Viagra vs. Cialis?

Twenty-four hour duration in erectile responsiveness for Lilly/Icos' Cialis "may or may not be a good thing...in light of the nitrate interaction" with phosphodiesterase inhibitors, McKinnell cautions. Meanwhile, Pfizer CEO acknowledges that Cialis' 16 minutes to onset of action "does appear to be maybe faster by one hour" than Viagra, but questions whether the difference is meaningful