Side effects of metoprolol
Side effects depend on the individual sensitivity of the patient. , Usually, they are minor and disappear after the drug is discontinued.
From the side of the nervous system: increased fatigue, weakness, headache, slowing of the speed of mental and motor reactions; rarely paresthesia in the extremities (in patients with intermittent claudication and Raynaud’s syndrome), depression, anxiety, decreased attention, drowsiness, insomnia, nightmares, confusion or short-term memory impairment, muscle weakness.
From the senses: rarely – reduced vision, reduced secretion of tear fluid, dry and sore eyes, conjunctivitis, tinnitus.
On the part of the cardiovascular system: sinus bradycardia, palpitation, lowering blood pressure, orthostatic hypotension, dizziness, sometimes loss of consciousness); rarely – decreased myocardial contractility, temporary worsening of symptoms of chronic heart failure (swelling, edema of the feet and / or lower legs, dyspnea), arrhythmias, manifestation of angiospasm (increased peripheral circulatory disturbance, lower extremities cooling, Raynaud’s syndrome), myocardial conduction disturbance, cardialgia .
From the digestive system: nausea, vomiting, abdominal pain, dry mouth, diarrhea, constipation, impaired liver function, taste change.
From the skin: urticaria, skin itch, rash, exacerbation of psoriasis, psoriasis-like skin reactions, skin hyperemia, exanthema, photodermatosis, increased sweating, reversible alopecia.
On the part of the respiratory system: nasal congestion, difficulty exhaling (bronchospasm in high doses – loss of selectivity and in predisposed patients), dyspnea.
On the part of the endocrine system: hypoglycemia (in patients receiving insulin), rarely: hyperglycemia (in patients with diabetes mellitus), hypothyroidism.
Laboratory indicators: rarely – thrombocytopenia (unusual bleeding and hemorrhage), agranulocytosis, leukopenia, increased activity of hepatic enzymes; exceptionally rarely – hyperbilirubinemia.
Influence on the fetus: intrauterine growth retardation, hypoglycemia, bradycardia possible.
Other: pain in the back or joints, like all beta-adrenoblockers in single cases, can cause a slight increase in body weight, a decrease in libido and / or potency.
pharmacologic effect of metoprolol
Metoprolol refers to cardioselective blockers of β-adrenergic receptors, which do not possess internal sympathomimetic activity and membrane-stabilising properties. Has antihypertensive, antianginal and antiarrhythmic action.
Blocking low-dose β-adrenergic receptors of the heart reduces catecholamine-stimulated cAMP production from ATP, reduces the intracellular current of Ca 2+ , has a negative chrono-, dromo-, batmo-, and inotropic effect (reduces the heart rate, inhibits conduction and excitability, reduces contractility myocardium).
The total peripheral resistance at the beginning of the use of β-blockers (in the first 24 hours after oral administration) increases (as a result of the reciprocal increase in α-adrenergic receptor activity and elimination of β-adrenergic receptor stimulation), which returns to the initial one after 1-3 days, appointment – is reduced.
An acute antihypertensive effect is due to a decrease in cardiac output, a stable antihypertensive effect develops within 2-3 weeks. And is due to a decrease in renin synthesis, and plasma renin accumulation, inhibition of renin-angiotensin system activity (important in patients with initial hypersecretion of renin) and CNS restoration of sensitivity baroreceptors of the aortic arch (there is no increase in their activity in response to a decrease in blood pressure). And, as a result, a decrease in peripheral sympathetic Lying. Reduces elevated blood pressure at rest, with physical stress and stress.
The antianginal effect is determined by the reduction in myocardial oxygen demand as a result of a decrease in the heart rate (diastolic elongation and improvement of myocardial perfusion) and contractility, as well as a decrease in myocardial sensitivity to sympathetic innervation. Reduces the number and severity of angina attacks and increases the tolerance of exercise. BP decreases after 15 minutes, maximum – after 2 hours and lasts for 6 hours; diastolic blood pressure changes more slowly: a stable decrease is observed after several weeks of regular intake.
The antiarrhythmic effect is due to the elimination of arrhythmogenic factors (tachycardia, increased activity of the sympathetic nervous system, increased cAMP, arterial hypertension), a decrease in the rate of spontaneous excitation of sinus and ectopic pacemakers, and slowing AV conduction (mainly in the antegrade and, to a lesser extent, retrograde directions via the AV node) and by additional paths. With supraventricular tachycardia, atrial fibrillation, sinus tachycardia in functional heart diseases and hyperthyroidism, it decreases the heart rate or even can lead to the restoration of sinus rhythm. Prevents the development of a migraine.
When used at average therapeutic doses, in contrast to nonselective beta-blockers, it exerts a less pronounced effect on organs containing β-adrenergic receptors (pancreas, skeletal muscles, the smooth musculature of peripheral arteries, bronchi and uterus) and carbohydrate metabolism. When used in large doses (more than 100 mg / day) has a blocking effect on both subtypes of β-adrenoreceptors.