carmendrahl writes: "Tiny drug doses- 1% of an active dose- are unexpectedly useful in clinical trials. But don't bust out your homeopathic pills. This concept--microdosing-- is a different concept entirely. Studies with microdoses get conducted side-by-side with standard clinical trials to figure out what fraction of the full-size dose actually makes it to the site of action. Scientists at Merck used the technique with five potential new HIV drugs. Possible future applications include determining whether a patient's cancer is likely to respond to certain platinum-based drugs."