beta blockers are one of the most important classes of medications that are primarily used to treat cardiovascuar disease.
Beta blockers are indicated and have an fda approval to treat tachycardia hypertension myocardial infarction congestive heart failure cardiac arrhythmias as well as hyperthyroidism and even migraine prophylaxis starting with an overview of beta receptors they exist in the body in three distinct forms beta 1 2 and 3. beta 1 is located primarily in the heart
And mediates cardiac activity beta2 however exists throughout the body in many organ systems and controls various aspects of the metabolic activity and induces smooth muscle relaxation beta 3 receptors induce the breakdown of fat cells and are less clinically relevant at presence to understand the mechanism of action of beta blockers we have to understand
How do beta adrenoceptors work in this figure we can see how the heart has both beta1 and beta2 receptors although predominantly beta1 these receptors normally bind to adrenaline or nor adrenaline released from nerve endings or circulating in the bloodstream beta receptors are coupled with gs protein which activates adenylyl cyclase to form camp from atp
Increased camp activates camp dependent protein kinase that phosphorylate l-type calcium channel which causes increased calcium entry into the cells the increased calcium entry during action potential leads to an increase in inotropy and contractility now that we understand how the receptor works it’s easy for us to understand the results of blocking this
Receptor especially in patients with myocardial infarction which results in the relaxation of the heart muscle beta blockers classify as either not selective or beta1 selective non-selective agents bind to both beta1 and beta 2 receptors to induce antagonizing effect examples of a non-selective beta blockers are propranolol carvidolol sotalol and labitolol
Examples however of beta-1 receptor selective blockers like atinolol bisoprolol metoprolol and ismolol only bind to the beta-1 receptors therefore they are also known as cardioselective beta receptors are found all over the body and induce broad range of physiological effects the blockade of these receptors with beta blockers can lead to many adverse effects
Bradycardia and hypotension are two of the most common adverse effects caused by beta blockers fatigue dizziness nausea constipation are also widely reported some patients report sexual dysfunction and erectile dysfunction all beta blockers especially in patients with cardiac risk factors carry a risk of heart block it’s worth mentioning that beta blockers
Are contraindicated in asthmatic patients that’s why it’s recommended that only beta-1 selective beta blockers can be administered to asthmatics do you
Transcribed from video
Beta Blockers Mechanism Of Action [peopranolol, antenolo, bisoprolol, carvedilol] By Pill Whiteboard
