CHOLINERGIC AGONISTS & ANTAGONISTS 2 Flashcards
What is ATROPINE and whats its function?
Cardiovascular system
Secretions
• Reversible competitive antagonist at muscarinic receptors. that Prevents acetylcholine from binding
ACTIONS: • Eye: Mydriasis. Cycloplegia. • GI: Reduces gastric motility. • Urinary system: Decreases hypermotility of urinary bladder.
Cardiovascular system: Low doses: bradycardia. Due to blockade of
presynaptic M2 receptors. Moderate to high therapeutic doses: Blockade of atrial M2 receptors: tachycardia.• High doses cause cutaneous vasodilation.
Secretions: Inhibition of sweat glands may cause high body
temperature.
• Antispasmodic: to relax GI tract and bladder.
What are the adverse effects of ATROPINE?
- Dry mouth, blurred vision, sandy eyes, tachycardia, constipation urinary retention.
- Effects on CNS: restlessness, confusion, hallucinations, delirium, which may progress to depression, collapse of the circulatory and respiratory systems and death.
SCOPOLAMINE uses?
- Prevention of motion sickness.
- To block short-term memory: sometimes used in anaesthetic procedures.
Binds to M1 receptors in the vomiting center in the brain and prevels the normal fuction
IPRATROPIUM AND TIOTROPIUM uses and effects?
QUATERNARY AMMONIUM MUSCARINIC ANTAGONISTS
• Used as inhalational drugs in the treatment of
chronic obstructive pulmonary disease (COPD).
• Also used as inhalational drugs in asthma.
HOMATROPINE TROPICAMIDE uses?
TERTIARY AMINE MUSCARINIC ANTAGONISTS
- Used as mydriatic for fundoscopy.
- Produce mydriasis with cycloplegia.
- Preferred to atropine because of shorter duration of action.
BENZTROPINE TRIHEXYPHENIDYL
TERTIARY AMINE MUSCARINIC ANTAGONISTS
• Used to treat Parkinson’s disease and the extrapyramidal effects of antipsychotic drugs.
GLYCOPYRROLATE
ANTIMUSCARINIC AGENTS
- Used orally to inhibit GI motility.
- Used parenterally to prevent bradycardia during surgical procedures.
TOLTERODINE
ANTIMUSCARINIC AGENTS
Used for overactive bladder.
What are some CONTRAINDICATIONS OF ANTIMUSCARINIC AGENTS
- Contraindicated in patients with angle-closure glaucoma.
- Should be used with caution in patients with prostatic hypertrophy and in the elderly.
What are the main functions of GANGLION BLOCKERS?
- By prolonged depolarization: Nicotine.
- By antagonism of nicotinic receptors: Hexamethonium and mecamylamine.
- The effect of the ganglion blocker is to remove the dominant control
What is the NONDEPOLARIZING BLOCKERS NEUROMUSCULAR BLOCKERS and its function?
TUBOCURARINE
• Prototype of the nondepolarizing drugs.
MECHANISM OF ACTION • Competitive antagonists.
USES • Adjuvant drugs in anaesthesia during surgery to
relax skeletal muscle.
What is the DEPOLARIZING BLOCKERS NEUROMUSCULAR BLOCKERS and its function?
SUCCINYLCHOLINE
• Binds to the nicotinic receptor and depolarizes the junction. Persists in the synaptic cleft, stimulating the receptor: receptor desensitizes. This leads to flaccid paralysis.
USES • Rapid endotracheal intubation. • ECT.
• Malignant hyperthermia: Due to excessive release of Ca2+ from the SR. • Most incidents due to combination of succinylcholine and an halogenated anesthetic.
• Treatment: dantrolene. Blocks release of Ca2+
from SR.
HEMICHOLINIUM-3
INHIBITORS OF ACETYLCHOLINE SYNTHESIS
- Blocks the CHT.
- Prevents uptake of choline required for ACh synthesis.
- Research tool.
VESAMICOL
INHIBITORS OF ACETYLCHOLINE STORAGE
- Vesamicol blocks the ACh-H+ antiporter that is used to transport ACh into vesicles, thereby preventing the storage of ACh.
- Research tool.
BOTULINUM TOXIN
INHIBITORS OF ACETYLCHOLINE RELEASE
- Inhibits acetylcholine release.
- Injected locally into muscles for treatment of several diseases involving muscle spasms.
- Also approved for cosmetic treatment of facial wrinkles
