After you discover it worked once. You give high doses to lab rats and keep reducing the dose until it quits killing them. Then you give it to infected rats in ever smaller doses until it quits curing them. The effective dose is somewhere in that range between doesn’t work and kills you.
Step two is to extrapolate the quantity to humans and work from the minimum effective dose up to the point it turns the whites of your eyes blue.
However, this is all academic because with the Obama Health Plan there won’t be any research that matters.
It’s easier on the rats if you work up from the small doses...