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Autonomic nervous system pharma..


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Pharmacology of Autonomic Nervous System

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Autonomic nervous system pharma..

  1. 1. AUTONOMIC NERVOUSSYSTEMSaddam AnsariTbilisi State Medical University
  3. 3. ObjectivesSympathomimetic drugs (drugs that act onadrenergic effector organs )• Drugs that cause release of norepinephrine from nerveendings• Drugs that block adrenergic activityDrugs that act on cholinergic effector organs• Parasympathomimetic drugs
  4. 4. Continued…• Drugs that have a parasympathetic potentiating effect –Anticholinesterase drugs• Drugs that block cholinergic activity at effector organ –Antimuscarinic drugsDrugs that stimulate or block sympathetic andparasympathetic postganglionic neurons• Drugs that stimulate autonomic postganglionic neurons• Ganglionic blocking drugs
  5. 5. Sympathomimetic DrugsDrugs that acts like sympathetic stimulationCauses same effectThere are many drugs• E.g. norepinephrine, epinephrine, methoxamineThese drugs differs from one another with respect to• Degree to which they stimulate different sympatheticeffector organs• Duration of action
  6. 6. Continued…• Epinephrine and norepinephrine have actions only 1 to 2minutes• Whereas the actions of other commonly usedsympathomimetic drugs lasts for approximately 30minutes to 2 hours
  7. 7. Continued…Important drugs that stimulate specific adrenergicreceptors are• Phenylephrine – alpha receptors• Isoproterenol – beta receptors• Albuterol – only beta2 receptors
  8. 8. Drugs That Cause Release ofNorepinephrineIndirect sympathomimetic actionThese drugs include• Ephedrine• Tyramine• AmphetamineThese drugs releases norepinephrine from itsstorage vesicles in the sympathetic nerve endings.
  9. 9. Drugs That Block Adrenergic Activity• Synthesis and storage of norepinephrine in thesympathetic nerve endings can be prevented. Best knowndrug is RESERPINE• Release of norepinephrine from the sympathetic endingscan be blocked by GUANETHIDINE• Sympathetic alpha receptors can be blocked byPHENOXYBENZAMINE and PHENTOLAMINE
  10. 10. Continued…• The sympathetic beta receptors can be blocked. Drug thatblocks all beta receptors is PROPRANOLOL andMETAPROLOL blocks only beta1 receptors• Sympathetic activity can be blocked by drugs that blocktransmission of nerve impulses through autonomicganglia. E.g. HEXAMETHONIUM
  11. 11. Parasympathomimetic DrugsAlso known as Cholinergic DrugsThese drugs are not rapidly destroyed bycholinesteraseDrugs• Pilocarpine• MethacholineAct directly on muscarinic receptors
  12. 12. Continued…Also act on the effector organs of cholinergicsympathetic fibers and causes:• Profuse sweating• Vascular dilatation
  13. 13. Anticholinesterase DrugsIt has parasympathetic potentiating effectDrugs:• Neostigmine• Pyridostigmine• Ambenonium
  14. 14. Antimuscarinic DrugsBlocks cholinergic activity at effector organsDrugs:• Atropine• Homatropine• ScopolamineDoesn’t effect on nicotinic action
  16. 16. Stimulation of Autonomic PostganglionicNeurons• Acetylcholine (injected) can stimulates postganglionicneurons of both systems• Causes sympathetic and parasympathetic effectsimultaneously• Nicotine has also causes same effect
  17. 17. Ganglionic Blocking DrugsBlocks impulse transmission from thepreganglionic neurons to the postganglionicneuronsDrugs:• Tetraethyl ammonium ion• Hexamethonium ion• PentoliniumThese drug’s effects are difficult to control –notvery useful clinically