Toxicity

Toxicity encompasses adverse effects produced by chemical, physical, or biological agents on living organisms, ranging from mild reversible changes to severe irreversible organ damage or death, representing critical safety consideration throughout pharmaceutical development, environmental assessment, and clinical practice. Toxicity manifestations depend on multiple factors including dose, exposure duration, administration route, individual susceptibility, and agent-specific mechanisms.

The pharmaceutical industry conducts extensive toxicology studies throughout development identifying potential adverse effects, establishing safe starting doses for first-in-human trials, supporting dose escalation decisions, and informing risk-benefit assessments. Preclinical toxicity testing employs two species with acute studies assessing single-dose effects, repeated-dose studies evaluating extended administration, and specialised studies addressing reproductive toxicity, genotoxicity, and carcinogenic potential. Safety pharmacology examines effects on vital organ systems. Mechanistic toxicology investigations identify cellular and molecular mechanisms enabling biomarker development. Clinical safety monitoring detects toxicities through adverse event reporting, laboratory monitoring, and systematic assessments. Predictive toxicology employs in silico modelling, in vitro assays, and omics approaches identifying toxicity risks earlier in development. As understanding advances through mechanism elucidation, technologies improve enabling better prediction, and alternative methods reduce animal use, toxicology continues evolving supporting safer therapeutic development.