Allergy to class/drug
Concurrent regular or intermittent use of any organic nitrates
Concomitant use with HIV protease inhibitors or elvitegravir/cobicistat/tenofovir/emtricitabine
Concomitant use with riociguat or any other guanylate cyclase stimulator
Sildenafil
Acebutolol
Amlodipine
Bosentan
Hydralazine
Epoprostenol 
Tropicamide
Timolol