5. ATROPINE
1-Atropine is a tertiary amine belladonna alkaloid with a high affinity
for muscarinic receptors.
2-Atropine acts both centrally and peripherally.
Mechanism of action:
1-It binds competitively with muscarinic receptors prevents
acetylcholine from binding to those sites.
2-Its effects can be overcome by increasing the concentrations
of muscarinic agonists or by the use of anticholinesterase.
6. PHARMACOLOGICAL EFFECTS OF ATROPINE
1-Eye
Mydriasis (dilation of the pupil)
Loss of light reflex
Cycloplegia (Loss of accommodation)
Raised intranial pressure
Reduction of lacrimal secretions
2-GIT
Reduced motility of gut Constipation
Reduced secretions of stomach and small intestine.
7. PHARMACOLOGICAL EFFECTS OF ATROPINE
3-CVS
Increase in heart rate by blocking the M2 R on SA node.
4- Respiratory system
Bronchodilation
Reduced bronchial secretions
5- Genitourinary tract
Relaxation of smooth muscles of ureter and detrusor muscle of bladder
and contraction of sphincter Urinary retention
8. PHARMACOLOGICAL EFFECTS OF ATROPINE
6-Sweat glands
It suppresses thermoregulatory sweat gland so decreasing sweating and
increasing body temperature.
7-CNS
A-At toxic doses it produces excitement, agitation, hallucination, and
coma.
B-It reduces tremors of Parkinson’s disease.
C- It blocks cholinergic transmission in vestibular system.
9. THERAPEUTIC INDICATIONS OF ATROPINE
A-CNS disorders:
1- Parkinson’ disease
2- Motion sickness
B- Ophthalmic disorders
1-For measurement of refractive errors in children
2- To prevent synechia (adhesion) formation in uveitis and iritis.
C- Respiratory Disorders
Asthma
COPD
As part of preanesthetic medication to reduce secretions
11. THERAPEUTIC INDICATIONS OF ATROPINE
E- GIT
To reduce salivary secretion in heavy metal poisoning.
Antispasmodic: Intestinal colic, biliary colic
F- Urinary Disorders
Urinary urgency and incontinence of urine.
Nocturnal enuresis
12. THERAPEUTIC INDICATIONS OF ATROPINE
G- Cholinergic Poisoning
Organophosphate poisoning
H- Hyperhidrosis
I- General Anesthesia
To inhibit excessive salivation and secretion of respiratory tract
To prevent reflex vagal stimulation of the heart
14. ATROPINE
• Derived from atropa belladonna
• Longer duration of action.
• More CVS effects.
• CNS stimulant effect on
therapeutic doses.
• Less anti-emetic action.
• Causes excitement, agitation,
hallucination and coma at high
doses.
HYOSCINE
• Derived from hyoscyamus niger.
• Short duration of action.
• Less CVS effects.
• CNS depressant effect.
• More anti-emetic action, used in
motion sickness.
• Cause drowsiness, amnesia,
fatigue.
15. ADVERSE EFFECTS OF ATROPINE
ATROPINE TOXICITY
Dry mouth, Hyperpyrexia
Blurred vision, dry “sandy eyes”
Tachycardia
Urinary retention
Constipation
Effects on the CNS:
Restlessness, confusion, hallucinations, and delirium, which may
progress to depression, collapse of the circulatory and respiratory
systems, and death.
16. TREATMENT OF ATROPINE TOXICITY
Symptomatic treatment:
1-Treatment of hyperpyrexia – ice bag,
2-Artificial respiration, oxygen.
3-Removal of unabsorbed drug by gastric lavage with activated charcoal.
4-To counteract excitement and convulsions – diazepam.
Specific treatment –
Physostigmine slowly I/V
(1–4 mg in adults, 0.5–1 mg in children)
