Non selective Beta
pharmacological action of (Propranolol ,
Nadolol , Timolol , Pindolol)
Pharmacological action :
On the heart:
It is useful for people who have a weak
heartbeat and bradycardia, in addition to pressure patients .
On the blood vessels:
- it closes the beta receptors in the skeletal muscles, which leads to the constriction of the blood vessels in the skeletal muscles, so the patient have a reflexe tachycardia .
- When a sharp decrease in blood pressure occurs, the heart takes blood from what is in the aorta. A tachycardia reflex occurs, and the brain sends a signal to activate the sympathetic and increase the amount of blood heading towards the heart.
On the kidneys:
they have beta 1 receptors, and they usually
supply the exit of urine outside the body, when they block angiotensin, it
leads to contraction.
On the lung:
it contains beta-2 receptors, so it is not
useful to give this type of medicine to patients with pressure and crisis .
On the glucose :
Beta-blockers affect blood sugar by
lowering it because they reduce the rate of glycogenolysis and the release of
glucagon from the pancreas to the liver for glucose manufacture.
On lipids :
Non-selectivity affects fats in the blood, as it leads to an
increase in the level of harmful fats and harmful cholesterol ( LDL ,
triglycerides) , on the other hand, a decrease in the amount of beneficial fats
( HDL increase ) (fats were burned and fats became energy when stimulated) here
the main reason is to block beta-3 receptors .
There are no drugs that are selective on beta 2 or beta 3, while there is beta 1 selectivety. Why?
- For example, beta 2 is found in the airways, so its closure will lead to bronchospasm.
- As for beta 3, it is found in the urinary bladder and urethra, which leads to sexual dysfunction, in addition to affecting the lipids in the blood, as it reduces the beneficial and increases the harmful, etc.