Question

What are the indications and pharmacokinetics for metoprolol?

Answer 1

METOPROLOL

Metoprolol is a beta-blocker that affects the heart and circulation.

Indications

1 Hypertension

2 Angina

3 Acute myocardial infarction

4 Supraventricular tachycardia

5 Ventricular tachycardia

6 Congestive heart failure

7 Migraine heacdaches

Action

Metoprolol blocks adrenergic receptor in heart muscle cells , thereby decreasing the slope of phase 4 in the nodal action potential and prolongingrepolarosation of phase 3. it also work by preventing norepinephrine acting on beta recptors present on heart and in the blood vessels. Thus the blood vessel relax and lowers the heart rate and demand for oxygen.

Pharmacokinetics

Absorption : Metprolole is absorbed over a large part of the intestine and 95% of oral therapetucial dose is generally recorved in urine. pre systematic elimination accounts for about 50% degradation of acutely administered oral doses. The fraction of the dose available systemically may increase up to 70-80% with long term treatment. Food enhances thebioavailability of the drug

Distribution: It distributes very rapidly between blood and extravascular sites. The drug is diffuses readily across the placenta and the concentration in the umbilical and maternal venous blood.About 3-4 fold accmalation can be seen in braetmilk however the adverse reaction is minimal in breastfed child unless the child,s hepatic function is severely underdeveloped.

Metabolism: The metoprol is primarily metabolised by the liver enzyme:CYP2D6.The drug is extensively metabolised and only 5% of an oral dose and10% of an IV dose is excreted in unchanged form through kidneys.

Elimination: Elimination of metoprolol is primarily by biotransformation in the liver. The mean elimination half-life of metoprolol is 3-4 hours and those with poor CYP2D6 has the half life may be 7-9hours. Approximately 95% of oral doses are eliminated through urine. In majority,5%of oral doses and 10% of IV doses are excreted as unchanged.