tPA) activity, and angiotensin II type 1 (AT(1)) receptor antagonists seem to exert neutral effects. beta-Adrenoceptor antagonists, calcium channel antagonists, and AT(1)-receptor antagonists have been reported to exert anti-aggregatory effects on platelets, while contrasting data exist about the influence of ACE inhibitors. Clinical implications of the changes induced by antihypertensive drugs on the fibrinolytic balance and platelet function are still debated. In particular, the question of whether these changes may translate into different degrees of cardiovascular protection in hypertensive patients remains unanswered. While awaiting more information from clinical trials, the choice of antihypertensive drugs, particularly in high-risk patients, should take into account effects beyond their BP-lowering efficacy. Selected agents should have a favorable, or at least neutral, impact on fibrinolytic function and platelet activity.

Effects of psychological stress and psychiatric disorders on blood coagulation and fibrinolysis: a biobehavioral pathway to coronary artery disease?

OBJECTIVE

A hypercoagulable state before overt thrombosis resulting from an imbalance between the coagulation and fibrinolysis systems is related to cardiovascular disease progression and acute coronary syndromes. Psychological stressors and depressive and anxiety disorders also are associated with coronary artery disease. This review explores whether changes in blood coagulation, anticoagulant, and fibrinolytic activity may constitute psychobiological pathways that link psychological factors with coronary syndromes.

METHODS

Literature on coagulation, anticoagulation, and fibrinolysis measures in conjunction with psychological factors (mental stress, psychosocial strain, and psychiatric disorders) was identified by MEDLINE search back to 1966 and through checking the bibliographies of these sources. Sixty-eight articles were critically reviewed.

RESULTS

In healthy subjects, acute mental stress simultaneously activates coagulation (ie, fibrinogen or von Willebrand factor) and fibrinolysis (ie, tissue-type plasminogen activator) within a physiological range. In patients with atherosclerosis and impaired endothelial anticoagulant function, however, procoagulant responses to acute stressors may outweigh anticoagulant mechanisms and thereby promote a hypercoagulable state. Chronic psychosocial stressors (job strain or low socioeconomic status) are related to a hypercoagulable state reflected by increased procoagulant molecules (ie, fibrinogen or coagulation factor VII) and by reduced fibrinolytic capacity. There is also some evidence that points to hypercoagulability in depression.

CONCLUSIONS

Different categories of psychological measures to varying extent are associated with characteristic patterns of coagulation and fibrinolysis activity. Associations between psychological factors and several coagulation and fibrinolysis variables related to atherosclerosis provide a plausible biobehavioral link to coronary artery disease.

Activation of coagulation and fibrinolysis after rehabilitative exercise in patients with coronary artery disease

It has been suggested that blood coagulation be activated and fibrinolytic activity be impaired in patients with coronary artery disease (CAD). With regard to the activation of coagulation and fibrinolysis occurring during exercise in healthy individuals, we examined the hypothesis that rehabilitative exercise in patients with CAD might give rise to an exaggerated activation of coagulation. In 12 patients with angiographically documented CAD without myocardial infarction within the preceding 6 months (male, age 55+/-9 years [SD]) and in 12 healthy controls (male, 52+/-7 years), molecular markers of thrombin, fibrin, and plasmin formation were determined before and after a rehabilitative group exercise session lasting 1 hour. Resting levels of prothrombin fragment 1+2 were lower in patients with CAD (0.67+/-0.2 [SE] vs 1.04+/-0.2 nmol/L, p <0.001) and remained unchanged after exercise, whereas a significant increase was noted in controls (p <0.01). After exercise, plasma levels of thrombin-antithrombin III complexes and of fibrinopeptide A increased significantly in both groups, although there were more pronounced changes in controls. Exercise resulted in a marked generation of plasmin as indicated by plasmin-alpha2-antiplasmin complexes increasing 2.5-fold in patients (p <0.001) and threefold in controls (p <0.001). Repeated experiments in control subjects after administration of aspirin (day 1: 500 mg; days 2 to 5: 100 mg) documented that differences between groups could not be attributed to aspirin medication (100 mg/day) in patients with CAD. We concluded that rehabilitative exercise in patients with CAD beyond the immediate postinfarction period has no detrimental effects on thrombin, fibrin, and plasmin formation.

Fibrinolytic variables and cardiovascular prognosis in patients with stable angina pectoris treated with verapamil or metoprolol. Results from the Angina Prognosis study in Stockholm

BACKGROUND

Disturbed fibrinolytic function may influence the progression of coronary atherosclerosis and contribute to thrombotic cardiovascular (CV) events.

