The document discusses cholinergic neurotransmitters, focusing on acetylcholine's role in the nervous system and its synthesis, receptors, and related pharmacological agents. It covers the classification and mechanisms of action of various cholinergic drugs, including direct-acting agents like acetylcholine and pilocarpine, and indirect-acting cholinesterase inhibitors such as physostigmine and neostigmine. Additionally, it explores the therapeutic uses of these agents in conditions like glaucoma, myasthenia gravis, and xerostomia.

1. Medicinal Chemistry - I
B. Pharma
4th Semester
Unit – 3rd
Prepared by –Nikita Gupta
(Assistant Professor)

2. CHAPTER -1
CHOLINERGIC
NEUROTRANSMITTERS

3. CHOLINERGIC NEUROTRANSMITTER
The neurotransmitter acetylcholine (ACh) is the only
neurotransmitter used in the motor division of the
somatic nervous system and the principal
neurotransmitter at autonomic ganglia.
In the CNS, the neurons that release and respond to
ACh comprise the cholinergic system, which causes anti-
excitatory effects.

4. ACETYLCHOLINE
It is also the preganglionic neurotransmitter for both
the sympathetic and parasympathetic nervous system.
Acetylcholine (ACh) is the postganglionic
neurotransmitter in the parasympathetic nervous system

6. Cholinergic drug, any of various drugs that inhibit,
enhance, or mimic the action of the neurotransmitter
acetylcholine, the primary transmitter of nerve impulses
within the parasympathetic nervous system.
That part of the autonomic nervous system that
contracts smooth muscles, dilates blood vessels, increases
bodily secretions, and slows the heart rate.

7. Cholinergic fibre means
All such fiber that release the acetylcholine as the
neurotransmitter
All the somatic motor neuron to the skeletal muscle
All preganglionic sympathetic and parasympathetic fibre
All the parasympathetic fibre to the neuro- effectors
junction
Post ganglionic sympathetic fibre to sweat gland

8. BIOSYNTHESIS AND CATABOLISM OF
ACETYLCHOLINE
Where are cholinergic neurotransmitters found?
• Acetylcholine is synthesized in certain neurons by the enzyme
choline acetyltransferase from the compounds choline and
acetyl-CoA.
• Cholinergic neurons are capable of producing ACh. An
example of a central cholinergic area is the nucleus basalis of
Meynert in the basal forebrain.

9. Chapter -2
Biosynthesis and
catabolism of acetylcholine

10. Is cholinergic the same as acetylcholine?
• Parts in the body that use or are affected by acetylcholine are
referred to as cholinergic.
• Acetylcholine is also a neurotransmitter in the autonomic
nervous system, both as an internal transmitter for the
sympathetic nervous system and as the final product released
by the parasympathetic nervous system.
• The parasympathetic nervous system, which uses
acetylcholine almost exclusively to send its messages, is said
to be almost entirely cholinergic.

11. What is Acetylcholine?
The first known neurotransmitter, discovered in 1920’s.
It is the neurotransmitter at nerve-muscle connections
and at nervous system synapses.
An organic compound:
CH3 CO2 CH2 CH2N + (CH3)3

12. Synthesis of Acetylcholine (Ach)
• Acetylcholine is a simple molecule synthesized from choline
and acetyl-CoA through the action of choline acetyltransferase
in cholinergic neurons. Acetyl-CoA Choline.
• Acetylcholine is synthesized locally in the cholinergic nerve
endings by the following pathway
• Choline is actively taken up by the axonal membrane by a
Na+: choline cotransporter and acetylated with the help of ATP
and coenzyme-A by the enzyme choline acetyl transferase
present in the axoplasm.

14. • Acetylcholine Synthesis

15. Chapter -3
Cholinergic receptors
(Muscarinic &
Nicotinic) and their
distribution

17. CHOLINERGIC RECEPTORS
-Nicotinic & Muscarinic
1. Nicotinic Receptor [n AChR]
- That bound by the naturally occurring
alkaloid nicotine
- Type of ligand ion channel

18. • Nicotinic receptors :In vertebrates, nicotinic receptors are
broadly classified into two subtypes based on their primary
sites of expression: muscle-type nicotinic receptors and
neuronal-type nicotinic receptors.
• Nicotinic acetylcholine receptors (nAChRs) belong to the
“Cys-loop” superfamily of ligand-gated ion channels that
includes GABAA, glycine, and serotonin (5- HT3)
receptors. There are 16 homologous mammalian nAChR
subunits encoded by a multigene family.

