___________ is the pharmacokinetics of a drug under conditions that produce toxicity or excessive exposure.

• A. Toxicokinetics
• B. Pharmacokinetics
• C. Toxicodynamics
• D. Pharmacovigilance

Answer: (A)

Toxicokinetics describes how the body handles a drug when there is toxicity or excessive exposure. It applies pharmacokinetic principles to overdose or poisoning, where absorption, distribution, metabolism, and excretion can behave differently—often becoming nonlinear due to enzyme saturation or impaired elimination. This leads to disproportionate rises in drug levels and longer persistence in the body, which is critical for predicting concentrations and guiding toxic-dose management, antidotes, or decontamination timing. By contrast, pharmacokinetics covers normal ADME behavior, toxicodynamics focuses on the harmful effects and mechanisms once exposure occurs, and pharmacovigilance involves detecting and reporting adverse drug reactions.