Chp 20 Cholinergic Drugs Flashcards
(40 cards)
Cholinergic drugs
(cholinergic agonists, parasympathomimetics) the class of drugs that stimulate the parasympathetic nervous system
Acetylcholine
the neurotransmitter responsible for transmission of nerve impulses to effector cells in the parasympathetic nervous system
What are the two types of cholinergic receptors and what are they determined by?
Nicotinic receptors & Muscarinic receptors
Determined by location and action once stimulated
Where are nicotinic receptors located?
in the ganglia of both the PSNS and SNS
Why are nocotinic receptors named that?
because they can be stimulated by the alkaloid nicotine
Where are muscarinic receptors located?
postsynaptically in the effector organs of the PSNS (smooth muscle, cardiac muscle, glands)
Why are muscarinic receptors named that?
because they can be stimulated by the alkaloid muscarine
How do direct acting cholinergic drugs work?
they bind to cholinergic receptors and activate them
How do indirect acting cholinergic drugs work?
they inhibit the enzyme acetylcholinesterase, which breaks down ACh. This results in more ACh available at the receptors.
Parasympathetic Nervous System is called what?
the “rest and digest” system
What are the effects of cholinergic drugs on the intestine and bladder?
increased gastric secretions
increased gastrointestinal motility
Increased urinary frequency
What are the effects of cholinergic drugs on the eyes?
Constriction of pupils (miosis)
Reduced intraocular pressure
What are the effects of cholinergic drugs on the cardiovascular system?
Decreased heart rate
Vasodilation
What are the effects of cholinergic drugs on the respiratory system?
bronchial constriction
narrowed airways
Which receptors do recommended doses of cholinergics primarily effect?
mascarinic receptors which produced desired effects
Which receptors are stimulated from high doses of cholinergics?
nicotinic receptors which can cause many undesired effects.
cholinergic crisis
Sever muscle weakness and respiratory paralysis due to excessive acetylcholine; often seen in patients with myasthenia gravis as an adverse effect of drugs used to treat the disorder.
myasthenia gravis
A weakness and rapid fatigue of muscles under voluntary control.
What are the symptoms of cholinergic crisis?
circulatory collapse, hypotension, bloody diarrhea, shock, and cardiac arrest
What are the early signs of cholinergic crisis?
abdominal cramps, salivation, flushing of the skin, nausea, and vomiting
What are direct acting cholinergics used to treat?
intraocular pressure in patients with glaucoma
What are some example of direct acting drugs for glaucoma and intraocular surgery and why are they limited to mostly topical?
echothiophate
carbachol
pilocarpine
They are poorly absorbed orally
What is the direct acting cholinergic bethanechol used for and how is it administered?
- increases tone and motility of bladder and GI tract
- relaxes sphincters in bladder and GI tract, allowing them to empty
- helpful for postsurgical atony of the bladder and GI tract
- *Administered orally or by subcutaneous injection
What are indirect-acting cholinergics used for?
- diagnoses and treatment of myasthenia gravis
- to reverse neuromuscular blocking drugs
- to reverse anticholinergic poisoning (antidote)
