Clinical Toxicology & Poisoning

Introduction & definitions

• Toxicology — the study of the adverse effects of substances on living organisms; any substance becomes a poison when exposure produces a damaging (toxic) physiological effect. Clinical toxicology studies the undesired effects of drugs in humans and the effects and treatment of poisoning.
• Toxicokinetics & toxicodynamics — toxicokinetics = ADME of toxins / toxic doses of drugs / their metabolites; toxicodynamics = their injurious effects on body function. Toxicokinetics largely parallels pharmacokinetics, but supratherapeutic exposure brings saturation kinetics, altered protein binding and delayed/erratic absorption.
• Hazard vs risk — hazard = the ability of a chemical to cause injury in a given setting (depends on inherent toxicity and amount of exposure); risk = the expected frequency of an undesirable effect, estimated from dose–response data.
• Scale & key principle — over 1 million acute poisonings occur annually in the USA; most deaths are intentional suicidal overdoses in adolescents/adults — yet even serious exposures are rarely fatal if the victim receives prompt medical attention and good supportive care. Children (<6 y) account for most exposures (unintentional/exploratory); adults have the highest fatality rates (intentional).