What is the mode of action of beta blockers?

Answer 1

Beta-blockers are drugs that bind to beta-adrenoceptors and thereby block the binding of norepinephrine and epinephrine to these receptors. This inhibits normal sympathetic effects that act through these receptors. Therefore, beta-blockers are sympatholytic drugs. Some beta-blockers, when they bind to the beta-adrenoceptor, partially activate the receptor while preventing norepinephrine from binding to the receptor. These partial agonists therefore provide some "background" of sympathetic activity while preventing normal and enhanced sympathetic activity. These particular beta-blockers (partial agonists) are said to possess intrinsic sympathomimetic activity (ISA). Some beta-blockers also possess what is referred to as membrane stabilizing activity (MSA). This effect is similar to the membrane stabilizing activity of sodium-channels blockers that represent Class I antiarrhythmics.

The first generation of beta-blockers were non-selective, meaning that they blocked both beta1 (b1) and beta2 (b2) adrenoceptors. Second generation beta-blockers are more cardioselective in that they are relatively selective for b1 adrenoceptors. Note that this relative selectivity can be lost at higher drug doses. Finally, the third generation beta-blockers are drugs that also possess vasodilator actions through blockade of vascular alpha-adrenoceptors.

Answer 2

In the UK, the blood pressure association says 140/90, as do the current NICE guidelines above which there needs to be some intervention. Please remember that all the associations and societies have a different view of 'high' and where high begins. My GP says 140/85, it seems to be just pick a number between 75 and 90 . My blood pressure was actually at 192/118 but I had no symptoms as suffered by your husband. I began taking calcium channel blockers which after 3/4 months had reduced my BP but not enough. He wanted me to add another drug to the mix, but I'm really more concerned about him making me sick than my own body. I did some research myself and began taking Hyperexol, a herbal supplement. This is not the cheapest way but as some of the research shows concern that in pre-menopausal oe peri-menopausal women (I'm 47, too) when a second drug is added there is a 17% increase in stroke. Obviously I cannot know if this is drug toxicity or the fact that the BP is out of control but I have such little faith in the medical profession in the UK that I would rather not risk more drugs. Been on Hyperexol for 3 months and BP is generally between 135 to 150 and 80 to 95. Remember it is BP. It does go up and down unless chemically suppressed, I know there aren't too many about round these parts but I need my BP to be able to go up in case the sabre tooth tiger chases me up a tree!! Mostly now, of course, the stress is traffic, doctor's appointments, supermarkets and all the other day to day stuff that whips us up. My body doesn't care if it's the tiger or the carpark, it's doing what nature intended it to do. Cheapest place for Hyperexol if you're interested is to check ebay. It's working for me.

Answer 3

Beta blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. As a result, the heart beats more slowly and with less force, thereby reducing blood pressure. Beta blockers also help blood vessels relax and open up to improve blood flow.

Beta-blockers improve the heart's ability to relax, decrease the production of harmful substances produced by the body in response to heart failure and slow the heart rate. Over time, beta-blockers improve the heart's pumping ability.

Click these links if you would like more information on beta blockers:
http://www.mayoclinic.com/health/beta-blockers/HI00059
http://www.webmd.com/heart-disease/beta-blocker-therapy
http://www.texasheartinstitute.org/HIC/Topics/Meds/betameds.cfm

Answer 4

Beta-blockers work by blocking the action of noradrenaline at special sites (receptors) in arteries and the heart muscle. Noradrenaline is a chemical that transmits messages between nerves and muscles, or between one set of nerves and another. By blocking its action, beta-blockers can cause arteries to widen and can slow the action of the heart and decrease its force of contraction. This results in a fall in blood pressure and reduced work by the heart.
I add a link with details of this subject


http://en.wikipedia.org/
wiki/Beta_blocker

Hope this helps
matador 89

Answer 5

Competitive blockade of beta-adrenoceptors

Answer 6

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