Drug & Type (e.g. ACh agonist)
Clinical Use
Pharmacodynamics (mechanism of action)
PILOCARPINE (alkaloid)- (Partial Muscarinic AChR agonist)
In ophthalmology as a treatment for glaucoma (^ ocular pressure).
Causes constriction of sphincter pupillae (circular muscle) (i.e. pupil constricts) for aqueous humour drainage via canals of Schlemm.
BETHANECHOL (choline ester)(M3 AChR selective agonist)
To assist bladder emptying and gastric motility.
NEOSTIGMINE/ PHYSOSTIGMINE (reversible anticholinesterases, competitive inhibitor of AChE against ACh, thus preventing ACh degradation)
Treatment of glaucoma, aiding intraocular fluid drainage. Treatment of ATROPINE (potent Muscarinic antagonist) poisoning esp. in children.
Compete with ACh for active site of acetylcholinesterase (AChE). Donate a carbamyl group to the enzyme which prevents ACh from binding. Carbamyl gp is removed by slow hydrolysis (lasting minutes not ms), leading to an ^ duration of ACh activity in the synapse.
Pharmacokineti cs (passage throughout the body) T ½ = 3 to 4 hrs.
Side effects
Blurred vision, sweating, GI disturbance & pain, hypotension, respiratory distress.
Not a substrate for acetylcholinestera se, PHARM S3 L6.
T ½ = 3 to 4 hrs.
Sweating, impaired vision, nausea, bradycardia (M2), hypotension, respiratory difficulty.
T ½ = 30 mins.
Low doses: excitation with possibility of convulsions. High doses: unconsciousness, respiratory depression, death. NB: at high doses all anticholinesterases can cause increased transmission of ACh at ALL (PNS & SNS) autonomic ganglia.
Resistant to degradation, orally active, limited access to brain. PHARM S3 L6. Only non-polar organophosphate s (e.g. PHYSOSTIGMINE) can cross the Blood-Brain Barrier (BBB). PHARM S3 L6.
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Contraindications
Extra Information (e.g. similar drugs)