Pharmacology

1. PARASYMPATHOMIMETICS/
CHOLINOMIMETICS/
CHOLINERGIC AGONISTS
DR.FOUZIA

4. CLASSIFICATION OF CHOLINERGIC DRUGS
1-Directly acting:
Acetyl choline ester
Methacholine
Bethanechol
Pilocarpine
2-Indirectly acting:
Inhibiting acetylcholinesterase (Reversible)
Neostigmine
Pyridostigmine
Physostigmine

5. CLASSIFICATION OF CHOLINERGIC DRUGS
2-Indirectly acting:
Inhibiting acetylcholinesterase (Irreversible)
Malathion
Parathion
Tabun
Sarin

6. ACETYLCHOLINE
Acetyl choline is the primary neurotransmitter.
It produces its effects by acting on
Muscarinic receptors:
M1: CNS
M2: Heart
M3: Most parts of body
Nicotinic receptors:
Nm: Neuromuscular junction
Nn: Autonomic ganglia

7. ACETYLCHOLINE
Pharmacological effects:
Eye:
Miosis
Accommodation
Increased drainage of aqueous humor
Increased lacrimation
CVS:
↓Heart rate (Bradycardia)
↓Force of contraction
Hypotension

8. ACETYLCHOLINE
Respiratory system:
Bronchoconstriction
↑ Bronchial secretions
GIT:
↑Secretions of all glands
↑Motility of gut
Relaxation of sphincters
Defecation
Genitourinary system:
Contraction of bladder and relaxation of sphincter
Voiding of urine

9. ACETYLCHOLINE
CNS:
Tremor
Hypothermia
Peripheral nervous system:
Stimulation of both sympathetic and parasympathetic ganglia
Neuromuscular junction:
Skeletal muscle contraction

10. INDIRECTLY- ACTING CHOLINERGIC AGONIST
/ANTICHOLINESTRASES

11. ANTICHOLINESTRASES
Reversible
Physostigmine
Neostigmine
Pyridostigmine
Edrophonium
Irreversible
Malathion
Parathion
Tabun
Sarin

12. IRREVERSIBLE ANTICHOLINESTRASES
1-Organophosphate compounds.
2-Form an irreversible complexes with the enzyme.
3-Highly lipid soluble, rapidly absorbed from intact skin, mucosal surfaces and
GIT and cross BBB.
Organophosphate poisoning:
Occupational –
While spraying insecticides
Accidental –
Consumption of agricultural products sprayed with insecticides.
Suicidal –
Ingested intentionally

14. TREATMENT OF ORGANOPHOSPHATE POISONING
1-Termination of further exposure to the poison
Wash the skin and mucous membranes with soap and water
Gastric lavage according to need.
2-Supportive Measures
A-Maintenance of patent airway, oxygen supply, and artificial
respiration.
B- Maintain BP, hydration
C- Control of convulsions with diazepam.

15. TREATMENT OF ORGANOPHOSPHATE POISONING
3. Specific antidotes
I-Atropine :
Acts as competitive antagonist and reverses effects of excess acetylcholine
2 mg I/V repeated every 10 min till dryness of mouth or miosis disappears
2-Cholinesterase re-activator :
Bind with cholinesterase and leads to its activation which then metabolizes
acetylcholine
Pralidoxime, Obidoxime
I/V slowly in a dose of 1–2 g

16. CLINICAL USES OF PARASYMPATHOMIMETICS
1-Acute angle-closure glaucoma
2-Post-operative ileus
3-Congenital Megacolon
4-Neurogenic bladder
5-Post-op urinary retention
6-Myesthenia gravis
7- Paroxysmal supraventricular arrhythmia
8-For intoxication of atropine
9-Alzheimer’s disease
10- Sjogren’s syndrome