Question

Your patient is prescribed a nitrate-based anti-hypertensive medication (e.g. nitroglycerin) to reduce his blood pressure. You ask him if he takes erectile dysfunction medications such as Viagra. Why is this an important question? What may happen to the patient if he takes both medications?

Answer 1

Nitroglycerines used as antihypertensive drugs act by increasing the cAMP in vascular smooth muscle to cause dilation of vessels.

Sildenafil, sold under the brand name of viagra for erectile dysfunction is a phosphodiesterase inhibitor which inhibits the degradation of cAMP . Due to increased cAMP there is penile vasodilation and increased blood flow cause erection.

But when both the drugs are taken together there is strong vasodilation in body due to very much increase in cAMP. This can increase the risk of postural hypotension and sudden fall can cause trauma.