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68 Cards in this Set
- Front
- Back
Endogenous adrenergic neurotrasmitters belong to this chemical group |
Catecholamines |
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How does termination of the action of NE happen |
1. Diffusion into the circulation 2. Enzymatic biotransformation 3. Re-uptake into the varicosities |
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Enzymatic biotransformation involves the action of |
Monoamine oxidase Catechol-amine methyl transferase |
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Is a mitochondrial enzyme |
Monoamine oxidase |
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Found in soluble fraction of thr cells |
Cathechol-amine amine methyl transferase |
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A prototype sdrenergic stimulant |
Epinephrine |
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5 major effects of epinephrine |
Peripheral excitatory effects - alpha Peripheral inhibitory - beta Cardioexcitatory effect - beta Metabolic effects - alpha and beta CNS effects |
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What are the peripheral excitatory effects |
Vasoconstriction Mydriasis Mucoid and thick salivation |
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What are the peripheral inhibitory effects |
Vasodilation Relaxation of gut smooth muscles Bronchodilation |
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What are the cardioexcitatory effects |
Increased heart rate Increased myocardial contraction |
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What are the metabolic effects |
Hyperglycemia Hyperlipidemia Increased blood lactic acid |
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What are the CNS effects |
Transient respiratory stimulation Wakefulness Anxiety |
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B receptors chiefly in the heart |
B1 |
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B receptors in blood vessels, liver, bronchi |
B2 |
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Alpha receptors present in post synaptic fibers |
A1 |
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Alpha receptors present in both pre and post synaptic fibers |
A2 |
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Have purely direct action or mixed action on the adrenergic system |
Sympathomimetic agents |
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Give examples of endogenous catecholamines |
Epinephrine Norepinephrine |
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Stimulates both alpha and beta receptors |
Epinephrine |
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Mainly an alpha stimulant |
Noepinephrine |
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Pure alpha stimulants |
Phenylephrine Methoxamine Phenylpropanolamine |
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Specific a2 adrenergic stimulants |
Clonidine Oxymethazoline Xylazine Mecetomidine Detomidine |
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Pure beta stimulants |
Isoproterenol Methoxyphenamine |
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Specific b2 adrenergic stimulants |
Clenbuterol Salbutamol Metaproterenol Albuterol Terbulatine |
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Act selectively on b1 receptors, used for cardiac stimulation |
Dobutamine |
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Acts directly on b1 receptors in the heart and on specific dopamine receptors in the CNS |
Dopamine |
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Examples of other directly acting sympathomimetics |
Propylhexedrine Tuaminoheptane Naphazolene Tetrahydrozoline Phenylpropanolamine |
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Used in nasal inhalers |
Propylhexedrine Tuaminoheptane |
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Equal in potency to ephedrine but with less CNS action Used as oral treatment for nasal and sinus congestion |
Phenylpropanolamine |
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Produce their effects by increasing the discharge of NE from varicosities of nerve terminals |
Indirectly acting adrenergic agents |
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Readily enters the CNS and stimulates mood and alertness Eefects can be mediated by release of catecholamines Large doses can induce hallucination |
Amphetamine |
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Large doses of amphetamine can cause |
Hallucination Violent behaviour Psychoses in man |
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Similar to amphetamine but with greater central than peripheral effects |
Metamphetamine |
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Has an action resembling that of ephedrine but lacks CNS stimulant activity Used to treat hypotensive state but principally used as mydriatic |
Hydroxyamphetamine |
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Replace NE from the vesicles and at the same time stimulate adrenergic receptors directly |
Dual acting adrenergic stimulants |
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Occurs naturally in plants but is now synthetically produced Resistant to effect of MAO and COMT enters the brain Affects alpha and beta receptors Commonly used as bronchodilator |
Ephedrine |
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Stereoisomer of ephedrine |
Pseudoephedrine |
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Has both direct and indirect actions Overall effect is similar to norepi but much less potent Principal use is to treat hypotensive state in human |
Metaraminol |
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Pharmacological effects of sympathomimetic agents to vascular smooth muscles |
Vasoconstriction due to alpha receptor stimulation Vasodilation due to beta receptor stimulation |
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Pharmacological effects of sympathomimetic agents to heart |
Increased force of myocardial contraction Increased heart rate Excessive stimulation that lead to arrythmia |
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Pharmacological effects of sympathomimetic agents to blood pressure |
Decrease or increase of bp |
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Pharmacological effects of sympathomimetic agents to bronchioles |
Bronchodilation |
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Pharmacological effects of sympathomimetic agents to spleen |
Contraction of splenic capsule Extrusion of blood |
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Pharmacological effects of sympathomimetic agents to gut |
Inhibition of motility Increased sphincter tone |
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Pharmacological effects of sympathomimetic agents to urinary bladder |
Mild relaxation |
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Pharmacological effects of sympathomimetic agents to uterus |
Cat - relaxation in non gravid uterus but contraction in gravid uterus |
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When b2 agonists are used to relax gravid uterus in cows it is called |
Tocolytics |
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Pharmacological effects of sympathomimetic agents to eyes |
Mydriasis |
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Pharmacological effects of sympathomimetic agents to exocrine glands |
Secretion of thick mucoid saliva Sweating in horse with adrenaline |
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Clinical uses of sympathomimetic agents |
1. Adjunct to local anesthesia 2. As hemostatic 3. As mydriatic 4. In anaphylactic reactions 5. As bronchodilator 6. Treatment of local skin allergy 7. As decongestant 8. For diagnosis of COPD in horses 9. Treatment of cardiac arrest 10. Treatment of hypertensive conditions |
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It causes vasoconstriction and prolongs the effect of local anesthetic |
Epinephrine |
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Drug of choice for anaphylactic reactions because it counteracts hypotension and bronchospasm |
Epinephrine |
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Best treatment for bronchial asthma |
Specific b2 adrenergic agonist |
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Treatment for COPD |
Isoproterenol (IV) |
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When infused slowly it causes vasodilation |
Dopamine |
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Alpha adrenergic blockers |
Phenoxybezamine Dibenamine Phentolamine Prazosin Ergot alkaloids Phenothiazine, butyrophenone tranquilizer Idazoxan, tolazoline, atipamezole, yohimbine |
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Pharmacological effects of alpha adrenergic blockers |
1. Little effect on resting blood pressure 2. Tendency for postural hypotension 3. Little effect on GIT |
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Clinical uses of alpha adrenergic blockers |
1. Used in reversing compensatory vasoconstriction 2. Used to overcome effect of excessive epinephrine |
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Treatment best for shock |
Corticosteroids |
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Used to produce sedation in domestic animal |
Xylazine Medetomidine |
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Pharmacological effect of beta-blockers |
1. Cause cardiac depression 2. Cause bronchoconstriction |
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Beta adrenergic blocking agents |
Dichloroisoproterenol Propanolol Timolol Alprenollol Pindolol Nadalol Sutatol Metoprolol Butoxamine |
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Clinical uses of beta blockers |
1. Treatment of hypertension 2. Reversing digitalis induced cardiac arrythmias 3. Treat obstructive cardiomyopathy 4. Block effect of excessive epinephrine |
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Interference with NE release from vesicles by blocking of nerve action by |
Bretylium Guanethidine |
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Interference with NE re-uptake into varicosities by |
Imipramine Cocaine |
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Interference with NE re-uptake into the dense core vesicles by |
Reserpine Guanithidine |
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Synthesis of false transmitter by ____ & ________ cause hypotension |
a-methyl-DOPA octamine |
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Destruction of adrenergic fibers by _______ produces decreased sympathetic functiom |
6-hydroxydopamine |