Beta Adrenergic blocking drugs l Study Pharma l

Beta blockers:
Beta adrenergic blocking drugs are those drugs which act by inhibiting the response mediated through beta receptors without affecting that response mediated through alpha adrenergic receptors.

Pharmacological action of Beta blockers:
Cardiovascular system (CVS):
1. Heart:
- Decrease in heart rate due to blocked of beta 1 receptors by beta blocking agents, in results suppresses the cardiovascular system.
- Force of contraction and cardiac output reduced
- Cardiac work and oxygen consumption is reduced

2. Blood vessels:
- Beta blockers blocks the beta 2 receptors that have inhibitory innervation to cause vasodilation, ultimately vasoconstriction occur.
- No marked effect on BP because of already decreased in cardiac output.
Further mechanism like:-
- Reduced in renin release from kidney by blocking of beta 1 response mediated by beta 1 receptors.
- Reduced in noradrenaline release by blocking of beta 1 response mediated by beta 1 receptors.

Respiratory tract:
- Constriction of bronchial muscles occur due to blocked the beta 2 receptors response.

Central nervous system (CNS):
- No marked effect observed but some behavioural changes, forgetfulness, increasing dreaming like nightmare when takin dose for longer periods.

Metabolic:
- Reduced lipolysis
- Plasma free fatty acids, LDL/HDL ratio increases during propranolol therapy (Beta blocker).

Skeletal muscles:
- Beta blockers produce effect on skeletal muscles peripherally.
- Reduced exercise capacity by blocking beta action which reduced in lipolysis.