Blockade of cholinergic receptors

• Muscarinic Antagonists

  • Competitively block muscarinic receptors: parasympatholytics

  • Examples belladonna alkaloids atropine and scopolamine

  • Scopolamine can cross BBB better than atropine

  • Effects: relax nonvascular smooth muscle, including lung airways, GI tract, and urinary bladder. Inhibit secretion of substances from various exocrine glands causing xerostomia. If they can cross BBB will interfere with short term memory and may cause delirium, excitement, agitation, and toxic psychosis.

• Ganglionic Blocking agents

  • Will block both sympa and para

Cholinomimetics:

• Quaternary ammoniums agonists do not penetrate BBB and are poorly absorbed orally

• Tertiary ammines cross BBB

• Highly lipophlic organophosporous cholinesterase inhibitors well absorbed from GI tract, lung, eyes and skin: VERY DANGEROUS

Cholingeric Blocking drugs:

• Lipophilicity and degree of ionization will determine their absorption and distribution

Category: Pharmacology Notes