Emergency Medicine PharmD
Emergency Medicine PharmaD - By Nadia Awad - February 10, 2014
"Nitroglycerin (and other organic nitrates) form free nitric oxide radicals that activate guanylate cyclase, which catalyzes the synthesis of cGMP, leading to smooth muscle relaxation. Using PDE-5 inhibitors in the setting of organic nitrates could potentiate the vasodilatory effects of the latter, leading to profound and potentially life-threatening systemic hypotension...
Even knowing about this interaction you ponder about this some more, and you really and truly believe that nitroglycerin can benefit your patient. So what are you going to do?"
http://empharmd.blogspot.com/2014/02/the-combination-of-pde-5-inhibitors-and.html