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NBME 21 Answers

nbme21/Block 2/Question#39 (43.9 difficulty score)
A 64-year-old man with bronchospastic ...
Enhanced action of the agonist at β-adrenergic receptors🔍

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194orbust  per UWorld, "cortisol exerts a permissive effect on many hormones to help improve the response to a variety of stressors. For example, cortisol increases vascular and bronchial smooth muscle reactivity to catecholamines". FA also uses the effect of cortisol on catecholamine responsiveness as the lone example for a permissive drug interaction (FA2018 pg 229). The difference here is that we're talking about exogenous glucocorticoid and adrenergic agonist. I guess it was expected for us to assume that the mechanism is analogous for the analogous drugs +3  
maxillarythirdmolar  I'm sure it's related to the activating effect of Cortisol on phenylethanolamine-N-methyltransferase, converting NE to Epi. Sounds like a synergistic thing to me. (FA.83) +3  
feeeeeever  My logic is probably flawed, but I also thought that if cortisol has the ability inhibit COX, LOX, and NFKB you can reduce inflammation and bronchoconstrictive mediators. Therefore, the B2 agonists would have a greater effect since things like LTB4 will be reduced. +1  
feeeeeever  *LTC4, LTD4, LTE4 for bronchoconstriction, my bad +1  

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sahusema  In short, cortisol upregulates adrenergic receptors and makes them more sensitive +  

 +2  upvote downvote
submitted by adong(80),

FA19 p.233 cortisol has a permissive effect on catecholamines

 +1  upvote downvote
submitted by sam1(13),
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kevin  It's permissive because without cortisol Epi wouldn't be able to attain its full effect +