About the ads

Go Back   Student Doctor Network Forums > Medical Student Forums > USMLE and COMLEX > Step I
Reload this Page Opioids - toxicity / withdrawal
Register FAQ SDN Live Mark Forums Read

Step I Discuss strategies and issues for the USMLE and COMLEX Step 1. RSS: Feed Icon


Reply
 
Thread Tools Display Modes
Old 07-19-2012, 03:26 AM   #1
2K Member
 
Phloston's Avatar
 
Join Date: Jan 2012
Location: Australia
Posts: 2,222
SDN Gold Donor
Default Opioids - toxicity / withdrawal

SDN Members don't see this ad. (About Ads)
With respect to the third row down (opioids) on p. 495 of FA2012, could someone please explain the exact mechanism as to why each one of those specific side-effects are seen for both toxicity and withdrawal?

It just seems like there's a mix of both muscarinic-like agonistic and antagonistic effects occurring with both toxicity and withdrawal, and I haven't quite put together the whys yet.

Thanks again,
Last edited by Phloston; 07-20-2012 at 08:13 PM.
Phloston is offline   Reply With Quote
Old 07-20-2012, 08:13 AM   #2
2K Member
 
Phloston's Avatar
 
Join Date: Jan 2012
Location: Australia
Posts: 2,222
SDN Gold Donor
Default
Anybody?
Phloston is offline   Reply With Quote
Old 07-20-2012, 08:36 PM   #3
1K Member
 
ijn's Avatar
 
Join Date: Nov 2009
Posts: 1,238
SDN 2+ Year Member
Default
According to Kaplan pharmacology it's too complex to be tested on for the MS2 level. There are a few fundamentals that I think are higher yield. Mu-opioid receptors stimulate G(i) complexes. High cAMP levels are associated with tolerance.

Miosis is specifically an antimuscarinic effect. Meperidine is an opioid noted for the lack of of antimuscarinic effects and has no miosis with intoxication.

The other side effects of opiates shouldn't necessarily classified as musarinic or antimuscarinic. They're mostly due to the central effects of mu-receptor interneurons. I don't know if we really have a solid grasp on the exact pathways other than seeing gross evidence of mu-stimulation. I'd be really suprised if the NBME tested on it. It's just something you have to memorize.
ijn is offline   Reply With Quote
Old 07-21-2012, 07:41 AM   #4
OMS III
 
An0MalY's Avatar
 
Join Date: Jan 2012
Posts: 48

Default
HAH i just so happen to have this article open: http://www.nejm.org/doi/full/10.1056/NEJMra1202561
__________________
"Procrastination leads to stagnation, and stagnation will always kill your ambition. And Ambition is the only thing keeping you working 16-hour days, seven days a week."

"I entered into the inner most part of myself.. I entered and saw with my souls eye, an unchangeable light shining above this eye of my soul and above my mind.. He who knows truth, knows that light, and he who knows that light, knows eternity."
An0MalY is offline   Reply With Quote
Old 07-21-2012, 02:05 PM   #5
Member
 
Join Date: Dec 2011
Posts: 28

Default
Quote:
Originally Posted by ijn View Post
According to Kaplan pharmacology it's too complex to be tested on for the MS2 level. There are a few fundamentals that I think are higher yield. Mu-opioid receptors stimulate G(i) complexes. High cAMP levels are associated with tolerance.

Miosis is specifically an antimuscarinic effect. Meperidine is an opioid noted for the lack of of antimuscarinic effects and has no miosis with intoxication.

The other side effects of opiates shouldn't necessarily classified as musarinic or antimuscarinic. They're mostly due to the central effects of mu-receptor interneurons. I don't know if we really have a solid grasp on the exact pathways other than seeing gross evidence of mu-stimulation. I'd be really suprised if the NBME tested on it. It's just something you have to memorize.
Isn't miosis related to cholinomimetic/cholinergic agonist/cholinesterase inhibitor response? Antimuscarinic would be mydriasis... am I missing something?
xenophila is offline   Reply With Quote
Old 07-21-2012, 06:55 PM   #6
2K Member
 
Phloston's Avatar
 
Join Date: Jan 2012
Location: Australia
Posts: 2,222
SDN Gold Donor
Default
Quote:
Originally Posted by xenophila View Post
Isn't miosis related to cholinomimetic/cholinergic agonist/cholinesterase inhibitor response? Antimuscarinic would be mydriasis... am I missing something?
Yeah. I was going to let it slide before as I had assumed he just made a typo, but yes, miosis is muscarinic and mydriasis anti-muscarinic.
Phloston is offline   Reply With Quote
Old 07-21-2012, 08:23 PM   #7
1K Member
 
ijn's Avatar
 
Join Date: Nov 2009
Posts: 1,238
SDN 2+ Year Member
Default
Wow, yeah. Man, that kind of stuff slips from your brain so quickly.
ijn is offline   Reply With Quote
Old 07-22-2012, 03:59 AM   #8
SGU MS-2
 
Morsetlis's Avatar
 
Join Date: Jan 2010
Location: St. George's, Grenada
Posts: 4,886
SDN 2+ Year Member
Default
Quote:
Originally Posted by ijn View Post
According to Kaplan pharmacology
Ah mah gawd I finally remember where your avatar comes from
__________________
You must learn from the mistakes of others. You can't possibly live long enough to make them all yourself.
Morsetlis is offline   Reply With Quote

Reply

Bookmarks

« Previous Thread | Next Thread »
Thread Tools
Display Modes
Linear Mode Linear Mode

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -7. The time now is 06:09 AM.


Comments are closed.