[jwbwater]

Anyone that has ever taken a class in molecular biology or biophysics knows that it's ridiculously complex. Many drugs that look promising in vivo or in animals fail to perform in humans. Empirical evidence is what counts. Even targeted enzyme inhibitors are made by a shotgun approach. Synthesize 1000s of candidates and try them all to see which ones work best in vivo and then try those in animals and then try those winners in humans.