The FDA has formally issued new guidelines designed to speed the testing of experimental drugs on volunteers.
New rules will allow drugmakers to test "minute doses" of experimental drugs to determine if full-blown clinical tests are warranted.
This "micro-dosing" of small numbers of patients in a clinical environment is intended to replace some early experimentation currently done on animals, and is expected to be more accurate.
Experts claim the amount -- about 1 percent of the final dose -- would allow them to determine if the drug gets to the area of the body intended, and how a patient tolerates it.
However, critics have charged that the new guidelines would increase hazards for volunteers, and facilitate the approval of drugs before their risks were fully understood.