Answer:
Sildenafil is the drug used to treat the pulmonary arterial hypertension and erectile dysfunction. The side effects of this drug are flushed skin, headaches and heartburn.
The nitroglycerine and sildenafil interferes with the NO mechanism of the body. The nitrates are always contraindicated with sildenafil because they can cause a severe decrease in the blood pressure of an individual. The decrease in blood pressure helps to treat the problem of hypertension.