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Old 10-26-2011
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Default myasthenia gravis

a colleague with myasthenia gravis wants to assist him to E/R because he is experiencing muscle weakness and found it difficult to titrate his drug dosage because he has had flu.
you note that he has a slight temperature,shallow repiration and gray-blue skin pallor.what would be most appropriate drug to be given at this time/

1)albuterol
2)atropine
3)neostigmine
4)physostigmine
5)edrophonium
6)propanolol
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Old 10-26-2011
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Dont you start with neostigmine? Whats your answer?
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He has muscle weakness. Muscle weakness causes pulmonary insufficiency. Pulmonary insufficiency is causing his other symptoms. Therefore, we must treat him with a fast-acting ACh inhibitor, such as neostigmine or physostigmine.

Am I correct?
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You are correct. In that case we should use physostigmine which has faster onset than neostigmine. Physostigmine onset within 1 to 2 minutes whereas neostigmine shows effect in 20 mins ----by the time neostigmine starts working px maybe already in a coma... .... Therefore I change my vote to (4)physostigmine

Last edited by HaipengWang; 10-26-2011 at 09:03 PM.
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Old 10-26-2011
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By the way, jjsanchezramirez sweetie, neostigmine or physostigmine are not "ACh inhibitor". On the contrary, they are choleliesterase inhibitor. Sorry being fussy, it might just be a typo of yours. no biggie...
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Quote:
Originally Posted by HaipengWang View Post
By the way, jjsanchezramirez sweetie, neostigmine or physostigmine are not "ACh inhibitor". On the contrary, they are choleliesterase inhibitor. Sorry being fussy, it might just be a typo of yours. no biggie...
Absolutely right. I'm an IMG and I confused the abbreviations. Sorry! :P
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Correct Answer correct answer

5)EDROPHONIUM

edrophonium is short acting ACE reversible inhibitor used in Dx of myasthenia gravis.
also used in D/D of myasthenia gravis and cholinergic crisis ....

if s/s reduce after edrophonium then its MG and give neostigmine(dont give physostigmine as it will enter brain and cause cns side effects)

if s/s worsen then its cholinergic crisis and REDUCE DOSE OF NEOSTIGMINE..
hope its clear now..
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Ohh thanks. That makes sense
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Thanks for clearing that out.
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Old 06-21-2012
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Default Question

Question..
Edrophonium is used to diagnose MG, but the question clearly says the collegue has myesthenia gravis. So we know he already has it right? Shouldn't we now treat the symptoms? Please clarify!!
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Old 06-21-2012
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Quote:
Originally Posted by alphadoc View Post
Question..
Edrophonium is used to diagnose MG, but the question clearly says the collegue has myesthenia gravis. So we know he already has it right? Shouldn't we now treat the symptoms? Please clarify!!
Edrophonium is given to differentiate b/w cholinergic and Myasthenic crisis.. Both present with similar symptoms but one is due to excess Ach and other depleted ACH respectively..

Edrophonium>>improves>>Myasthenic crisis Rx : increae dose of neostigmine

Edrophonium>>worsens s/s>>cholinergic crisis Rx: cut down neostigmine dose
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Old 06-22-2012
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Quote:
Originally Posted by alphadoc View Post
Question..
Edrophonium is used to diagnose MG, but the question clearly says the collegue has myesthenia gravis. So we know he already has it right? Shouldn't we now treat the symptoms? Please clarify!!
the patient has been diagnosed with MG, so he's probably being treated with Neostigmine. the symptoms described in the question could be due to MG itself or an overdose of the treatment ( Neostigmine)
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Old 06-22-2012
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Thank you to everyone who responded back, but I'm still slightly confused. If you don't mind, could you elaborate on exactly how edrophonium and neostigmine work i.e. its mechanism of action?

Also, just want to make sure.. it doesn't matter whether or not the patient has MG previously diagnosed, when the patient comes in with symptoms similar to MG, we give edrophonium to rule out cholinergic symptoms from some other cause to diagnose myesthenia crisis?
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Old 06-22-2012
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They're both AchE inhibitors, except that edrophonium acts fast and also loses its effect fast.

And yes, always give them a shot of edrophonium, unless maybe the patient tells you he just swallowed his whole prescription of neostigmine an hour back
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