Which statement indicates a misunderstanding of sildenafil (Viagra) use?

The statement indicating a misunderstanding of sildenafil (Viagra) use is that it's safe to mix with nitroglycerin. This is a crucial point because sildenafil, a phosphodiesterase type 5 (PDE-5) inhibitor, can cause significant vasodilation. When taken in conjunction with nitroglycerin, which is also a potent vasodilator, there is a risk of a dangerous drop in blood pressure. Therefore, patients using sildenafil should be warned against using it simultaneously with any medication containing nitrates, as this combination can lead to serious cardiovascular complications.

In contrast, the other statements accurately reflect the appropriate use and considerations for sildenafil. It does enhance sexual performance for individuals experiencing erectile dysfunction, it can be safely prescribed to men over the age of 40, and while primarily indicated for erectile dysfunction, it is also used in some cases for pulmonary arterial hypertension under different brand names.