19. What type of receptor is nicotinic receptor?
The nicotinic receptor is a channel protein that, upon binding by
acetylcholine, opens to allow diffusion of cations. The
muscarinic receptor, on the other hand, is a membrane protein;
upon stimulation by neurotransmitter, it causes the opening of
ion channels indirectly, through a second messenger.

20. Nicotinic Receptor

21. 2. Muscarinic Receptor [m AChR]
- That bound by the naturally occurring
alkaloid Muscarinic
- G protein coupled receptor

22. What type of receptor is muscuranic receptor?
• Muscarinic receptors are G-coupled protein receptors
involved in the parasympathetic nervous system.
• The only exception to these receptors is the sweat glands,
which possess muscarinic receptors but are part of the
sympathetic nervous system.
1. Eyes: contraction of ciliary muscle and smooth muscle of the
iris sphincter (miosis)

23. 2. Heart : Bradycardia (possibly preceded by tachycardia),
decrease force of contraction
3. Blood vessel : vasodilation ( EDRF)
4. Lung : bronchoconstriction and increase secretion
5. Pancreas : increased pancreatic juice
6. Urinary bladder : voiding of urine ( detrusor and spincter)
7. Sweat gland : increased sweating

24. • Muscarinic receptors are divided into five main subtypes
M1, M2, M3, M4, and M5. While each of the subtypes
exists within the central nervous system, they are
encoded by separate genes and localized to different
tissue types.
• The M1 receptor is primarily found in the cerebral
cortex, gastric, and salivary glands.

25. Muscarinic Receptor

27. Chapter -4
Structural Activity
Relationship (SAR) of
Parasympathomimetic
Agents

28. Parasympathomimetic Agents
A parasympathomimetic drug, sometimes called a
cholinomimetic drug or cholinergic receptor stimulating agent, is
a substance that stimulates the parasympathetic nervous system
(PSNS).
These chemicals are also called cholinergic drugs because
acetylcholine (ACh) is the neurotransmitter used by the PSNS.
These drugs work by mimicking or modifying the effects of
acetylcholine (ACh), the primary neurotransmitter of the
parasympathetic nervous system.

29. Drugs that activate muscarinic receptors in the peripheral
nervous system are called parasympathomimetic drugs because
they mimic the effects of acetylcholine on the parasympathetic
nervous system.
An example of a parasympathomimetic drug is pilocarpine,
which is a nonspecific muscarinic agonist

30. SAR of Parasympathomimetic agents
• Acetylcholine can exist in a number of conformations. Four of
these conformations are synplanar, synclinal, anticlinal, and
antiplanar.
• The most active isomer is the (+) trans enantiomer and it is
identical to synclinal conformation of acetylcholine.
• The muscarinic receptors and acetylcholinesterase display
stereoselectivity, the (S) enantiomer of methacholine is
equipotent with acetylcholine, while the R (–) enantiomer is
about 20-fold less potent.

32. Classification of Parasympathomimetic Agents
Therapeutic uses:
The drug increases intestinal and bladder motility, which serve
as its therapeutic action in atony of either organ.
Placed topically in the eye, it produces miosis and spasm of
accommodation, as well as a lowering of intraocular pressure.
It is used to treat glaucoma, but pilocarpine is more effective.
Drugs that bind to and activate cholinergic receptors. A
stimulatory alkaloid found in tobacco products that is often used
for the relief of nicotine withdrawal symptoms and as an aid to
smoking cessation.

36. Chapter -5
Direct Acting
agents: Acetylcholine,
Carbachol*, Bethanechol,
Methacholine, Pilocarpine.

37. 1. ACETYLCHOLINE
Acetylcholine: is acetylcholine is an ester of acetic acid and
choline, which acts as a neurotransmitter. It has a role as a
vasodilator agent, a muscarinic agonist, a hormone, a human
metabolite, a mouse metabolite and a neurotransmitter. It is
an acetate ester and an acylcholine.

38. The Mechanism of action of acetylcholine: is as a
Cholinergic Agonist. A neurotransmitter. Acetylcholine in
vertebrates is the major transmitter at neuromuscular
junctions, autonomic ganglia, parasympathetic effector
junctions, a subset of sympathetic effector junctions, and at
many sites in the central nervous system.

