Maybe it increases blood flow to the genitals and that adds enjoyment. I would think the sides would be any different for a woman.
I did read where it is a pulmonary vasodilator and it is being used in patients with pulmonary hypertension. And with some success and very little sides and you can imagine they are having it administered around the clock, men and women with little sides as I recall or much safer than the other drugs they have had to use before.