Overdosereversal

Overdosereversal refers to clinical interventions aimed at reversing the physiologic effects of an overdose of a toxic substance, with the goal of restoring adequate organ function and preventing death. Reversal may be accomplished with specific antidotes, the best-known example being naloxone for suspected opioid overdose. Naloxone displaces opioids at mu receptors and can be administered by emergency responders or trained laypersons via intramuscular, intravenous, or intranasal routes; repeat dosing may be necessary due to differences in opioid pharmacokinetics.

Other antidotes include flumazenil for benzodiazepine overdose, though its use is limited due to risk of seizures or arrhythmias in co-ingestions or benzodiazepine-dependent patients. Specific toxin antidotes include N-acetylcysteine for acetaminophen poisoning, fomepizole or ethanol for methanol or ethylene glycol poisoning, and pralidoxime with atropine for organophosphate poisoning. For calcium channel blocker or beta-blocker overdose, supportive care and agents such as calcium, glucagon, or vasopressors may be used; there is no universal antidote.

General measures accompany antidotal therapy: securing the airway, ventilation support, cardiovascular stabilization, and continuous monitoring. Decontamination and toxin removal, such as activated charcoal within a short time window, may be considered in appropriate cases; dialysis can be indicated for certain toxins.

Public health aspects include the availability of naloxone to bystanders, training programs, and harm-reduction strategies to reduce overdose mortality. Limitations include the risk of precipitated withdrawal, recurrent overdose due to longer-acting agents, and the possibility of incomplete reversal in mixed or poly-substance overdoses.