39. Uses: Acetylcholine is the chief neurotransmitter of the
parasympathetic nervous system, the part of the autonomic
nervous system (a branch of the peripheral nervous system)
that contracts smooth muscles, dilates blood vessels,
increases bodily secretions, and slows heart rate.

40. 2. CARBACHOL
Carbachol is a parasympathomimetic that mimics the effect of
acetylcholine on both the muscarinic and nicotinic receptors.
This drug is administered ocularly to induce miosis to reduce
intraocular pressure in the treatment of glaucoma.
Carbachol is also used to stimulate micturition by contraction of
detrusor muscle.

41. Mechanism of Action
•Carbachol stimulates both muscarinic and nicotinic
receptors through parasympathomimetic action.
•When it is used in topical ocular or intraocular, it produces
effects like miosis and increased aqueous humor outflow.
Uses:
Miostat (carbachol intraocular solution) is a cholinergic agent
that reduces the pressure in the eye by increasing the amount
of fluid that drains from the eye and is used to treat glaucoma
by lowering the pressure inside the eye.

42. 3. BETHANECHOL
Bethanechol is a Parasympathomimetic choline carbamate
that selectively stimulates muscarinic receptors without any
effect on nicotinic receptors.
Unlike acetylcholine, Bethanechol is not hydrolyzed by
cholinesterase and will therefore have a long duration of action.

43. Mechanism of action:
Bethanechol chloride acts principally by producing the
effects of stimulation of the parasympathetic nervous
system.
It increases the tone of the detrusor urine muscle, usually
producing a contraction sufficiently strong to initiate
micturition and empty the bladder.

44. Uses:
Used to treat certain bladder problems such as the inability
to urinate or empty the bladder completely due to certain
causes
(e.g., surgery, bladder muscle problems).
It works by helping the bladder muscle to squeeze better,
thereby improving your ability to urinate.

45. 3. METHACHOLINE
(INN, USAN) (trade name Provocholine) is a synthetic
choline ester that acts as a non-selective muscarinic receptor
agonist in the parasympathetic nervous system.

46. Mechanism Of Action:
Methacholine chloride is a cholinergic agonist. Bronchial
smooth muscle contains significant parasympathetic
(cholinergic) innervation.
Methacholine chloride agonizes the muscarinic receptors
which eventually induce bronchoconstriction.
Uses: Methacholine is used as a test to determine
whether you may have asthma. It is a cholinergic drug
that causes wheezing and shortness of breath.

47. 4. PILOCARPINE
Pilocarpine is an orally available cholinergic agonist that is
used to treat symptoms of dry mouth in patients with
keratoconjunctivitis sicca (Sjögren syndrome) or with xerostomia
(dry mouth) due to local irradiation.

48. Mechanism Of Action: Pilocarpine hydrochloride is a direct
acting cholinergic parasympathomimetic agent which acts
through direct stimulation of muscarinic receptors and smooth
muscle such as the iris and secretory glands.
Uses: Pilocarpine is used to treat dry mouth caused by
radiotherapy in people with head and neck cancer and to treat
dry mouth in people with Sjogren's syndrome (a condition
that affects the immune system and causes dryness of certain
parts of the body such as the eyes and mouth).

49. Chapter -6
Indirect acting/ Cholinesterase inhibitors
(Reversible & Irreversible): Physostigmine,
Neostigmine*, Pyridostigmine, Edrophonium
chloride, Tacrine hydrochloride, Ambenonium
chloride, Isofluorphate, Echothiophate iodide,
Parathione, Malathion

50. 1. PHYSOSTIGMINE
Physostigmine is a cholinesterase inhibitor used to treat
glaucoma and anticholinergic toxicity.
A cholinesterase inhibitor that is rapidly absorbed through
membranes. It can be applied topically to the conjunctiva.

51. Mechanism Of Action:
Physostigmine acts by interfering with the metabolism of
acetylcholine.
It is a reversible inhibitor of acetylcholinesterase, the enzyme
responsible for the breakdown of acetylcholine in the synaptic
cleft of the neuromuscular junction.
It indirectly stimulates both nicotinic and muscarinic
acetylcholine receptors.