METHODS AND RESULTS

In the Angina Prognosis Study in Stockholm (APSIS), patients with stable angina pectoris were studied prospectively during double-blind treatment with metoprolol or verapamil. Various measures of fibrinolytic function were studied in 631 (of 809) patients. During a median follow-up time of 3.2 years (2132 patient-years), 32 patients suffered a CV death, 21 had a nonfatal myocardial infarction (MI), and 77 underwent revascularization. Plasma levels of tissue plasminogen activator (TPA) activity and antigen (ag), plasminogen activator inhibitor (PAI-1) activity at test, and TPA responses to exercise were determined at baseline and after 1 month's treatment and were related to subsequent fatal and nonfatal CV events. Univariate Cox regression analysis revealed that elevated levels of TPA-ag at rest (P < .05), high PAI-1 activity (P < .05), and low TPA-ag responses to exercise (P < .05) were associated with increased risk of subsequent CV death. After adjustment for baseline risk factors, TPA-ag independently predicted CV death or MI. In addition, PAI-1 activity independently predicted CV death or MI in male patients. Verapamil treatment was associated with a 10% decrease of TPA-ag levels and metoprolol treatment with a 2% increase (P < .001 for treatment difference).

CONCLUSIONS

Plasma TPA-ag levels at rest, and among male patients PAI-1 activity as well, independently predict subsequent CV death or MI in patients with stable angina pectoris.

Metformin and metoprolol CR treatment in non-obese men

OBJECTIVE

To study the effect of metformin and metoprolol CR on insulin sensitivity, blood lipids, fibrinolytic activity and blood pressure.

DESIGN

A double-blind, placebo controlled, triple cross-over study with randomization to either metformin, 850 mg b.i.d., or metoprolol CR 100 mg o.d., or placebo for a period of 18 weeks. The glucose uptake was measured with the euglycaemic clamp technique after every 6 weeks' treatment period. Blood pressure and blood samples were taken every 3rd week.

SUBJECTS

Eighteen non-obese men (53 +/- 6 years of age).

RESULTS

Metformin decreased C-peptide (P < 0.02), FFA (P < 0.003), total and low-density lipoprotein cholesterol, tissue plasminogen activator antigen and the urinary potassium excretion (P < 0.05 for all), but not blood pressure compared to placebo. Metoprolol CR reduced diastolic blood pressure and pulse rate; fasting free fatty acids and the urinary potassium increased (P < 0.05 for all). No effect of metformin or metoprolol CR was seen on the glucose disposal rate, blood glucose, plasma insulin, triglycerides, high-density lipoprotein cholesterol, lipoprotein(a), uric acid or plasminogen activator inhibitor 1 activity or antigen. The glucose uptake was not particularly decreased in these subjects.

CONCLUSION

The study shows that metformin has some favourable effects on metabolism and that metoprolol CR is fairly neutral in this regard. The lack of effect of metformin on glucose disposal rate and blood pressure can be explained by the fact that the individuals studied were neither insulin resistant nor hypertensive. The data does not preclude an antihypertensive effect by treating a concomitant insulin resistance.

Controlled release metoprolol formulations. A review of their pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension and ischaemic heart disease

Conventional formulations of metoprolol have become well established in cardiovascular medicine and are particularly useful in the management of hypertension and ischaemic heart disease. Recently developed controlled release metoprolol delivery systems (metoprolol CR/ZOK and metoprolol OROS) were designed to overcome the drug delivery problems of matrix-based sustained release forms by releasing the drug at a relatively constant rate over a 24-hour period, and thus producing sustained and consistent metoprolol plasma concentrations and beta 1-blockade while retaining the convenience of once daily administration. Clinically and statistically significant reductions in blood pressure have been observed with metoprolol CR/ZOK and metoprolol OROS 24 hours after administration in mildly or moderately hypertensive patients. Studies in patients with mild to moderate hypertension have demonstrated that a similar or higher percentage of patients achieved a goal response with metoprolol CR/ZOK compared with matrix-based sustained release formulations of metoprolol, or conventional atenolol or bisoprolol, while metoprolol OROS achieved an equal or greater response rate compared with conventional or matrix-based sustained release metoprolol preparations. In patients with stable effort angina pectoris, once daily administration of metoprolol CR/ZOK provided at least equal antianginal efficacy as conventional metoprolol in divided doses, while metoprolol OROS reduced the mean number of anginal attacks by the same margin as atenolol. Controlled release metoprolol formulations have been well tolerated in clinical trials. Metoprolol CR/ZOK was associated with a similar or lesser degree of adverse effects related to the central nervous system compared with atenolol or long acting propranolol. Metoprolol CR/ZOK also demonstrated less pronounced beta 2-mediated bronchoconstrictor effects than atenolol in asthmatics, and less general fatigue and leg fatigue in healthy subjects. Metoprolol OROS produced less pronounced bronchoconstrictor effects than atenolol, matrix-based sustained release metoprolol or long acting propranolol in patients with asthma or obstructive airways disease, and healthy volunteers. These results are presumably due to the beta 1-selectivity of metoprolol in addition to the relatively low plasma concentrations maintained by metoprolol CR/ZOK and metoprolol OROS, and the avoidance of high peak plasma concentrations with these agents. Despite the relative safety of the controlled release forms of metoprolol, the use of all beta-adrenoceptor antagonists should be avoided in patients with a history of bronchospasm. Thus, controlled release metoprolol formulations offer the potential to maximise the confirmed benefits of this agent in the management of hypertension and angina, by maintaining clinically effective plasma concentrations within a narrow therapeutic range over a 24-hour dose interval.

