Final answer:
Combining nitrates and sildenafil can cause a severe drop in blood pressure, which may lead to life-threatening conditions like heart attacks and strokes. Men with cardiac disease taking nitrates should avoid sildenafil or consult their doctor to prevent potential adverse effects.
Step-by-step explanation:
If a patient takes both nitrates and sildenafil, there is a significant risk of a dangerous interaction that can lead to a severe drop in blood pressure. Nitrates, such as nitroglycerin, are medications prescribed for the treatment of heart conditions like angina pectoris. They work by releasing nitric oxide (NO), which diffuses across the plasma membrane and causes blood vessels to dilate, improving blood flow to the heart. Sildenafil, known commercially as Viagra®, is a phosphodiesterase 5 (PDE5) inhibitor that also promotes vasodilation but is primarily used to treat erectile dysfunction (ED). The drug was initially tested for heart conditions, but it was not effective for that purpose and was subsequently approved for ED.
The combined effect of both nitrates and sildenafil on vasodilation can result in excessive blood vessel dilation, causing a sharp decrease in blood pressure. This hypotensive effect can be life-threatening, leading to symptoms like dizziness, fainting, heart attack, or stroke. Consequently, it's critical for men with cardiac disease taking nitrates to avoid using sildenafil or consult their physician for safe medication strategies. There have been deaths reported for at-risk users who combined these substances, highlighting the importance of medical guidance in such cases.