52. Uses:
Physostigmine salicylate has FDA approval for use in the
treatment of glaucoma, as well as the treatment of
anticholinergic toxicity.
It is useful to treat the central nervous system effects of
anticholinergic toxicity due to its ability to cross the blood-
brain-barrier.

53. 2. NEOSTIGMINE
Neostigmine is a cholinesterase inhibitor used in the treatment
of myasthenia gravis and to reverse the effects of muscle
relaxants such as gallamine and tubocurarine. Neostigmine,
unlike physostigmine, does not cross the blood-brain barrier.

54. Mechanism of Action:
Inhibits the hydrolysis of acetylcholine by competing with
acetylcholine for attachment to acetylcholinesterase at sites of
cholinergic transmission. It enhances cholinergic action by
facilitating the transmission of impulses across neuromuscular
junctions.
Uses: Neostigmine is used to improve muscle strength in
patients with a certain muscle disease (myasthenia gravis). It
works by preventing the breakdown of a certain natural
substance (acetylcholine) in your body. Acetylcholine is needed
for normal muscle function.

55. 3. PYRIDOSTIGMINE
Pyridostigmine is a cholinesterase inhibitor used for
symptomatic treatment of myasthenia gravis and congenital
myasthenic syndromes and to reverse neuromuscular blockade
by nondepolarizing muscle relaxants. Brand Names. Mestinon,
Regonol.

56. Mechanism of Action:
Pyridostigmine inhibits acetylcholinesterase in the synaptic
cleft, thus slowing down the hydrolysis of acetylcholine. It
is a quaternary carbamate inhibitor of cholinesterase that
does not cross the blood–brain barrier which carbamylates
about 30% of peripheral cholinesterase enzyme.

57. Uses:
• Pyridostigmine is used to improve muscle strength in
patients with a certain muscle disease (myasthenia
gravis). It works by preventing the breakdown of a
certain natural substance (acetylcholine) in your body.
• Acetylcholine is needed for normal muscle function.

58. 4. EDROPHONIUM CHLORIDE
Edrophonium Chloride is the chloride salt form of
edrophonium, a short and rapid​- acting cholinesterase inhibitor
with parasympathomimetic activity.

59. Mechanism of Action
• Edrophonium works by prolonging the action acetylcholine,
which is found naturally in the body.
• It does this by inhibiting the action of the enzyme
acetylcholinesterase.
• Acetylcholine stimulates nicotinic and muscarinic receptors.
• When stimulated, these receptors have a range of effects.

60. Uses:
• Edrophonium is used as part of a medical test to help diagnose
a muscle disorder called myasthenia gravis.
• Edrophonium is sometimes used to reverse the effects of
certain medications used to prevent muscle contractions during
surgical procedures.

61. 5. TACRINE HYDROCHLORIDE
Tacrine is a member of the class of acridines that is 1,2,3,4
tetrahydroacridine substituted by an amino group at position 9.
It is used in the treatment of Alzheimer's disease.

62. Mechanism of Action
The putative principal mechanism of action of tacrine for
Alzheimer's disease is reversible inhibition of
acetylcholinesterase (AChE), which thereby slows the
breakdown of the chemical messenger acetylcholine (ACh) in
the brain. Tacrine also inhibits butyryl cholinesterase activity.

63. Uses:
Tacrine is an anticholinesterase drug used for the management
of Alzheimer's disease symptoms.
A centrally active cholinesterase inhibitor that has been used to
counter the effects of muscle relaxants, as a respiratory stimulant,
and in the treatment of Alzheimer's disease and other central
nervous system disorders.

64. 6. AMBENONIUM CHLORIDE

65. • Ambenonium chloride is used for the treatment of
myasthenia gravis in patients who do not respond
satisfactorily to neostigmine or pyridostigmine.
• This drug acts by suppressing the activity of AChE. It
possesses a relatively prolonged duration of action and
causes fewer side effects in the GI tract than the other
anticholinesterase agents.
• Because of its quaternary ammonium structure,
ambenonium chloride is absorbed poorly from the GI tract.

66. 7. ISOFLUOROPHATE
Diisopropyl fluorophosphate (DFP) or Isoflurophate is an oily,
colorless liquid with the chemical formula C6H14FO3P. It is
used in medicine and as an organophosphorus insecticide. It is
stable, but undergoes hydrolysis when subjected to moisture.

