3. DEFINITION
These are the group of drugs which produce
effects resembling those produced by the
stimulation of parasympathetic autonomic
nervous system on the target organs
9. PHOSPHO – INOSITOL SYSTEM
BINDING OF DRUG WITH RECEPTOR
(ALPHA-1 ADRENDERGIC, MUSCARINIC- CHOLINERGIC)
ACTIVATION OF PHOSPHOLIPASE-C
PHOSPHATIDYL INOSITOL 4-5 BIPHOSPHATE
DIACYL GLYCEROL INOSITOL 1.4.5 TRIPHOSPHATE
(CONFINEDTO MEMBRANE) (DIFFUSES INTO CYTOSOL)
ACTIVATION OF PROTEIN KINASEC RELEASE OF Ca++ FROM
INTRACELLULAR SOURCES
ENTRY OF Ca++ THROUGH THE CA++ FORMATION OF Ca++ CALMODULIN
COMPLEX
CHANNEL
ALTERATION IN THE ACTIVITY OF C
DEPENDENT ENZYMES
EFFECT
10. CHOLINERGIC RECEPTORS
Muscarinic
M1 = Nerves, Stomach, Brain
Antagonist: Pirenzepine
M2 = Heart, Nerves, Smooth Muscle.
Antagonist: Gallamine
M3 = Glands, Endothelium, Smooth Muscle.
M4 and M5 newly discovered, role not yet known
24. CARBACHOL
Ester of carbamic acid
Has both muscarinic and nicotinic actions
Muscarinic actions are prominent on eye, GIT &
urinary bladder
DOA more than 30 min
Therapeutic uses:
Glaucoma
25. METHACHOLINE
Has methyl group in its structure
Has both muscarinic and nicotinic actions
(very mild nicotinic actions )
Muscarinic actions are prominent on CVS
Longer DOA as compared to ACh
Therapeutic uses: given SC for the relief
of paroxysmal atrial tachycardia
26. BETHANECHOL
Structure related to Ach, acetate is replaced by
carbamate & choline is methylated
Has no nicotinic actions
Muscarinic actions are prominent on eye, GIT &
urinary bladder
Prolonged DOA
Therapeutic uses:
• Post operative Gastric distension
• Paralytic ileus
• Bladder atonia
27. MUSCARINE
Quaternary amine (Amanita muscaria)
Less complete absorption from the GIT
Very toxic & can even enter the brain
Rx : Atropine
28. PILOCARPINE
Tertiary amine (Pilocarpus jaborandi leaves)
Has muscarinic actions
Therapeutic uses:
• Glaucoma
• To reduce the effect of mydriatics
• To break adhesions
Not used for systemic diseases increased
tracheobronchial secretions leading to
pulmonary oedema
29. NICOTINE & LOBELINE
Plant derivatives
Actions are mainly on nicotinic receptors (CNS,
PNS, NMJ)
CNS, have important effects on brainstem and
cortex.
PNS – autonomic ganglia.
NMJ, immediate depolarization of the end plate
– increase in permeability to Na and K ions.
30. Myasthenia gravis (MG) is a disease affecting skeletal muscle
neuromuscular junctions. An autoimmune process causes
production of antibodies that bind to the a subunits of the
nicotinic receptor. This effect causes accelerated degradation
of the receptor and blockade of ACh binding to receptors on
muscle end plates. Frequent findings are ptosis, diplopia,
difficulty in speaking and swallowing, and extremity weakness.
Severe disease may affect all the muscles, including those
necessary for respiration.
The disease resembles the neuromuscular paralysis produced
by tubocurarine and similar nondepolarizing neuromuscular
blocking drugs. Patients with myasthenia are
sensitive to the action of curariform drugs and other drugs that
interfere with neuromuscular transmission e.g., aminoglycoside
antibiotics. Anti-ChEs are extremely valuable as therapy
for myasthenia. Almost all patients are also treated with
immunosuppressant drugs and some with thymectomy.
Edrophonium is used as a diagnostic test in myasthenia gravis.
31. Diagrams of (A) normal and (B) myasthenic
neuromuscular junctions. The MG junction
has a normal nerve terminal; a reduced number
of AChRs and a widened synaptic space.
32. • In the Alzheimer’s disease in the brain
tissue there are amyloid plaques and
neurofibrillarly tangles, as well as loss
of cholinergic neurons.
• Cholinacetyl trasferase activity
in the cortex and hippocampus
is reduced from 30% to 70%.
• Loss of cholinergic neurons contributes
for to much of the learning and memory deficit.
• The number of M-cholinoceptors is not
affected, but the number of N-receptors
is reduced.