This document discusses the autonomic nervous system and pharmacology of adrenergic and cholinergic drugs. It describes the types and functions of adrenergic receptors and lists direct-acting, indirect-acting and mixed adrenergic agonists. It also discusses adrenergic receptor blockers and their uses for conditions like hypertension. The document outlines the actions of cholinergic receptors and lists cholinergic agonists and their clinical uses. It concludes by discussing anticholinergic agents and ganglionic blockers.

1. AUTONMOIC NEURVOUS
SYSTEM
DENTAL PHARMACOLOGY

6. ADRENERGIC AGONISTS
(SYMPATHOMIMETIC AGENTS)
• Adrenergic agonists mimic the
actions of sympathetic.
• Adrenergic neurons release
norepinephrine as the primary
neurotransmitter.
• NA from the synaptic cleft
diffuses into circulation and
gets inactivated by catechol-O-
methyltransferase (COMT) and
monoamine oxidase ( MAO)

8. Types, Distribution and Functions of
Adrenergic Receptors

10. 1. Direct-acting Sympathomimetics
Adrenergic Agonists Receptor Action Therapeutic Uses
1. Directly acting
Adrenaline a1-, a2-, B1-, B2- and Anaphylactic shock, Bronchial asthma
(acute), Cardiac arrest, to prolong the
Duration of local anaesthesia, to control
Epistaxis
(ABCDE)
• Noradrenaline a1-, a2- and B1-agonist Hypotensivestates
Isoprenaline B1- andB2-agonist Heart block, cardiac arrest
• Dobutamine Relatively selective Cardiogenic shock due to acute
B1-agonist myocardial infarction (MI), congestive
cardiac failure (CCF) or cardiac surgery
Salbutamol (Albuterol) SelectiveB2-agonists Bronchial asthma
Phenylephrine Selective a1-agonists Vasopressor agents, nasal decongestants,
as mydriatic (phenylephrine), allergic
rhinitis
• Naphazoline a1 + a2-agonists Nasal decongestants
(a1-stimulation),
• Clonidine, a-Methyldopa a2-agonists Hypertension

11. Adverse effects and contraindications
direct-acting
Adverse effects
– They are tachycardia, palpitation, headache,
restlessness, tremor and rise in BP.
– The serious side effects are cerebral haemorrhage
and cardiac arrhythmias.
contraindicated in most of the cardiovascular
diseases such as hypertension, angina, cardiac
arrhythmias, CCF, etc

12. 2. Indirect-acting Sympathomimetics
Adrenergic Agonists Receptor Action Therapeutic Uses
2. Indirectly acting
Amphetamine They act by releasing NA Narcolepsy, attention-deficit
hyperkinetic
Methamphetamine disorder (ADHD)
Methylphenidate
3. Mixed acting
Ephedrine a1, a2, B1 and B2 (direct
action)
Intravenous ephedrine is used
for the
+ releases NA (indirect
action)
treatment of hypotension due
to spinal
anaesthesia
Dopamine a1, a2, B1 and D1 +
releases NA
Cardiogenic shock, CCF with
oliguria

13. Adverse effects and contraindications
Indirect-acting
• The side effects are restlessness, insomnia,
confusion, fatigue, tremor, hallucinations and
suicidal tendencies.
• The cardiac side effects are tachycardia,
palpitation, hypertension, angina and cardiac
arrhythmias

14. ADRENERGIC RECEPTOR BLOCKERS
(SYMPATHOLYTIC AGENTS)
• Adrenergic-receptor antagonists block the
effects of sympathetic pathway.

15. ALPHA-ADRENERGIC BLOCKERS

16. Irreversible Nonselective a-Blocker
Phenoxybenzamine
• Peripheral vascular resistance is reduced due
to the blockade of vascular α1-receptors.
• Used in the treatment of pheochromocytoma.
• The side effects are hypotension, tachycardia,
palpitation, diarrhea, and impotence.