67. Mechanism of Action:
• Isoflurophate is an organophosphorus compound that acts
as an irreversible cholinesterase inhibitor.
• As such, it displays parasympathomimetic effects.
• Isoflurophate is used in the eye to treat certain types of
glaucoma and other eye conditions, such as accommodative
esotropia.

68. Uses:
• Isoflurophate is used in the eye to treat certain types of
glaucoma and other eye conditions, such as accommodative
esotropia.
• They may also be used in the diagnosis of certain eye
conditions, such as accommodative esotropia.

69. 8. ECHOTHIOPHATE IODIDE
• Echothiophate Iodide is the iodide salt form of echothiophate, a
long-acting cholinesterase inhibitor with parasympathomimetic
activity.
• Echothiophate iodide potentiates the action of endogenous
acetylcholine by inhibiting acetylcholinesterase that hydrolyzes
acetylcholine.

70. Mechanism Of Action
• Echothiophate is an indirect-acting parasympathomimetic
agent. By interfering with the enzymatic destruction of
acetylcholine, echothiophate potentiates the action of
acetylcholine at cholinergic synapses.
• The pupil of the eye is constricted by contraction of the iris
sphincter, producing miosis.

71. Uses:
• Echothiophate iodide ophthalmic (for the eyes) reduces
pressure in the eye.
• This medicine is used to treat chronic open-angle
glaucoma, and other types of glaucoma, especially after
cataract surgery.
• This medicine is also used to treat certain eye-focusing
disorders.

72. 9. PARATHION
Parathion is a deep brown to yellow liquid with a faint odor of
garlic. It is an organic phosphate insecticide which acts as an
inhibitor of cholinesterase, and as such it is highly toxic by all
routes of exposure. It may be found as a liquid or as a dry mixture
where the liquid is absorbed onto a dry carrier.

73. Mechanism Of Action
Parathion is a cholinesterase inhibitor. It generally disrupts
the nervous system by inhibiting acetylcholinesterase. It is
absorbed via skin, mucous membranes, and orally. Absorbed
parathion is rapidly metabolized to paraoxon, as described in
Insecticidal activity.

74. Uses: Parathion is a potent organophosphate pesticide. It is a
pale yellow-to-brown liquid with an odor like garlic. It is used
by farmers as a pesticide on fruits, vegetables, nuts, and
grains. Commercial pesticides often contain a hydrocarbon
solvent, which itself can cause illness.

75. 10. MALATHION
Malathion is a man-made organophosphate insecticide that is
commonly used to control mosquitoes and a variety of
insects that attack fruits, vegetables, landscaping plants, and
shrubs. It can also be found in other pesticide products used
indoors and on pets to control ticks and insects, such as fleas
and ants.

76. Mechanism Of Action
Malathion exerts its action on the nervous system of the lice
by irreversibly inhibiting the activity of cholinesterase,
thereby allowing acetylcholine to accumulate at cholinergic
synapses and enhancing cholinergic receptor stimulation.
This eventually leads to the head lice's death.

77. Uses: Malathion lotion is used to treat head lice (small
insects that attach themselves to the skin) in adults and
children 6 years of age and older. It should not be used in
infants and children younger than 2 years of age. Malathion
is in a class of medications called pediculicides. It works by
killing lice.

78. Chapter -7
Cholinesterase
Reactivators
Pralidoxime chloride.

79. Cholinesterase reactivators
Definition:
A drug used to reverse the inactivation of cholinesterase
caused by organophosphates or sulfonates.
Cholinesterase reactivators (oximes) should be theoretically
effective as an antidote for OP poisoning.
Oximes work by removal of the phosphoryl group from the
inhibited AChE enzyme, resulting in enzyme reactivation.
Pralidoxime (PAM) is the most commonly used oxime
worldwide.

80. What is the function of cholinesterase?
Cholinesterase is a family of enzymes that catalyzes the hydrolysis
of the neurotransmitter acetylcholine (ACh) into choline and acetic
acid, a reaction necessary to allow a cholinergic neuron to return to
its resting state after activation.
• Pralidoxime is a cholinesterase reactivator used to treat
organophosphate poisoning.
• Pralidoxime is an antidote to organophosphate pesticides and
chemicals.
• Organophosphates bind to the esteratic site of acetylcholinesterase,
which results initially in reversible inactivation of the enzyme.

