Procardia acts to relax the pulmonary arteries. It is the only drug that I know of that reverses symptoms of HAPE after they start to develop. From osmotic pressure, some fluid goes from the alveoli into the lungs. As the lungs fill with fluid, it becomes harder and harder to breathe. After awhile a coma and then death can result.
Descent is the best solution, although oxygen can help the symptoms when descent is impossible.
I have always been a bit slow at high altitude. At first I put it down to the lack of oxygen. Sometime I remembered some odd breathing sounds when I was over 10,000 feet for a weekend. I never got headaches worse than headaches that I sometimes get while hiking. I have never felt nauseated.