In vivo zebrafish assays for toxicity testing.

Toxicity, due to complications of in vivo adsorption, distribution, metabolism and excretion (ADME), is a major cause of failure during drug development; many drugs shown to be safe in cell culture prove toxic in animal studies. Effective in vivo toxicity screening early in the development process can reduce the number of compounds that progress to laborious and costly late-stage animal testing. The transparent zebrafish provides accessibility to internal organs, tissues and even cells, and has emerged as an invaluable model organism for toxicity testing and drug discovery. Straightforward in vivo zebrafish assays can serve as an intermediate step between cell-based and mammalian testing, thus streamlining the drug development time-line.