Chapter 5: Toxicology Principles and the Treatment of Poisoning

The text establishes a framework for treating poisoned patients through five critical steps: providing immediate cardiopulmonary support, performing decontamination to remove the toxin, identifying the causative agent, administering specific antidotes, and maintaining supportive care. A significant portion of the discussion analyzes agricultural toxicants, distinguishing between herbicides like 2,4-D, which can uncouple oxidative phosphorylation, and the highly toxic bipyridyl compounds paraquat and diquat, which generate free radicals leading to lipid peroxidation, pulmonary edema, and renal failure. The summary further examines insecticides, contrasting the acetylcholinesterase-inhibiting properties of organophosphates and carbamates—which provoke cholinergic crises requiring atropine and pralidoxime—with the neurotoxic effects of organochlorines (DDT) and pyrethroids that disrupt sodium ion channels. The section on heavy metal toxicity details the systemic pathologies caused by lead, mercury, and arsenic, such as heme synthesis interference and central nervous system damage, while explaining the pharmacology of chelating agents like calcium disodium EDTA, dimercaprol, unithiol, and succimer that bind metals for excretion. Finally, the text addresses environmental and occupational hazards, covering the hypoxic mechanisms of carbon monoxide via carboxyhemoglobin formation, the carcinogenic and bone marrow-suppressing effects of hydrocarbons like benzene, and the respiratory toxicity of air pollutants including ozone and nitrogen dioxide.