Concerned by a system in which more than nine out of 10 experimental drugs fail when tested in humans, the Food and Drug Administration issued suggestions Thursday on how researchers can more efficiently evaluate the promise of new laboratory discoveries.

The vast majority of drug candidates fail once they're tested on humans, invariably for safety or efficacy reasons difficult to predict based on initial experiments done in test tubes and on animals. That can waste significant amounts of time and money, slowing the process of developing new drugs.

The goal of the new approaches being floated by the FDA is to guide researchers on methods of identifying early-on those drug candidates that are most likely to succeed once early testing in humans gets under way. Those so-called exploratory investigational new drug studies typically involve very limited numbers of subjects given small amounts of a drug for brief periods.

The new advice also offers approaches for safely producing the small batches of drugs needed for initial tests. Given the limited scope of early trials, the manufacturing requirements should be less burdensome than they are for drugs already on the market, according to the FDA.

The suggestions are part of what the regulatory agency calls its critical path initiative, which refers to the journey a drug takes from laboratory to patient. The initiative, introduced in 2004, aims to improve the efficiency and safety of the development of drugs and other medical products.

The recommendations will help more researchers conduct earlier, more-informed studies of promising treatments so patients have more rapid access to safer and more effective drugs, said Mike Leavitt, secretary of the health and Human Services Department.

The documents also explain the flexibility in the amount of data the FDA requires from researchers before it will allow them to undertake early testing in humans. That too in theory could speed the drug development process.

Those requirements represent one of the biggest barriers faced by researchers in their attempts to move a new discovery from the lab into human testing, said Dr. Andrew von Eschenbach, the FDA's acting commissioner.

Taking full advantage of the flexibility FDA offers could spur researchers in the development of tailor-made drugs for individual patients, von Eschenbach added.