The direct-acting cholinomimetic drugs can be divided on the basis of chemical structure into esters of choline (including acetylcholine) and alkaloids (such as muscarine and nicotine).
A few of these drugs are highly selective for the muscarinic or for the nicotinic receptor. Many have effects on both receptors; acetylcholine is typical.
Cholinomimetic drugCholinomimetic drugsclassify cholinomimetic drugs
Cholinoceptor stimulants
M 、 NR agonist Acetylcholine,ACH
MR agonist Pilocarpine
NR agonist nicotine
cholinesterase inhibitors Neostigmine physostigmine
M,NM,N receptor agonist receptor agonist acetylcholine acetylcholine 乙酰胆碱乙酰胆碱
Pharmacological effects
1 Muscarinic effect
1)cardiovascular system:inhibition
decrease in heart rate (negative chronotropy)
decrease in heart contractility (negative inotropy)
decrease in heart conduction velocity (negative dromotropy)
reduction in peripheral vascular resistance
blood vessels (arteries and veins) dilation (via EDRF)
AcetylcholinAcetylcholin 乙酰胆碱乙酰胆碱Muscarinic effectsMuscarinic effects
2)eye:
miosis, accommodation of focus for near vision
3)glands secretion increase
sweat, salivary, lacrimal, nasopharyngeal
4)smooth muscle : contraction
bronchial muscle ,gastrointestinal tract , urinary bladder detrusor (voiding)
M,NM,N receptor agonist receptor agonist acetylcholine acetylcholine 乙酰胆碱乙酰胆碱
2 nicotinic effect
to excite ganglia
adrenal medulla secrete Adr
cardiovascular system ↑
smooth muscle ↑
glands secretion ↑
neuromuscular junction ↑
M R agonist—PilocarpineM R agonist—Pilocarpine 毛果芸香碱毛果芸香碱
active ingredient of poisonous mushrooms
Pharmacological effects
direct agonist
selectively stimulate muscarinic receptors
M R agonistM R agonistPilocarpinePilocarpine
1 eye:
miosis : sphincter muscle of iris (circular pupillary constrictor muscle) contraction , reduction in pupil size
reduce intraocular pressure :Ciliary muscle contraction puts tension on the trabecular meshwork, opening its pores and facilitating outflow of the aqueous humor into the canal of Schlemn, increased outflow reduces intraocular pressure
M R agonist---Pilocarpine M R agonist---Pilocarpine 毛果芸香碱毛果芸香碱
Clinical uses 1 glaucoma angle-closure glaucoma
type open-angle glaucoma type 2 iritis together with mydriasis drugs
(such as antimuscarinic drugs) , to prevent synechia (adhesion) of iris and lens
3 artropine intoxication
M R agonist---Pilocarpine M R agonist---Pilocarpine 毛果芸香碱毛果芸香碱 toxicity1 Ciliary convulsion (spasm): drops
overdosage2 Depending on absorption: predictable signs
of muscarinic excess ( nausea, vomiting, diarrhea, salivation, sweating, cutaneous vasodilation, and bronchial constriction)
prevention: press the canthus of the eye beside the nose
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