Thursday, April 19, 2018

PDE5 inhibitors

Q: PDE5 inhibitors (Sildenafil, tadalafil or vardenafil) are now increasing used in ICU for the management of pulmonary hypertension. Their mechansim of action is? 

 A) Prolong the vasodilatory effect of nitric oxide 
B) Stimulates the nitric oxide receptor 
C) Selective antagonist of type A endothelin-1 receptor 
D) Nonselective endothelin receptor antagonist 
E) unexplained (found accidentally in patients with erectile dysfunction) 


Phosphodiesterase type 5 (PDE5) inhibitors prolong the vasodilatory effect of nitric oxide.

(Choice B) Riociguat is a Guanylate Cyclase stimulant (sGC) which increases the sensitivity of sGC to endogenous nitric oxide (NO) as well as directly stimulate the receptor to mimic the action of NO.

(choice C) Ambrisentan is an oral selective type A endothelin-1 receptor antagonist.

(Choice D) Bosentan is an oral nonselective endothelin receptor antagonist.



Galiè N, Humbert M, Vachiery JL, et al. 2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension: The Joint Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS): Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC), International Society for Heart and Lung Transplantation (ISHLT). Eur Heart J 2016; 37:67.

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