Reducing the risk for coronary heart disease and stroke in hypertensives--comments on mechanisms for coronary protection and quality of life

The four most popular classes of antihypertensive drugs may all be considered suitable choices when initiating treatment for hypertension. The practitioner must decide which agent is appropriate for each individual patient. The main goal of treatment should be to prevent coronary events and stroke, while preserving quality of life. A 40% reduction in stroke can probably be achieved with any antihypertensive treatment, a reduction in coronary events is much harder to achieve. Available evidence from studies in men, summarized in this review, indicates that beta-blockade is superior to thiazide diuretics for the prevention of coronary events. Clinical trials have not yet produced long-term prognostic data on the effects of ACE-inhibitors or calcium antagonists on coronary events in hypertensive patients. A recent review on calcium antagonists in post-MI patients concluded that the results were disappointing, as pooled data actually showed a trend towards increased mortality with calcium antagonists as compared with placebo. Because of the large number of hypertensive patients at increased risk for coronary events in the community, the difference observed in coronary events between beta-blockade and other first-line drugs in hypertension (24%) may have important implications for clinical practice. This overall conclusion, however, has to be accepted with some reservations in view of the following observations. Firstly, no reduction in sudden death has been observed with the hydrophilic beta-blockers. Secondly, no reduction in coronary mortality in the smoking subgroup has been observed with the non-selective beta-blockers. Thus, it seems that the prevention of coronary events is more likely to be observed in patients given beta-blockers with certain pharmacological characteristics: relative lipophilicity, which enables passage of the beta-blocker through the blood-brain barrier to exert effects on pertinent central nervous beta 1-receptors. This is potentially useful in reducing the risk of sudden death. The addition of beta 1-selectivity is important for the risk reduction in smokers. Cardioselectivity is also an advantage in relation to side-effects and quality of life. The reduced risk for coronary events with certain beta-blockers is probably independent of the reduction in blood pressure: possible mechanisms studied are cardiac anti-ischaemic effects, antifibrillatory effects, antiatherosclerotic and anti-thrombotic effects.

Controlled release metoprolol. Clinical pharmacokinetic and therapeutic implications

Metoprolol is a relatively beta 1-selective beta-blocker used extensively to treat hypertension and angina and as a prophylaxis after myocardial infarction. Conventional formulations are usually administered twice daily and the drug has a tendency to lose its selectivity of action at higher plasma concentrations. Two controlled release formulations, metoprolol CR and metoprolol 'Oros', have made it possible to achieve sustained beta 1-blockade over an entire 24h period and to minimise the loss of selectivity associated with higher plasma concentrations. The CR formulation has been extensively investigated and is the major subject of this review. The 'Oros' formulation is pharmaceutically different from the CR, yet both produce similar plasma concentration profiles and comparable beta 1-blocking effects. The availability of these preparations occurs at a time when increasingly persuasive data are becoming available on the cardioprotective or coronary preventive action of metoprolol.

Metoprolol versus thiazide diuretics in hypertension. Morbidity results from the MAPHY Study

The present study in hypertensive men (40-64 years old) with untreated diastolic blood pressure above 100 mm Hg was aimed at investigating whether metoprolol (n = 1,609) given as initial treatment would lower the risk for coronary events (sudden death and myocardial infarction) more effectively than thiazide diuretics (n = 1,625). A substantial part of this study was the metoprolol arm of the Heart Attack Primary Prevention in Hypertension (HAPPHY) study. The HAPPHY study was a pooling of the effect of different beta-blockers, mainly metoprolol and atenolol, in which no favorable effect in relative risk was observed for atenolol as compared with diuretics. In the present study, 255 patients suffered definite coronary events during follow-up; 25% of these events were fatal, 39% were acute myocardial infarctions, and 36% were silent myocardial infarctions. The risk for coronary events was significantly lower in patients on metoprolol than in patients on diuretics (111 versus 144 cases, p = 0.001, corresponding to 14.3 versus 18.8 cases/1,000 patient years and a relative risk of 0.76 at the end of the trial; 95% confidence interval 0.58-0.98). This difference in risk has potentially important implications for clinical practice because of the large number of hypertensive patients who are at increased risk for coronary events. Because a placebo group, for ethical reasons, could not be included, relative risk can only be expressed in relation to diuretics. There was no difference between the two treatment groups in baseline characteristics, blood pressure during follow-up, or stroke rates. Thus, the difference in risk for coronary events is probably mediated via mechanisms other than blood pressure control. However, present data might suggest that different beta-blockers may have different efficacy in preventing coronary events. The reasons for this possibility are as yet unknown.