81. Mechanism of action:
The principal action of pralidoxime is to reactivate
cholinesterase (mainly outside of the central nervous system)
which has been inactivated by phosphorylation due to an
organophosphate pesticide or related compound.

82. CHOLINESTERASE REACTIVATORS
1. Pralidoxime chloride
Antidote for poisoning by parathion and related
pesticides.

83. It is an alkaloid obtained from the dried ripe seeds of
Physostigma venenosum.
Physostigmine is a parasympathomimetic, specifically, a
reversible cholinesterase inhibitor which effectively increases
the concentration of acetylcholine at the [(3aR,8bS)-3,4,8b-
trimethyl-2,3a-dihydro-1H-pyrrolo[2,3-b]indol-7-yl] N-
methylcarbamate increases the concentration of acetylcholine at
the sites of cholinergic transmission.
It is a carbamate ester and an indole alkaloid.

84. Chapter -8
Cholinergic Blocking
agents: SAR of
Cholinolytic

85. Definition: Drugs or chemical agents apparently reduce the
number of free receptors( muscarinic and nicotinic)that can
interact with acetylcholine by blocking the active site on
receptor at parasympathetic ganglia or neuro muscular junction
are called as cholinergic blocking agents.
• Cholinergic blocking agents will reduce the availability of
AcH – receptor interactions and its biological response.

86. • Cholinergic blockers are also called as cholinolytics or
para sympatholytics or cholinergic antagonists or
anticholinergics.
• They can also reduce the activity of cholinergic agonistic
drugs.
• Cholinergic blockers are differentiated as muscarinic
blockers and nicotinic blockers

87. SAR OF CHOLINOLYTIC AGENTS
Cationic head (Quaternary N):
• Anti cholinergics containing quaternary nitrogen atom ,shows
stimulative action on muscarinic receptor at neuromuscular
junction in the skeletal muscle. • Drugs should contain quaternary
ammonium like AcH to show cholinergic blocking activity.
• Tertiary amine protonated with positive charge increases the
potency of a drug.
• 10 to 12 carbon bridge between two nitrogens is optimal for
maximum neuromuscular blockade.

88. Chain substitution:
• Bridging structure between two N atoms should be lipophilic
in nature to show increased potency.
• Ester group in the chain provides the most potent
anticholinergic activity. • The substituent may also be ether or
aminoalcohol shows blocking action.
• No substitution in the chain decreases the activity.

89. Substitution at position C:
• The substituent can be hydrogen atom or hydroxyl group
or hyroxymethyl group.
• Antagonist with hydroxyl group or hydroxymethyl group
is more potent.

90. Chapter -9
Solanaceous alkaloids and analogues
Atropine sulphate, Hyoscyamine
sulphate, Scopolamine hydrobromide,
Homatropine hydrobromide,
Ipratropium bromide*.

91. 1. ATROPINE SULPHATE

92. Uses:
1.Atropine produces mydriatic effect (dilation of pupil).
2.Used in the treatment of iritis and corneal inflammations.
3.To treat arrythmias by increasing heart rate.
4. Atropine is used before general anaesthesia to reduce oral
and nasal secretions
5. Used as organophosphate antidote(to prevent muscarinic
effects of AcH accumulation ).

93. 2. HYOSCYAMINE SULPHATE
Uses:
1. Used as a anticholinergic agent.
2.Levorotatory form of atropine H2SO4

94. 3. SCOPOLAMINE HYDROBROMIDE
Uses:
1.Scopolamine is also called as
hyoscine
2.Used to treat motion sickness
and postoperative nausea and
vomiting
3. Scopolamine is used before
surgery to decrease saliva
secretion

95. 4. HOMATROPINE HYDROBROMIDE
Uses:
1. First anticholinergic agent
used before eye
examinations and after eye
surgeries.
2. It blocks muscarinic actions
of acetylcholine
3. It widens the pupil of eye

96. 5. IPRATROPIUM BROMIDE
Uses:
1.Used to control and prevent
symptoms of Wheezing and
shortness of breath caused by lung
disease chronic obstructure
pulmonary disease.
2.It relaxes the muscles around
airways to easier the breathe
3.To treat bronchitis and
emphysema.