17. Reversible Nonselective a-Blocker
Phentolamine
• Has rapid onset but short duration of action. It
is used intra-operatively during surgery of
pheochromocytoma, in hypertensive
emergencies
• Adverse effects
– They include tachycardia, palpitation, arrhythmias;
angina and Myocardial Infraction may be
precipitated.

18. Selective α1-Blockers
Prazosin, Doxazosin, Tamsulosin, Terazosin
• Prazosin is a potent and selective a1-adrenergic
receptor blocker.
• Doxazosin is the longest-acting, selective a1-
blocker.
• Tamsulosin
– an uroselective a1-blocker (a1A). At low doses, it
reduces the resistance to flow of urine with little
effect on BP.
– It is the preferred a1-blocker for the treatment of
benign prostatic hyperplasia (BPH)

19. Selective α1-Blockers
• Therapeutic Uses
– Essential hypertension
– Benign prostatic hyperplasia
– Pheochromocytoma
• Adverse effects
– First-dose phenomenon: Within 30–90 min of oral
administration of prazosin, severe hypotension and
syncopal attacks may be seen with first dose.
• Therefore, the initial dose should be small . It is usually given
at bed time so that the patient remains in bed for several
hours and the risk of syncopal attack is reduced

20. BETA-ADRENERGIC BLOCKERS

21. BETA-ADRENERGIC BLOCKERS
Mechanism of action
– competitively block β-receptors.
Pharmacological actions
– Cardiovascular system:
• Decrease heart rate (negative chronotropic effect).
• Decrease the force of myocardial contractility (negative inotropic effect).
– Respiratory system:
• Blockade of B2-receptors in bronchial smooth muscle can produce severe
bronchospasm in patients with COPD and asthma.
• Selective B1-blockers such as atenolol, metoprolol, etc. are less likely to cause
bronchospasm.
– Skeletal muscle:
• On chronic use, B-blockers may cause skeletal muscle weakness and tiredness
due to blockade of B2-receptors of the skeletal muscle and blood vessels
supplying it. They also reduce stress-induced tremors.
– Metabolic effects:
• B-Blockers inhibit glycogenolysis and delay recovery from hypoglycaemia.
• They also mask the warning signs and symptoms of hypoglycaemia
– Eye: B-Blockers on topical administration decrease IOP

22. BETA-ADRENERGIC BLOCKERS
• Therapeutic uses
– Hypertension
– Angina pectoris and MI: B-Blockers reduce myocardial O2
demand
– Congestive cardiac failure , carvedilol, metoprolol and
bisoprolol
– Pheochromocytoma
– Glaucoma ,Timolol
– Prophylaxis of migraine: Propranolol, atenolol and
metoprolol
– Hyperthyroidism: The signs and symptoms of
hyperthyroidism such as tachycardia, palpitation, tremor,
anxiety, etc
– Acute anxiety states

23. BETA-ADRENERGIC BLOCKERS
• Adverse effects
– CNS: Sleep disturbances, fatigue and mental
depression.
– CVS: Bradycardia, heart block
– Muscular weakness and tiredness
– Withdrawal symptoms
– Mask the warning signs and symptoms of
hypoglycaemia

24. CHOLINERGIC AGENTS (CHOLINOMIMETICS,
PARASYMPATHOMIMETICS)
• Acetylcholine is rapidly
hydrolyzed by cholin-
esterases it has no
therapeutic application.
Cholinergic receptors
• Muscarinic: M1, M2, M3
Activated by muscarine, Ach.
• Nicotinic: NM (Skeletal muscle), NN
(neuronal ) Activated by nicotine,
Ach.

