A recent study found that Cialis (Tadalafil) was nearly as effective as Dexamethasone for prevention of HAPE in the HAPE-susceptible:

http://www.annals.org/content/145/7/497.full.pdf+html


And it would seem that the consensus opinion is still that Nifedipine is effective at both preventing and treating HAPE:

http://books.google.com/books?id=NG21K80G_04C&pg=PA811&lpg=PA811&dq=nifedipine+%2BHAPE
http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter-2/altitude-illness.aspx

http://www.mpoullis.net/bsphysiol/altitu...tm#HAPE-therapy

I'd like to see a study comparing all 3 drugs, that would be worthwhile.