Metoprolol cardiovascular effects

There is strong evidence that beta-blockers can reduce mortality by up to 23% post myocardial infarction. Beta-blockers should be used to reduce the risk of further cardiovascular disease events irrespective of whether the blood pressure is raised or not. There is no evidence that any beta-blocker is more effective than another in secondary prevention, hence a beta-blocker which is well tolerated and that can be taken once or twice daily should be used. Atenolol, bisoprolol or metoprolol are suitable agents. These agents are not specifically licensed post myocardial infarction but all are licensed for angina and the doses for this indication should be used i.e. 

Systemic beta-blockers are used extensively far the treatment of hypertension and other cardiovascular disorders. Of the available oral beta-blockers, atenolol, metoprolol, nadolol, pindolol, propranolol, and timolol have been documented to produce a dose-dependent reduction in lOP. The ocular hypotensive effect associated with systemically administered beta-blockers can be compared with that achieved with topically applied beta-blockers such as timolol. Although specific studies have not been conducted with most of the remaining systemic beta-blockers, these agents might also be expected to reduce lOP at clinically useful doses. 

Viberti GC, Keen H, Bloom SR. Beta blockade and diabetes mellitus effect of o qnenolol and metoprolol on the metabolic, cardiovascular, and hmiuxial re nse to insulin-induced h3fpoglycemia in insulin-dependent diabetics. Metabolism (1980) 29, 873-9. 

Adrenaline (epinephrine) stimulates alpha- and beta-receptors of the cardiovascular system, the former results in vasoconstriction (mainly alphaj) and the latter in both vasodilatation (mainly beta2) and stimulation of the heart (mainly betaj). The net result is usually a modest increase in heart rate and a small rise in blood pressure. However, if the heta-reeeptors are blocked by a non-selective beta blocker, such as propranolol or nadolol (see Table 22.1 , (p.833) for a list), the unopposed alpha vasoeonstrietion causes a marked rise in blood pressure, followed by reflex bradyeardia. Cardioselective beta blockers such as atenolol and metoprolol, whieh are more selective for betaj receptors, do not prevent the vasodilator aetion of adrenaline at beta2 receptors to the same extent, and therefore the effect of any interaction is relatively small. Consequently, adrenaline has been used to assess the degree of beta blockade produced by propranolol and other beta blockers.Phenylephrine is largely an alpha stimulator, therefore beta blockers should have a minimal effect on its action. 

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