97. Chapter -10
Synthetic cholinergic blocking agents
Tropicamide, Cyclopentolate hydrochloride,
Clidinium bromide, Dicyclomine hydrochloride*,
Glycopyrrolate, Methantheline bromide,
Propantheline bromide, Benztropine mesylate,
Orphenadrine citrate, Biperidine hydrochloride,
Procyclidine hydrochloride*, Tridihexethyl chloride,
Isopropamide iodide, Ethopropazine hydrochloride.

98. 1. TROPICAMIDE Uses:
This medication is used to
widen (dilate) the pupil of
the eye in preparation for
certain eye examinations.
It belongs to a class of
drugs known as
anticholinergics.
Tropicamide works by
relaxing
certain eye muscles.

99. 2. CYCLOPENTOLATE HYDROCHLORIDE
Uses:
1. Parasympatholytic
2. It quickly produces
cycloplegia and mydriasis
in the management of iritis
and keratitis
3. It is having spasmodic
activity

100. 3. CLIDINIUM BROMIDE
Uses:
1. Anticholinergic agent
in the treatment of
peptic ulcer,
hyperchlorhydria,
ulcerative colitis and
spastic colon, anxiety
states with GIT
disturbances.

101. 4. DICYCLOMINE HYDROCHLORIDE
Uses:
1.Spasmolytic effect on
various smooth muscle
spasms.
2.Shows neurotropic and
musculotropic effect.
3.Also useful in
dysmenorrhea,
pylorospasm and biliary
dysfunction

102. 5. GLYCOPYRROLATE
Uses:
1.Spasmolytic effect on the
musculature of the GIT and
genitourinary tract.
2.Potent antagonist on M1 receptor
than M2 &M3.
3.Used as adjunct in the treatment of
peptic ulcer associated with
hyperacidity , hypermotility and spasm.

103. 6. METHANTHELINE BROMIDE
Uses:
1.Potent anticholinergic
agents acts on nicotinic
receptor
2.Used to control
gastritis, intestinal
hypermotility , bladder
irritability, pancreatitis,
peptic ulcer,
hyperhidrosis

104. 7. PROPANETHELINE BROMIDE
Uses:
1.More active than
methantheline
2. It shows similar
effects like
methantheline

105. 8. BENZOTROPIUM MESYLATE
Uses:
1.Anticholinergic,antihistam
inic and local anaesthetics
2.Used to treat
parkinsonism
3.Useful in minimizing
drooling, sialorrhea,
oculogyric crisis, muscle
cramps.

106. 9. ORPHENADRINE CITRATE
Uses:
1. Lower antihistaminic property and
higher anticholinergic action
2. This drug is used for the
symptomatic treatment of
parkinsonism disease.
3. It relieves rigidity, mental
sluggishness, akinesia, adynamic
and lack of mobility

107. 10. BIPERIDINE HYDROCHLORIDE
Uses:
1. Biperidine is a
mydriatic drug
2.Used for the
symptomatic treatment
of parkinsonism
(stiffness, tremors
&spasms)

108. 11. PROCYCLIDINE HYDROCHLORIDE
Uses:
1. To treat parkinsonism &
drug –induced parkinsonism
2. To treat acute dystonia,
idiopathic dystonia.
3.It relieves voluntary muscle
spasticity by its central action

109. 12. TRIDIHEXETHYL CHLORIDE
Uses:
1. It possess antispasmodic
and antisecretory activity.
2.This drug is used as
adjunct therapy in peptic
ulcer, GIT disturbances,
spastic colon, gastric
hyperacidity, pylorospasm.

110. 13. ISOPROPAMIDE IODIDE
Uses:
1.It shows Antispasmodic and
antisecretory effect as long as 12
hours per dose.
2.Adjunctive drug in the therapy of
peptic ulcer and other GIT
disturbances associated with
hypermotility and hypersecretion.

111. 14. ETHOPROPAZINE HYDROCHLORIDE
Uses:
1.Antimuscarinic activity
used in the symptomatic
treatment of parkinsonism.
2. One of best anti
parkinsonism drug.

112. MECHANISM OF ACTION
• Cholinergic blockers are competitive antagonists
• They compete with acetylcholine.
• Cholinolytics block acetylcholine at the muscarinic receptors in
the parasympathetic nervous system.
• Reversible blockade of AcH at the muscarinic receptors at
neuromuscular junction occurs by receptor binding with
cholinolytics.

113. Thank You
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