Sildenafil should not be used in: (A) Diabetics, (B) Patients on vasodilator therapy, (C) Pulmonary hypertension, (D) Erectile dysfunction
Answer is B. Sildenafil inhibits PDE-5 and prevents Nitric oxide (NO) degradation. Increased NO results in vasodilation. It should not be used in patients taking vosodilators as it can lead to sudden hypotension.