Cholinergic Agonists and Antagonists Flashcards
drugs that stimulate the PNS are called ___
cholinergic agonists or parasympathomimetics (mimic the neurotransmitter acetylcholine)
____ is the neurotransmitter located at the ganglions and the parasympathetic terminal nerve endings
acetylcholine (ACh)
the two types of cholinergic receptors
muscarinic (stimulate smooth muscles and slow HR)
nicotinic (neuromuscular which affect the skeletal muscles)
two types of cholinergic agonists
direct-acting (act on receptors)
indirect-acting (inhibit action of enzyme acetylcholinesterase (AChE))
AChE does what
destroys acetylcholine
major responses of cholinergic agonists
stimulate bladder and GI tone, miosis (constrict pupil), and increase neuromuscular transmission
decreased HR and BP, increased salivary, GI, and bronchial secretions
are primarily selective to the muscarinic receptors but are nonspecific because the muscarinic receptors are located in the smooth muscle of the GI and genitourinary tracts, glands, and heart
direct-acting cholinergic agonists
monitor LFTs
a direct-acting cholinergic agonist that is used to increase urination in the treatment of urinary retention and neurogenic bladder
bethanechol chloride
a direct-acting cholinergic agonist that is used to treat gastroparesis, nausea, and GERD
metoclopramide
what is the direct-acting cholinergic agonist given in glaucoma that causes miosis
pilocarpine
what is the antidote to cholinergics?
IV atropine (anticholinergic)
do not act on the receptors, instead, they inhibit or inactivate the enzyme cholinesterase, permitting acetylcholine to accumulate at the receptor site
indirect-acting cholinergic agonists
a ChE inhibitor drug binds with ChE allowing acetylcholine to activate the muscarinic and nicotinic cholinergic receptors. This action permits skeletal muscle stimulation, which increases the force of muscular contraction. Because of this action, ChE inhibitors are useful to increase muscle tone for patients with ______
myasthenia gravis
___ are used to produce pupillary constriction in the treatment of glaucoma and to increase muscle strength in patients with myasthenia gravis
reversible ChE inhibitors
-stigmine
drugs that inhibits the actions of acetylcholine by occupying the acetylcholine receptors
cholinergic antagonists (anticholinergics)
major body tissues and organs that are affected by anticholinergic drugs
heart, respiratory tract, GI tract, urinary bladder, eyes, and exocrine glands
what are the major responses to anticholinergics
decrease in GI motility, decrease in salivation, mydriasis (pupil dilation), increase HR
other effects: decreased bladder contraction, which can result in urinary retention, and decreased rigidity and tremors related to neuromuscular excitement
what are the therapeutic uses of atropine (anticholinergic)
preop med to reduce salivation, increase HR for bradycardia, neuromuscular blockade reversal, cholinergic crisis, and mydriasis and cycloplegia for ocular exams
side effects of atropine (or like drugs)
xerostomia (dry mouth), nasal dryness, blurred vision, tachycardia, constipation, and urinary retention
nausea, HA, dehydration, seizures, hypotension or HTN, photophobia, and coma
**can’t pee, can’t see, can’t shit, can’t spit
anticholinergics affect the CNS by suppressing the tremors and muscular rigidity of parkinsonism, but they have little effect on mobility and muscle weakness
trihexyphenidyl, hydrochloride, biperiden, and benztropine
use caution because of sedative effect
