Stimulates many medullary centres.
Vagal, respiratory and vasomotor.
Anti-motion sickness property.
High dose cause
primarily in modifications of the heart rate:
very low dose, it can give a slight cardiac slowing
therapeutic dose there is generally cardiac acceleration
It does not have vascular effects since there is no
parasympathetic tonus on the vessels but it inhibits
vasodilatation caused by an intravenous injection of
It does not induce modifications of arterial pressure in spite
of increased cardiac rate.
in very high or toxic dose, it induces a fall of the arterial
pressure by depression of the vasomotor centers
Acid, pepsin and mucus in stomach.
Inhibition of sweating
Temperature regulatory centre in hypothalamus
Blocks the response of sphincter muscle of iris and ciliary
muscles to cholinergic stimulation thus causing mydriasis.
Stronger preparation also paralyzes accommodation.
Acts within 15-30 m and duration is 3-8 h.
typically used during eye examinations such as the dilated
fundus examination, but it may also be used before or after eye
It is a smooth muscle relaxant.
Irritable Bowel Syndrome (also known as spastic colon).
It relieves muscle spasms and cramping in the gastrointestinal
tract by blocking the activity of acetylcholine on cholinergic
(muscarinic) receptors on the surface of muscle cells.
N receptor antagonist, acts in autonomic ganglia.
Does not have any effect on muscarinic Ach receptors.
Acts at receptors at neuromuscular junction responsible for
skeletal muscle motor response.
The main reasons for using anticholinergic drugs were
drying of secretions and protection against vagal over
Blocks responses to vegal refluxes induced by sergical
manipulations of visceral organs.
Nervous and drug induced diarrhoea.
Tripathi KD. Anticholinergic drugs.In Essentials of medical
Pharmacology. 5th ed. JP Brothers Medical publishers (P) Ltd:
New Delhi; 2003. pp. 93-102.
Katzung, Bertram.G, Basic and clinical pharmacology.10th ed.
Mc Graw Hill. USA(NY); 2006. pp. 482-9.
Goodman & Gilman’s, The Pharmacological Basis Of
Therapeutics. 11th ed. Mc Graw Hill. USA(NY); 2006. pp. 121-