The document discusses the autonomic nervous system and autonomic drugs. It describes the parasympathetic nervous system in detail. The parasympathetic nervous system uses acetylcholine as its neurotransmitter and has effects such as reducing heart rate and blood pressure and facilitating digestion. Drugs that act on the parasympathetic nervous system are cholinergic agents, which mimic acetylcholine, and anticholinergic agents, which block acetylcholine's effects. Cholinergic drugs include acetylcholine and are used to treat conditions like Alzheimer's disease and glaucoma. Anticholinergic drugs have opposite effects and are used to treat cholinergic intoxication.

1. AUTONOMIC NERVOUS SYSTEM AND
AUTONOMIC DRUGS
• I. Parasympathetic nervous
system drugs:

2. • 1. The human’s body is made up of systems
including nervous system.

3. • The Nervous system is made up of central
nervous system (CNS) and peripheral nervous
system.

4. • The peripheral nervous system is made up of two
divisions:
A. Efferent division ( include neurons that leave the
CNS and transmit impulses from the CNS to the
peripheral parts of the body)
B. Afferent division (Include neurons that bring
impulses from the peripheral parts of the body to
the CNS)

5. • The Efferent division of the peripheral
nervous system is also divided into:
a) Autonomic nervous system
b) Somatic nervous system

6. • The autonomic nervous system is
subdivided into:
I. Parasympathetic nervous system (PNS)
II. Sympathetic nervous system (SNS)
III. Enteric nervous system (ENS)

8. • Parasympathetic nervous system:
• It is a pathway of impulses from the CNS to
the peripheral parts of the body.
• This path consists of two neurons meet each
other in a node called GANGLIA

9. • The neuron/fibres which is before the ganglia from
the CNS side is called PRE-GANGLIONIC Neuron
• The fiber which is in front of ganglia from the organ
side is called POST-GANGLIONIC Neuron.
• the preganglionic fibers are long while the post-
ganglionic fibers are short

10. • The parasympathetic preganglionic fibers
arise from the cranial nerves (III, VII, IX and
X) of brain stem and from 2nd
, 3rd
and 4th
sacral
segments of the spinal cord
• The preganglionic fibers run almost to the
organ which is innervated and synapse with
postganglionic fibers in ganglia near or on
the effector organ.

11. Figure: shows areas on spinal cord from where parasympathetic
preganglionic fibers (blue colored lines) arise.

12. Organs which are innervated by
parasympathetic nervous system:
• The cranial nerves III, VII and IX affect :
• Pupil
• Salivary gland secretion

13. The vagous nerve X carries fibers to:
• Heart
• Lungs
• Stomach
• Upper intestine
• ureter

14. • The sacral fibers innervate:
• The distal colon
• Rectum
• Bladder and
• reproductive organs.

15. Function of parasympathetic nervous
system
• In physiological terms, the parasympathetic nervous
system is concerned with conservation and
restoration of energy.
• It causes:
• Reduction in heart rate
• Reduction in blood pressure
• Facilitates digestion and absorption
• Facilitates the excretion of waste products.
• Usually acts to oppose or balance the actions of
sympathetic system and dominates over it in “rest
and digest” situations

16. • Neurotransmitter:
• The chemical transmitter at both pre and
post-ganglionic synapses in the
parasympathetic nervous system is
Acetylcholine (Ach).

17. • The drugs acting on these receptors are:
A. Cholinergic agents
B. Anticholinergic agents

18. A. Cholinergic agents
• These are the agents that bind to the Ach receptors or
which inhibit the acetylcholineesterase (AChE) and make
Ach available for binding with its receptors.
• Classification of cholinergic agents:
I. Direct acting cholinergic agents:
i. Choline esters:
Acetylcholine
Methacholine

19. Carbachol
Bethanchol
i. Naturally occuring alkaloids:
Pilocarpine
Muscarine
Nicotine
Lobeline
Arecholine

20. I. Indirectly acting cholinergics:
i. Reversible:
Physostigmine (tertiary amine)
Neostigmine (quaternary)
Pyridostigmine (-do-)
Edrophonium (-do-)

21. i. Irreversible:
a. Alkyl-phosphate group:
TEPP (Tetra-ethyl-pyro-phosphate)
HETP (Hexa-ethyl-tetra-phosphate)
DFP (DI-isopropyl-fluro-phosphate)
OMPA (Octa-methyl-pyrophosphate)
b. Aryl group:
Chlorothion
Malathion
Parathion
Diazinon

22. • Miscellaneous :
Tacrine
Rivastigmine
Galantamine
Donepezil

23. ACETYLCHOLINE
Ach is a cholinergic agent and considered as a
prototype of this group.
• Synthesis of Ach:
• Its synthesis starts by pumping of choline from extra
cellular space to intra cellular space at nerve ending
where the choline will combine with acetyl-coA in
the presence of choline-acetyltransferase to form
Ach.

