Adrenergic revision 1 of 4
Adrenergic Drugs - Revised Selective α receptor agonists. Eg. Phenylephrine
Adrenergic receptors mediate the effects of NE and Methoxamine (alpha 1), Clonidine (alpha 2)
and epinephrine (Epi). Nonselective β receptor agonist. Eg.
α-Receptors: α1,α2 Isoproterenol
These receptors are found in many tissues Selective β1 agonist. Eg. Dobutamine
α2-Receptors are also found in presynaptic site of Selective β2 agonists. Eg. Metaproterenol,
the adrenergic neuron. Terbutaline, Salbutamol
α1-Receptors are coupled to Gq, whereas α2-
receptors are coupled to Gi/o. Indirect acting
α1-Receptors -mediate many of the classic Drugs inducing release of neurotransmitter. Eg.
effects, originally designated as α-adrenergic Amphetamine, Ephedrine
The α1 and α2 receptors are further divided into Drugs inhibiting reuptake of neurotransmitter. Eg.
α1A, α1B, α1C, and α1D and into α2A, α2B, and Cocaine, Imipramine
α2C. Drugs inhibiting monoamine oxidases. Eg.
Pargyline, Clorgyline
β-Receptors: β1,β2,β3 Drugs inhibiting catechol-o-methyl transferase.
Both β1- and β2-receptors are found in many Eg. Pyragallol
tissues and elicit many different effects
β3-Receptors are found mainly in adipocytes and
some in myocardium. α1 - ADRENERGIC RECEPTOR AGONIST
All three β-receptor subtypes are coupled to Gs. Phenylephrine
It is a direct acting non-catecholamine -has
CLASSIFICATION OF negligible β agonistic and CNS actions.
SYMPATHOMIMETIC DRUGS Chemically differs from adrenaline in lacking 4-
Direct acting (Adrenergic agonists) OH group on the benzene ring.
These are agents that act directly either on alpha It is less potent than nor adrenaline on α1, but has
(alpha1 and alpha 2) or beta (beta1 and 2 ) long duration of action.
adrenoceptors. Pharmacological effects
Drugs having equal potency at α and β receptors. peripheral vasoconstriction -increase in BP
Eg. Epinephrine, Ephedrine, Dopamine It produces reflex bradycardia.
Drugs having higher potency at α receptors. Eg.
Norepinephrine
Adrenergic Drugs - Revised Selective α receptor agonists. Eg. Phenylephrine
Adrenergic receptors mediate the effects of NE and Methoxamine (alpha 1), Clonidine (alpha 2)
and epinephrine (Epi). Nonselective β receptor agonist. Eg.
α-Receptors: α1,α2 Isoproterenol
These receptors are found in many tissues Selective β1 agonist. Eg. Dobutamine
α2-Receptors are also found in presynaptic site of Selective β2 agonists. Eg. Metaproterenol,
the adrenergic neuron. Terbutaline, Salbutamol
α1-Receptors are coupled to Gq, whereas α2-
receptors are coupled to Gi/o. Indirect acting
α1-Receptors -mediate many of the classic Drugs inducing release of neurotransmitter. Eg.
effects, originally designated as α-adrenergic Amphetamine, Ephedrine
The α1 and α2 receptors are further divided into Drugs inhibiting reuptake of neurotransmitter. Eg.
α1A, α1B, α1C, and α1D and into α2A, α2B, and Cocaine, Imipramine
α2C. Drugs inhibiting monoamine oxidases. Eg.
Pargyline, Clorgyline
β-Receptors: β1,β2,β3 Drugs inhibiting catechol-o-methyl transferase.
Both β1- and β2-receptors are found in many Eg. Pyragallol
tissues and elicit many different effects
β3-Receptors are found mainly in adipocytes and
some in myocardium. α1 - ADRENERGIC RECEPTOR AGONIST
All three β-receptor subtypes are coupled to Gs. Phenylephrine
It is a direct acting non-catecholamine -has
CLASSIFICATION OF negligible β agonistic and CNS actions.
SYMPATHOMIMETIC DRUGS Chemically differs from adrenaline in lacking 4-
Direct acting (Adrenergic agonists) OH group on the benzene ring.
These are agents that act directly either on alpha It is less potent than nor adrenaline on α1, but has
(alpha1 and alpha 2) or beta (beta1 and 2 ) long duration of action.
adrenoceptors. Pharmacological effects
Drugs having equal potency at α and β receptors. peripheral vasoconstriction -increase in BP
Eg. Epinephrine, Ephedrine, Dopamine It produces reflex bradycardia.
Drugs having higher potency at α receptors. Eg.
Norepinephrine
