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ans lecture 4new

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ans lecture 4new

  1. 1. Na + Ca 2+ Acetylcholinesterase Pharmacologic manipulation of the cholinergic system Presynaptic neuron Postsynaptic target Nicotinic Receptor Muscarinic Receptor Choline Choline Na + Acetyl CoA + Acetylcholine Choline Acetyltransferase H + ACH ACH Choline Acetate Action Potential   
  2. 2. Direct acting cholinergic receptor agonists: Esters C H 3 C H 3 H 2 N C a r b a c h o l ( I s o p t o c a r b a c h o l ) C O H 3 C O C H C H 2 N C H 3 C H 3 C H 3 M e t h a c h o l i n e C H 3 (Provocholine) C O H 3 C O C H 2 C H 2 N C H 3 C H 3 C H 3 A c e t y l c h o l i n e ( M i o c h o l ) C O O C H C H 2 N C H 3 C H 3 C H 3 H 2 N C H 3 B e t h a n e c h o l ( U r e c h o l i n e ) C O O C H 2 C H 2 N C H 3
  3. 3. Direct acting cholinergic receptor agonists: Alkaloids and synthetic analogs N C H 3 N N i c o t i n e ( N i c o r e t t e ) O O C H 2 H 2 C H 3 C N N C H 3 P i l o c a r p i n e ( I s o p t o c a r p i n e ) O H H H 3 C H O H N ( C H 3 ) 3 ( + ) - M u s c a r i n e
  4. 4. Receptor agonists activate signal transduction pathways M 3 muscarinic receptor C O O C H 2 C H 2 N C H 3 C H 3 C H 3 C H 3 Acetylcholine NH 3 COOH G q Phospho - lipase C (+) PIP 2 IP 3 Diacylglycerol Increase Ca 2+ Activate Protein Kinase C Response
  5. 5. Molecular actions of acetylcholine at muscarinic receptors I II IV V VI VII III Asp105 Thr189 Tyr381
  6. 7. Stereochemistry of cholinergic drugs + Acetylcholine + trans cis
  7. 8. Stereochemistry of cholinergic drugs O H H H 3 C H O H N ( C H 3 ) 3 O H N ( C H 3 ) 3 O H 3 C H 3 C O C H 3 N ( C H 3 ) 3 O H 3 C H (+)-muscarine (+)-methacholine (-)-methacholine
  8. 9. Stereochemistry of cholinergic drugs O H H H 3 C H O H N ( C H 3 ) 3 O O N H N H 3 C (+)-muscarine Protonated pilocarpine
  9. 10. Stereochemistry of cholinergic drugs (+)-muscarine Protonated pilocarpine
  10. 11. Nicotine pKa 6.16 pKa 10.96 <ul><li>Dibasic </li></ul><ul><li>Nicotinic receptors less stereoselective </li></ul>
  11. 12. Varenicline tartrate (Chantix) <ul><li> 4  2 Nicotinic receptor partial agonist </li></ul><ul><li>Activates nicotinic receptor much less than nicotine; Blocks nicotine from binding </li></ul><ul><li>Well tolerated </li></ul><ul><li>Side effects: </li></ul><ul><ul><li>GI related (nausea, constipation, gas, vomiting) </li></ul></ul><ul><ul><li>Altered dreams </li></ul></ul>
  12. 13. Clinical pharmacology of cholinergic receptor agonists Drug Receptor Cholinesterase Sensitivity Clinical Use Acetylcholine M, N Yes Intraocular use for miosis during surgery Carbachol M, N No Intraocular use for miosis during surgery, glaucoma Pilocarpine M No Glaucoma Bethanechol M No Urinary retention, post-operative ileus M=Muscarinic N=Nicotinic Why are antimuscarinic drugs contraindicated in glaucoma? Varenicline N No Smoking cessation

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