SYMPATHOMIMETICS Classification: A- According to the source: Natural; NE, EP, DA Synthetic; isoproternol, ephedrine, amphetamine B- chemically: Catecholamines; NE, EP, DA and isoproternol Non catecholamines; ephedrine, amphetamine, tyramine

IN DIRECT(MIXED) ACTING drugs α receptor Agonist Selective α2: clonidine Non selective α 1, α2: Phenylephrine Antagonist (blockers) Selective: α1=parzosin, Tamsulosin α2= yohimbine Non selctive α 1, α2: Phenoxybenzamine phentolamine β receptor Agonist Antagonist (blockers) α &β Receptor Agonist Antagonist (blockers) D receptor Agonist IN DIRECT(MIXED) ACTING drugs Agonist ( adrenergic) Increase release of agonist(NE) Work on receptor as agonist (NE) Antagonist (anitadrenergic) False NE >illegal

Non Selective α receptor and blockers α1 α2 Found in Agonist (receptors ) Antagonist (blockers) smooth muscle of many organs ( B.Vs) vasoconstriction increase arterial resistance Selective α1 blockers: (prazosin,Tamsulosin): Vasodilatation Hypotension GIT Decrease motility relaxation Liver glycogenlysis Eye Mydriasis increases the outflow of aqueous humor from the eye Found in Agonist (receptors ) Antagonist (blockers) smooth muscle of many organs ( B.Vs) Selective α2receptors : (clonidine) found postsynaptically : As α1action = Vasoconstriction found presynaptically: platelets aggregation Blocker Selective α2 : (yohimbine) vasodilatation Brain(CNS) Found presynaptically: ( stop release of nor adrenaline) Inhibition sympathetic effect Blocker Selective α2 (yohimbine)= human being :P Increase ( nor adrenaline release ) and cause sympathomimetic effect Pancreas inhibition Insulin secretion Kidney inhibition Renin secretion Non Selective α receptor and blockers Non selective α- receptors: Example: Phenylephrine The bladder base, urethral sphincter and prostate contain α receptors that mediate contraction and therefore promote urinary continence. Non selective α-blockers: Examples: phenoxybenzamine, phentolamine Vasodilatation Reduce blood pressure

Selective &Non Selective β blockers β1 β2 Found in Agonist (receptors ) Respiratory- Lung- bronchodilation peripheral vasodilatation visceral smooth muscle=relaxation skeletal muscle =tremor uterus relaxation that might be useful during pregnancy. (premature labor) LIVER enhances glycogenolysis = increased glucose release into the circulation Mainly By β2 Found in Agonist (receptors ) Antagonist (blockers) Heart Increase: HR (+ve chronotropic effects). cardiac out put (Contractility )= (+ve inotropic effects) selective: β in general ( not β1 ) Examples: Atenolol, metoprolol Reduce : HR (-ve chronotropic effects) force of heart contraction (-ve ionotropic effects) Kidney Renin secretion is stimulated by β1 Selective &Non Selective β blockers Selective Repeated !! Selective β-blockers : Examples: Atenolol, metoprolol Reduce HR (-ve chronotropic) Reduce force of heart contraction (-ve ionotropic) Non Selective β-blockers : Example: Propranolol, labetalol decreases the production of the aqueous humor. These effects are beneficial in treatment of glaucoma. Effect on potassium promotes uptake of potassium into cells, leading to fall in extracellular potassium.. Carbohydrates metabolism in muscle and liver is enhanced

Activation of β3 receptors in fat cells leads to increased lipolysis. Pancreas Insulin secretion is stimulated by β inhibition Insulin secretion α2 Kidney Renin secretion is stimulated by β1 inhibition Renin secretion α2