25. Muscarinic Receptor Stimulation
• Eye (M3) - miosis
• Heart (M2) - bradycardia and a decrease in
blood pressure
• Lungs (M3) – bronchospasm, increase
secretion
• Gastrointestinal - increase in motility (M3) , and
secretion (M1) .
• Glands (M3) - increase Secretion-sweat,
salivation, and lacrimation
• Blood vessels (M3) – vasodilatation

26. Cholinergic
agonists
Directly acting
(on the receptors)
Pilocarpine
Acetylcholine
Carbachol
Bethanechol
Indirectly acting
(anti-cholinesterase)
Reversible
Physostigmine
Edrophonium
Neostigmine
Irreversible
Organophosphorus
compounds
Parathion
Malathion
Sarin (nerve gases)

27. Clinical Uses
Directly acting
• Postoperative urinary retention, paralytic ileus
and dry mouth Bethanechol
• Glaucoma Carbachol, Pilocarpine
• Xerostomia Pilocarpine

28. Clinical Uses
Indirectly acting
Reversible Anticholinesterases
• Glaucoma Physostigmine
• Atropine poisoning Physostigmine
• Myasthenia gravis Neostigmine , Edrophonium
• Curare poisoning and reversal of non-depolarising
neuromuscular blockade Neostigmine
• Postoperative urinary retention and paralytic
ileus Neostigmine

29. Clinical Uses
Indirectly acting
• Irreversible Anti-cholinesterases
Organophosphorus compounds insecticides
Acute toxicity
• Excessive muscarinic and nicotinic stimulations
Muscarinic effects:
- Diarrhea
- Urination
- Miosis
- Bradycardia
- Bronchoconstriction
- Lacrimation
- Salivation
- Sweating
Nicotinic effects:
- Skeletal muscle excitation followed by
paralysis
- CNS stimulation :confusion, convulsions,
coma, and death occurs usually due to
respiratory failure.

30. Irreversible Anti-cholinesterases
Management of Organophosphorus compounds
toxicity :
• Muscarinic effects: atropine ( antimuscarinic)
• Regeneration of AChE: pralidoxime

31. ANTICHOLINERGIC AGENTS
(CHOLINERGIC RECEPTOR BLOCKERS)
SKELETAL MUSCLE RELAXENT

32. ANTIMUSCARINIC AGENTS
• These drugs block muscarinic-receptor-
mediated actions of acetylcholine on heart,
CNS, smooth muscles and exocrine glands.
• Leading to opposite action of
parasympathommetics.

33. Pharmacological Actions
• Central Nervous System
– Inhibit vomiting centre
– excitation , hallucinations, Sedation, coma (high dose)
• Exocrine Glands
– Decreased secretions (salivary, bronchiolar, sweat)
• Smooth Muscle
– Relax smooth muscles in gastrointestinal tracts and Delay gastric
emptying constipation
– Relax smooth muscles in the respiratory Bronchial dilation.
– Urinary retention
• Eye
– Mydriasis , decrease Lacrimation
• Cardiovascular
– Tachycardia

34. Clinical Uses
• Preoperative Medication : (Atropine )
– They inhibit salivary and bronchial secretions.
– To prevent bradycardia during anaesthesia.
• Sialorrhoea (hypersalivation):(glycopyrrolate,
propantheline)
– Used to decrease salivary secretion, e.g. during dental
procedures.
• COPD and bronchial asthma: (Ipratropium
,Tiotropium)
– They produce bronchodilatation

35. Clinical Uses
• Antispasmodics in intestinal, renal colic and
dysmenorrhoea. (hyoscine N- butyl bromide)
• Ophthalmologic Examinations (Tropicamide)
• Parkinsonism —Benzhexol
• Motion Sickness —Scopolamine (hyoscine).

36. ANTIMUSCARINIC
Adverse Effects
• Decreased secretions (salivary, bronchiolar,
sweat) ……. Dryness of the mouth
• Mydriasis
• Hyperthermia
• Tachycardia
• Sedation
• Urinary retention and constipation
• Behavioral: excitation and hallucinations

37. GANGLIONIC BLOCKERS
• Blockade of sympathetic
ganglia results in marked
hypotension.
• Blockade of parasympathetic
ganglia results in ‘atropine-like’
actions.
• Nicotine is obtained from
tobacco leaves. It has a
prolonged blocking effect on
the autonomic ganglia.

38. THE END