PHARMACOLOGY GPAT-2019- ADRENERGIC AGONISTS
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Drug
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Action
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Receptor
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Therapeutic Uses
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Pharmacokinetics
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Adverse Effects
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Other
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Epinephrine (Direct)
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-at low doses, β effects on the vascular system (vasodilatation)
-at high doses, α effects are stronger
(vasoconstriction)
-Strengthens the contractility of the myocardium and increases the rate of contraction (β1)
-constricts arterioles in the skin, mucous membranes and viscera (α effects) -dilates BV to liver and skeletal muscle (β2)
-Increase in systolic pressure, decrease in diastolic pressure -Bronchodilation (β2)
-Inhibits the release of allergy
mediators
-Increased glycogenolysis in the liver, increased release of glucagon (β2 effect)
-decreased release of insulin (α2 effect)
-initiates lipolysis (β receptors)
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α and β
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-DOC in: acute asthma,
anaphylactic shock -Open-angle glaucoma (2% soln topically) -Restore cardiac rhythm in patients with cardiac arrest
-Used in combination with local anesthetics to increase the duration of the anesthesia -Weak solutions can be used topically to control oozing of capillary blood
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-rapid onset, but brief duration of action
-can be given IV, SC, endotracheal tube, inhalation, topically to eye
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-CNS: anxiety, fear, tension, headache, tremor
-Cerebral hemorrhage
-Cardiac arrhythmias, particularly in
patients on digitalis
-Pulmonary edema
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-catecholamine
-synthesized from dopamine in the adrenal medulla -metabolized by COMT and MAO; final metabolites in urine
are metanephrine, vanillylmandelic acid -rather than epinephrine, β2 agonists like ALBUTEROL are favoured in chronic Tx of asthma -enhanced CV action in pts with hyperthyroidism
-exaggerated CV response in presence of cocaine
-in diabetics, if epi is being used, insulin may have to be increased -β-blockers block effect of βreceptors, leaving α-receptors unopposed (increase in BP) -inhalation anesthetics sensitize the heart to effects of epinephrine
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Norepinephrine/
Levarterenol
(Direct)
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-vasoconstriction of most vascular beds causing rise in peripheral resistance -systolic and diastolic pressure increases -if ATROPINE blocks transmission of vagal effects before giving NE, stimulation of heart causes tachycardia -increased force of contraction in the heart (+ve ionotropic effect)
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αreceptors
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-Shock
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-IV
-Duration of action 1-2 minutes at the end of the infusion period
-poorly absorbed with SC injection
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-Similar to epinephrine -Blanching and sloughing of skin along injected vein
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-catecholamine
-METARAMINOL preferred over NE for shock because it doesn’t reduce blood flow to kidneys like NE
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Isoproterenol (Direct)
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-increases rate and force of contraction of the heart
-Dilates arterioles of skeletal muscle, resulting in decreased peripheral resistance (β2 effect)
-slight increase in systolic pressure, but
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β1 and β2 receptors
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-AV block
-Cardiac arrest -Acute asthma attack (inhalation)
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-Sublingual
-Parenterally
-Inhaled aerosol
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-similar to epinephrine
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-synthetic catecholamine -stable to MAO, minor substrate for COMT
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