A simple method to determine the elimination half-life of drugs displaying noncumulative toxicity

The pharmacokinetic characterization of a drug, especially the determination of its biological half-life, is an essential step during the early phases of drug development. An adequate half-life is amongst the many properties needed for selecting a drug candidate for clinical trials. Conversely, drug candidates possessing inadequate half-lives may be modified or eliminated from the drug discovery pipeline altogether. Several methods exist for determining the half-lives of drugs, namely HPLC, fluorescence assays, radioassays, radioimmunoassays, and elemental mass spectrometric assays. However, all these techniques are resource and labor-intensive, and cannot be used for the high-throughput half-life determination of hundreds of drug candidates. Here, we describe TOX: a simple technique to determine the half-lives of compounds displaying noncumulative toxicity. To calculate the half life, TOX only relies on the survival outcomes of three experiments performed on an animal model: an acute toxicity experiment, a cumulative toxicity experiment, and a multi-dose experiment at different dosing intervals. As a proof of concept, we use TOX to determine the peritoneal half-life of Ω76, an antimicrobial peptide. The half-life of Ω76 determined by TOX is in good agreement with results from a standard mass spectrometric method, validating this approach.