There is no doubt that ADME/Tox drug properties, absorption, distribution, metabolism, elimination and toxicity, are properties crucial to the final clinical success of a drug candidate. It has been estimated that nearly 50% of drugs fail because of unacceptable efficacy, which includes poor bioavailability as a result of ineffective intestinal absorption and undesirable metabolic stability(1). It has also been estimated that up to 40% of drug candidates have failed in the past because of safety issues(2). In this review, the methodologies that are available for use in drug development as in vitro human-based screens for ADME/Tox drug properties are discussed.