Parasympathomimetic drug are the drugs which mimic the action of Acetylcholine. Here we learn about action of acetylcholine, synthesis of acetylcholine, pharmacological action of acetylcholine, classification of cholinergic drugs

1. PARASYMPATHOMIME
TIC SYSTEM AND
DRUGS
SUBJECT NAME: ADVANCE
PHARMACOLOGY
GUIDED BY : Dr. D. S. SHIRODE
PRESENTED BY : ANKITA S. HALDANKAR
(M. Pharm 1st year Pharmacology)

2. PARASYMPATHOMIMETIC
SYSTEM AND DRUGS
(CHOLINERGIC,CHOLINOMIMETI
C)
PARASYMPATHOMIMETIC /CHOLINERGIC DRUGS are agent
which mimic the effect of Ach
PARASYMPATHOLYTIC/ANTICHOLINERGIC DRUGS are
antagonise the effect of Ach

3. • Acetylcholine is synthesized Locally in the
cholinergic nerve ending
• Immediately after release, Ach is hydrolysed by
the enzyme Cholinesterase And choline is recycled
(Anticholinseterase – AChE or true
Cholinesterase) and (butylcholinesterase or
Pseudocholinesterase) type of enzyme occur in the
body;
• Acetylcholine is not used clinically because
1.It metabolised very quickly by cholinesterase in
plasma and is not effective even by iv route.

4. NEUROTRANSMITTER
• Acetylcholine is principle neurotransmitter in the cholinergic
system.
• Acetylcholine is synthesized locally in the cholinergic nerve
ending.
Acetylcholine is quaternary ammonium compound and it is
rapidly hydrolysed by cholinesterase hence no therapeutic
application.
Steps in neurohumoral transmission
1.Impulse conduction
2.Transmitter release
3.Transmitter action on post junctional membrane
4.Post junctional activity
5.Termination of transmitter action

9. PHARMACOLOGICAL ACTION OF ACETYLCHOLINE
• Acetylcholine produces muscarinic and nicotinic effect by interacting with
respective receptor on the effector cells
(A)MUSCARINIC ACTION
1. CARDIOVASCULAR SYSTEM
(a) Heart : Ach by stimulating M2 receptor of the heart,opens K+ channel resulting
in hyperpolarizations. Therefore S-A and A-V nodal activity is reduced.
• Decrease heart rate(negative chronotropic effect)
• Decrease Force of contraction( negative inotropic effect)
• Decrease AV conduction (negative dromotropic effect)
2. SMOOTH MUSCLES
(a) Gastrointestinal tract :
• Increase tone of the gut
• Increase peristaltic movement
• Increase GI Secretions

10. 3 GLANDS :
• Increase glandular secretion
• Increase salivation
• Increase Lacrymation
4. EYE :
• Contraction of circular muscle of iris (Miosis)
5. MALE SEX ORGAN :
• Due to vasodilation cholinergic system is responsible for erection of
male organ
(B) NICOTINIC ACTION
1.AUTONOMIC GANGLIA :
Both parasympathetic and sympathetic ganglia are stimulated by Ach
through the stimulation of Nn receptor
2. NEUROMUSCULAR JUNCTION :
Ach stimulate skeletal muscle contraction by action on Nm receptor.

12. DIRECTLY ACTING PARASYMPATHOMIMETIC
DRUGS
• NATURAL ALKALOID :
Acetylcholine, Muscarine, Nicotine, Pilocarpine,Arecholine.
• SYNTHETIC DERIVATIVE :
Methacholine, Carbachol, Bethanechol
1. PILOCARPINE : Pupil – M3 receptor
• Obtained from pilocarpus plant mainly used for glaucoma
• Occusert is a sustained delivery system of pilocarpine.
2. BETHANECHOL : Bladder – M3 receptor
• Used for treatment of urinary retention

13. INDIRECTLY ACTING PARASYMPATHOMIMETIC DRUGS
• These drugs act by inhibiting the enzyme
acetylcholineesterase, thus prolonging the action of Ach.
• These drugs are also called anticholinseterase.
• Anticholinseterase may be reversible or irreversible.
1. Reversible :
Physostigmine, Neostigmine, Pyridostigmine, Endrophonium,
2. Irreversible :
Dyflos, echothiophate, Carbaryl
A. Physostigmine – (Eserine)
• It is an alkaloids obtained from Physostima Venenosum
• Lipid soluble tertiary amine derivative.
• In eye cause miosis so used in glaucoma

14. 2. NEOSTIGMINE :
• It is a synthetic anticholinseterase agent
• Quaternary ammonium compound.
• Used in postoperative retention, myasthenia gravis, curare
poisoning.
3. EDROPHONIUM :
• Quaternary ammonium compound.
• Suitavle as a diagnostic agent for myasthenia gravis.
• Edrophonium is a shortest acting cholinesterase inhibitor.
4. TACRINE :
• Drug of choice for Alzheimer disease.
• It cause hepatotoxicity so it is baned.
• Now preferd drugs are – Donepezil, Rivastigmine,
Galantamine.

15. THANK YOU