PHRM 825: Anticholinergics Flashcards
Anticholinergics bind to the receptor and disrupt binding of what molecule?
Acetylcholine
What are muscarinic receptors?
Acetylcholine regulated G protein-coupled receptors
What are anticholinergics also known as?
Antimuscarinic
How do anticholinergics cause mydyriasis?
They inhibit ACh action on M3 receptor in pupillary constrictor muscle
How do anticholinergics cause cycloplegia
Inhibit ACh action on M3 receptors in ciliary muscle
What is cycloplegia?
Loss of focus/regulation of lens thickness in the eye
How do anticholinergics cause incontinence?
Bladder relaxation via M3 receptor which mediates contraction of the bladder and M2 receptor (indirectly) inhibits relaxation
How do anticholinergics help with irritable bowel syndrome?
Induce GI tract intestinal paralysis (antispasmodic agents); reduce secretions (was considered useful for ulcers)
How/why are anticholinergics used as a pre-operative anti-secretory?
Used with inhalant anesthetics to reduce accumulations of secretions (salivary, mucous membranes of respiratory tract)
How are anticholinergics used to treat COPD?
Reduce secretions, cause bronchial dilation (used in combination with a beta-adrenergic agonist)
What are possible clinical uses of anticholinergics?
- Ocular exams
- Incontinence
- IBS
- Pre-operative anti-secretory
- COPD
- Motion sickness
- Parkinson’s disease
What is the mechanism of antimuscarinics?
Competitive and reversible inhibition of muscarinic receptor activation by preventing the binding of acetylcholine
What are the 2 categories that most antimuscarinics fall into?
Tertiary amines and quaternary amines
What are tertiary amines mainly used for?
Ocular and CNS applications
What are quaternary amines mainly used for?
GI tract and peripheral applications
What are 2 long acting tertiary amines?
Atropine and scopolamine
What are 3 short acting tertiary amines?
Homatropine, cyclopentolate, and tropicamide
What tertiary amine is sued for Parkinson’s?
Benztropine (Cogentin)
What quaternary amines are used for GI disorders?
Glycopyrrolate and propantheline bromide (probanthine)
What quaternary amine is used to treat COPD
Ipratropium bromide
What is the mnemonic device that summarizes the symptoms for atropine overdose?
Red as a beet, dry and a bone, blind as a bat, hot as a firestone, and mad as a hatter
What are clinical uses for nicotinic receptor antagonists?
- Muscle relaxation during surgery
- Tracheal intubation
- Control of ventilation (patients with ventilatory failure)
- Treatment of convulsions
What are the 2 modes of action for neuromuscular blockers on the nicotinic receptor?
Depolarizing competitive and nondepolarizing competitive
Which neuromuscular blockers have an extremely short duration of action?
Depolarizing neuromuscular blocker
Which neuromuscular blocker has a very short duration of action?
Succinylcholine
Which neuromuscular blocker has a very long duration of action?
Pancuronium
