Pharm: Acetylcholinesterase inhibitors Flashcards
What’s one of the main distinctions between direct-acting muscarinic agonists and indirect acting cholinesterase inhibitors?
The cholinesterase inhibitors stimulate the nicotinic acetylcholine receptors too.
What long-term drug is used to treat myasthenia gravis?
Pyridostigmine (think of the community lady cleaning up the Gravis grafitti with “Community PRIDE” on her jacket)
What is the clinical role of edrophonium?
Because it is short-acting, it is not useful for treating MG. However, some patients with MG might present with worsening weakness that could be due to insufficient acetylcholine (undertreated) or too much acetylecholine (called cholinergic crisis- results from refractory NMJ receptors from overtreatment).
Giving edrophonium can differentiate the two. If edrophonium helps, then the patient is undertreated.
Explain how succinylcholine is a depolarizing agent.
It mimics acetylcholine and depolarizes the membrane, but it does not get degraded as easily- preventing further action potentials.
Explain how physostigmine can correct atropine overdose.
Atropine blocks muscarinic receptors, leading to parasympatholytic symptoms- “mad as a hatter, blind as a bat, hot as a hare”. (Think of the Alice in Wonderland graffiti)
Physostigmine can generate more acetylcholine, thus outcompeting atropine for muscarinic sites.
What is the DUMBBELS mnemonic for parasympathetic symptoms (aka acetylcholinesterase inhibitor toxicity and organophosphate poisoning)?
All things that come from muscarinic activation: Diarrhea Urination Miosis Bradycardia Bronchospasm Lacrimation Salivation
What drugs can correct organophosphate poisoning?
- Pralidoxime- by regenerating acetylcholinesterases by hydrolyzing the covalent bond binding the organophosphate to the cholinesterase (“Put a LID on the tOXic pesticide”) for the peripheral side effects and paralysis- can’t cross BBB
- Atropine- muscarinic antagonist for the CNS side effects (but can’t do anything for paralysis because it can’t bind to nicotinic receptors)
Pralidoxime binds to organophosphate-bound acetylcholinesterase, which helps treat organophosphate poisoning, but it only works __________.
quickly after poisoning (think of the old man spraying poison on the dumpster)
What three acetylcholinesterase inhibitors can treat Alzheimer’s?
Galantamine (think of the GALA of old people for Alzheimer’s awareness)
Rivastigmine (“ReVerse the STIGMa!”)
Donepazil (old people that are DONe with the Puzzle)
What is the suffix of acetylcholinesterase inhibitors?
“-stigmine” (think of the word STIGMA that was on the vandalized, turned over garbage bin)
What is the difference between tertiary and quaternary acetylcholinesterase inhibitors?
Quaternary aceytlcholinesterase inhibitors (edrophonium, pyridostigmine, neostigmine- PEN) are synthetic and do NOT cross the BBB (think of the QUARTers only PHONe booth).
Tertiary acetylcholinesterase inhibitors (physostigmine) are naturally occurring.
What is myasthenia gravis?
MG is a autoimmune disease where antibodies attack nicotinic ACh receptors at motor endplates aka skeletal muscle NMJ (think of the electrical outlet on the striated muscle wall with graffiti of a GRAVe around it)
What are the classic symptoms of skeletal muscle weakness that is seen in myasthenia gravis?
progressive proximal weakness, ptosis, diplopia, difficulty swallowing that gets worse with use
The edrophonium diagnostic test is also called the ___________.
tensilon test (think of the tense phone cord)
What are nondepolarizing agents that are used for muscle paralysis?
Rocuronium, vecuronium, pancurionium- “curares” that block endplate preventing transmission (think of CURARE crayons stuck in the end plate outlet)
