Avoid taking zudena 100 at the same time as nitrate medications if you are taking them for heart problems or chest pain. This includes nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate. Furthermore, nitrates are present in a number of recreational drugs, such as amyl nitrate or nitrite ("poppers"). In combination with a nitrate medication, udenafil has the ability to precipitously and dramatically reduce blood pressure.