Metoprolol [me toe' pro lol]

  • Antihypertensive effects of propranolol are due to

    • (1) Decreased myocardial contractility and rate

    • (2) To consequences of decreased renin secretion.

  • Both effects occur as a consequence of beta-adrenoceptor blockade.

  • Decreased renin levels lead to decreases in circulating angiotensin II and effects on aldosterone levels.

  • Metoprolol is an example of a cardio-selective beta blocker, antagonizing mainly beta-1 receptors.

  • Cardioselective agents also, however, have effects at beta-2 sites and may be relatively contraindicated in certain clinical conditions, such as asthma or chronic obstructive pulmonary disease (COPD).

  • Beta receptor blockade causes:

    • Decreases in myocardial contractility

    • Increases in serum triglycerides and decreases in HDL cholesterol levels

    • Increases in bronchial smooth muscle tone


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