Alpha-2 adrenergic receptor agonists α2 adrenergic receptor agonists are clonidine, xylazine, Detomidine, Medetomidine and Romifidine are discussed here- Clonidine Clonidine is a partial α2 – adrenergic receptor agonist. Rapid IV injection causes a transient increase in BP due to activation of post junctional α2 receptors in peripheral vascular smooth muscles. However, this effect is followed by a […]

α1 adrenergic receptor agonists α1 adrenergic receptor agonists acts predominantly on α1 adrenergic receptors of animals. here we will see pharmacological effects and pharmacology of these alpha-1 agonists. Pharmacological effects of α1 agonists α1 adrenergic receptor agonists produces peripheral vasoconstriction with resulting increase in BP and small decrease in COP. Trough phenylephrine has no direct effect

Adrenergic agonists Adrenergic agonists are classified into direct acting, mixed acting and indirect acting. these will be discussed here-

Adrenergic receptors Pharmacological effects of adrenergic drugs are mediated by activation of adrenergic receptors. Two types of adrenergic receptors were proposed to explain the dissimilar effects of sympathomimetic agents in different tissues. They are α and β receptors. The α and β receptors are differentiated pharmacologically, initially based on the relative properties of catecholamines namely

Ephedrine Ephedrine is a naturally occurring alkaloid obtained from the Chinese shrub Ephedra vulgaris. It is now synthesized chemically and the clinically used ephedrine is levo form. Mechanism of action It is mixed acting sympathomimmetic which can directly stimulate both α and β receptors and cause release of endogenous nor adrenaline. Pharmacological effects Similar to epinephrine,

Amphetamine Amphetamine is a synthetic sympatho-mimmetic drug with CNS stimulant and peripheral α and β adrenergic actions. Mechanism of action The mechanism of action is indirect, by releasing endogenous noradrenaline from adrenergic nerve terminals. Due to it’s structural resemblance to nor-adrenaline, it is transported into adrenergic nerve terminals by uptake1 process upon entry into the

Isoprenaline (Isoproterenol / Isopropylarterenol) Isoproterenol is a direct acting synthetic catecholamine which predominantly stimulates β1 and β2 receptors. Its main actions are seen on the heart, blood vessels of skeletal muscles and smooth muscles of bronchi and GI tract. It decreases the peripheral resistance and increased blood flow to skeletal muscles, with little effect on

Dopamine (3, 4-dihydroxyphenylethylamine) Dopamine (3, 4-dihydroxyphenylethylamine) is an endogenous catecholamine and immediate precursor of nor adrenaline. Dopamine is a unique catecholamine which has both direct (α and β actions) and indirect (release of nor adrenaline) actions. In addition it also has dopaminergic (D1and D2 receptor actions. The cardiovascular effects of dopamine are mediated by different receptors

Nor-adrenaline or Nor-epinephrine Nor-adrenaline or Nor-epinephrine is the neurotransmitter released by the post ganglionic sympathetic neurons. It also constitutes 10-20% of the catecholamines content of adrenal medulla. Pharmacological effects of Nor-adrenaline or Nor-epinephrine Noradrenaline primarily acts on α1, α2 and β1 receptors and has little action on β2 receptors. Nor adrenaline and adrenaline are equipotent on β1 receptors. However

Adrenaline or Epinephrine Adrenaline or Epinephrine is an endogenous catecholamine and major hormone secreted by adrenal medulla. Commercial preparation is white to off white micro crystalline powder or granules which on exposure to light turns reddish (due to oxidation) with loss of activity. Both endogenous and commercial adrenaline is in levo form which is 15