An equal if indirect source of human suffering is the opportunity cost of abandoning promising drugs because of misleading animal tests.68 As candidate drugs generally proceed down the development pipeline and to human testing based largely on successful results in animals69 (i.e., positive efficacy and negative adverse effects), drugs are sometimes not further developed due to unsuccessful results in animals (i.e., negative efficacy and/or positive adverse effects). Because much pharmaceutical company preclinical data are proprietary and thus publicly unavailable, it is difficult to know the number of missed opportunities due to misleading animal experiments. However, of every 5,000–10,000 potential drugs investigated, only about 5 proceed to Phase 1 clinical trials.70 Potential therapeutics may be abandoned because of results in animal tests that do not apply to humans.71 Treatments that fail to work or show some adverse effect in animals because of species-specific influences may be abandoned in preclinical testing even if they may have proved effective and safe in humans if allowed to continue through the drug development pipeline.
