Adrenergic Receptors

Main groups of adrenergic receptor agonists

With their mechanism of action.

Difference between catecholamine and non catecholamine.

 —Direct acting agents

—

—Indirect acting agent

—

—Mixed acting agent

—Atropine

—Benztropine

—Cyclopentolate

—Darifenacin

—Fesoterodine

—Ipratropium

—Oxybutynine

—Solifenacin

—Tiotropium

—Tolterodine

—Trihexyphenidyl

—Tropicamide

—Trospium chloride

—Scopolamine

—Amphetamines

—Cocaine

—Methylenedioxymethamphetamine (MDMA)

—Tyramine

—Nicotine

—Caffeine

—Methylphenidate

—Mecamylamine

—Ephedrine

—

— Pseudoephedrine

A great number of drugs are available which can affect adrenergic receptors. Each drug has its own receptor specificity giving it a unique pharmacological effect. Other drugs affect the uptake and storage mechanisms of adrenergic cathecholamines and prolonging their action.

—Direct acting agonist bind to adrenergic receptor without  interacting  with  the  precynaptic neuron

    the activated  receptor  initiates synthesis of second messenger (cAMP)  and subsequent   intracellular signals.

    as a group , these agents are widely used clinically :

   1)   epinephrine

   2)  Nor epinephrine

   3)  Isoproterenol

   4) Phenylephrine

 Indirect acting adrenergic agonist cause nor epinephrine release from synaptic terminals or inhibit the reuptake of nor epinephrine, they potentiate the effect of nor epinephrine produced endogenously but these do not directly affect postsynaptic receptors

—Mixed acting drugs induce the release of nor epinephrine from pre synaptic  terminals and they also activate adrenergic receptors on the postsynaptic membrane.

—Mixed acting drugs include:

—Ephedrine

—Pseudoephedrine

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