25. • Storage of Ach:
• After synthesis of Ach, it is stored in a synaptic
vesicles at the nerve ending as shown in the
diagram

26. • Release of Ach:
• On arrival of nerve impulse, the vesicles come
close to nerve ending’s membrane and make
pores/channels for the release of Ach.

27. • Binding of Ach:
• After Ach released from the synaptic vesicles, it
diffuses across the synaptic space where it will bind
with specific receptors on the postsynaptic
neuron/organ as well as presynaptic neuron.
• There are two types of receptors for Ach
a) Muscarinic receptors (M1,M2, M3, M4, M5)
b)Nicotinic receptors (Nn, Nm)

28. • Fate of Ach:
• Ach is very rapidly hydrolyzed in the synaptic cleft by
acetylcholinesterase (AChE) to choline and acetate.
• The choline is transported back to the presynaptic
nerve ending by a Na+ coupled transportor where it
will be acetylated to form another Ach and stored till
next impulse occur.

30. • Pharmacological actions:
• Muscarinic actions:
• Eye(M3):
• Causes constriction of the smooth muscle of
iris sphinctor/pupil leading to myosis

31. • Causes contraction of the ciliary’s muscle
leading to accommodation for near vision.

32. • The iris will be pulled away from the angle of
the anterior chamber as a result the
trabecular meshwork will be opened leading
to drainage of fluid and dec I.O.P.

33. • CVS
Heart(M2) :SA node rate dec
Atrial contractility dec
AV node rate dec
Ventricular contractility slightly dec
Blood vessels (M3):
only skin of face and neck is innervated
it cause dilation of vessels causing flushing

34. • Respiratory system (M3):
• Ach stimulates M3 receptors leading to constriction
of bronchial muscles and increase bronchial
secretions leading to asthma
• GIT (M3):
• It will increase the motility of GIT wall and relaxes
the sphincter and causes defecation and diarrhea

35. • Genitourinary tract (M3):
• It will cause contraction of the urinary bladder and relaxation
of its sphincter leading to maturation
• uterus of pregnant will be contracted
• Secretory glands and temperature (M):
• Lacrimal, nasopharyngeal, salivary, sweat glands secretions as
well as gastric secretions will be increased
skin temperature will increase.
• CNS:
• both M1 and M3 are available in CNS and present variety of
response for cholinergic agents

36. • Nicotinic actions:
• they will cause stimulation and contraction of
skeletal muscles causing inc in strength of
muscle and in high doses they cause paralysis
of the muscle
• It will stimulate and activate all the ganglias
including adrenal medulla.
• It will stimulate central nervous system
leading in high doses to exitation

37. • Clinical uses:
Clinically Ach is not used due to its rapid metabolism by
acetylcholinesterase at the synaptic cleft
But its availability at the synaptic cleft can be increased
by indirect acting agents that bind the
acetylcholineesterase and thus prevent the
degradation of the acetylcholine and make it
available for action.

38. • Alzheimer’s disease:
Tacrine
Rivastigmine
Galantamine
Donepezil
• glaucoma:
Pilocarpine
Carbachol
Physostigmine
Echothiophate

39. • For GIT disorders like Postoperative ileus:
• For Urinary disorders like urinary retention that may occur
postoperatively or postpartum
Bethanechol
• Myasthenia gravis:
Edromethonium (diagnosis)
Neostigmine
Pyridostigmine
d-tubocurarine (diagnosis)

40. • Anticholinergic intoxication:
Physostigmine
(only in dangerous situation of elevated temperature and
cardiac arrhythmias)
• Smoking cessation:
Varenicline
• Dryness of mouth associated with sjogren’s syndrome:
Pilocarpine (has been used)
Cevimeline (newly developed drug)

41. • Adverse effects:
• CNS: excitation
• Eye: myosis and lacrimation
• Mouth: excessive salivation
• Bronchi: excessive secretions and bronchial contraction leading to Asthma
• Heart: bradycardia
• GIT: increase acidic secretions and may cause peptic ulcer, Increase GIT
motility leading to cramps and diarrhea
• Skin: excessive sweating
• Urinary system: involuntary urination
• Skeletal muscle: excitation and in high dose cause muscle paralysis

42. • Contraindications:
• Asthmatic patient
• Peptic ulcer
• Bradycardia
• Obstructive urinary bladder

43. B. ANTICHOLINERGIC AGENTS