Beta agonists and mnemonic for beta agonists side-effects

In this article we are going to talk about how you can remeber the side-effects of the beta agonists, but before we talk about the mnemonic  first lets breifly know about the beta agonsits that what are beta agonists.

So beta agonists are those drugs which acts on beta receptors present in the body like if we talk about the heart which have B1 receptor so it will be stimulated, in the same case if we talk about the muscles so they are having the B2 receptors.

Responses of β receptors differ from those of α receptors and are characterized by a strong response to isoproterenol, with less sensitivity to epinephrine and norepinephrine  For β receptors, the rank order of potency is isoproterenol > epinephrine > norepinephrine. 

The β-adrenoceptors can be subdivided into three major subgroups, β1 , β2 , and β3 , based on their affinities for adrenergic agonists and antagonists. β 1 receptors have approximately equal affinities for epinephrine and norepinephrine, whereas β 2 receptors have a higher affinity for epinephrine than for norepinephrine. 

Thus, tissues with a predominance of β 2 receptors (such as the vasculature of skeletal muscle) are particularly responsive to the effects of circulating epinephrine released by the adrenal medulla. Binding of a neurotransmitter at any of the three types of β receptors results in activation of adenylyl cyclase and increased concentrations of cAMP within the cell.

Distribution of receptors  

Adrenergically innervated organs and tissues usually have a predominant type of receptor. For example, tissues such as the vasculature of skeletal muscle have both α 1 and β 2 receptors, but the β 2 receptors predominate. Other tissues may have one type of receptor almost exclusively. For example, the heart contains predominantly β 1 receptors.

It is useful to organize the physiologic responses to adrenergic stimulation according to receptor type, because many drugs preferentially stimulate or block one type of receptor. 

 As a generalization, stimulation of α 1 receptors characteristically produces vasoconstriction (particularly in skin and abdominal viscera) and an increase in total peripheral resistance and blood pressure. 

Stimulation of β 1 receptors characteristically causes cardiac stimulation (increase in heart rate and contractility).

whereas stimulation of β 2 receptors produces vasodilation (in skeletal muscle vascular beds) and smooth muscle relaxation. 

β 3 Receptors are involved in lipolysis (along with β1 ), and also have effects on the detrusor muscle of the bladder.

Now lets talk about mnemonic 

Mnemonic for beta agonists side-effects

S to remember the side-effects there are 3Ts  for the side-effects

T=Tolerance
T=Tachycardia
T=Tremors