Anticholinergics Flashcards
Ocular effects of atropine
Mydriasis - relaxes the iris sphincter, allows sympathetic tone to predominate on the radial muscle
Blocks accommodation - relaxes the ciliary muscle, increasing tension on the ligaments, thereby flattening the lens
Inhibits lacrimation
ATROPINE
Antagonist at all mAChRs
Reverse muscarine or AChE inhibitor poisoning,
Long lasting pupil dilation
Anti diarrheal
Cardiac effects of atropine
Standard dose - increase HR and AV conduction by blocking cabal input
Very low dose - initial decrease of HR by blocking presynaptic receptors
Respiratory effects of atropine
Bronchial smooth muscle relaxation and dilation
Inhibits secretion
GI and urinary effects of atropine
Relaxes GI tone (not sphincters), prolong intestinal transit time
Inhibits gastric acid secretion
Relaxes detrusor muscle –> urinary retention
CNS effects of atropine
Tertiary amine! Can be distributed to CNS
Sedation, confusion, hallucinations
Scopolamine more sedating than atropine
Atropine first causes stim then sedating effect
Effect of atropine on vasculature
No significant effect!
No sig para input to vasculature, so no sig effect on vasc or BP
SCOPOLAMINE
Atropine-like
Motion sickness
TROPICAMIDE
Cyclopentolate
Homatropine
Antagonist a all mAChRs
Short acting, fast
Pupil dilation (mydriatic)
IPRATROPIUM Tiotropium (longer acting)
Antagonist at mAChRs
Quat amine: local action
Used for COPD as a bronchodilator
TOLTERIDINE
Antagonist at bladder mAChRs
Used for over active bladder
DICYCLOMINE
Antagonist at GI mAChRs
Used for IBS
Relaxes intestinal smooth muscle
GLYCOPYRROLATE
Antagonist at mAChRs
Uses:
Preop inhibition of secretions
Prevention of excessive generalized sweating
Prevention of muscarinic side effects in pts receiving NEOSTIGMINE to reverse neuromuscular block
Benztropine
Lipid soluble mAChR antagonist
Used to relieve extrapyramidal symptoms in Parkinson’s pts
Antimuscarinics block…
SLUD
Salivation
Lacrimation
Urination
Defecation
Adverse effects of antimuscarinics
Dry as a bone, red as a beet, hot as a bare, blind as a bat, mad as a hatter
Dry mouth (xerostomia)
Blurred vision (mydriasis and cycloplegia)
Hot, flushed skin (anhidrosis and cutaneous vasodilitation)
Constipation
Difficulty urination
Tachycardia
CNS Effects: confusion, sedation, delirium
Classes of other drugs of which some members have anti-muscarinic activity
Antihistamines
Antidepressants
Phenothiazine antipsychotics
Pharmacological effects of nicotine
Stimulation of autonomic ganglia followed by ganglionic blockade
Stimulation of adrenal medulla (secretion of epi)
Stimulation of CNS: alerting response; change in resp
HEXAMETHONIUM
Antagonist at nAChR at ganglion
Prevents baroreceptor reflex
MECAMYLAMINE
Antagonist at nAChR at ganglion
Improve GI absorption
Tourette’s syndrome
