Antidotes for Common Medication Toxicities

With Renal & Hepatic Dose Considerations (Adult & Pediatric)

Offending Medication / Toxin (A–Z) Antidote Adult Dose (Summary) Pediatric Dose (Summary) Renal Considerations Hepatic Considerations & Clinical Pearls
Acetaminophen N-Acetylcysteine (NAC) IV 21-h protocol (weight-based) Same No adjustment required Safe in hepatic failure; continue NAC until AST/ALT improve
Anticholinergics Physostigmine 0.5–2 mg IV slow 0.02 mg/kg (max 0.5 mg) No adjustment Avoid in hepatic encephalopathy; seizures risk ↑
Benzodiazepines Flumazenil 0.2 mg IV titrated 0.01 mg/kg (max 0.2 mg) No adjustment Avoid in chronic liver disease with BZD dependence
Beta-blockers Glucagon 3–10 mg IV bolus → infusion 0.05–0.15 mg/kg No adjustment Causes hyperglycemia; monitor in cirrhosis
Calcium Channel Blockers Calcium salts / HIET Ca gluconate 10–20 mL IV 60 mg/kg (max 3 g) No adjustment HIET safe in hepatic failure
Carbon Monoxide 100% Oxygen NRB / hyperbaric Same N/A Pregnancy = lower hyperbaric threshold
Cyanide Hydroxocobalamin 5 g IV 70 mg/kg (max 5 g) No adjustment Interferes with LFTs; safe in liver failure
Digoxin Digoxin Immune Fab Level-based or empiric Same Fab–digoxin complexes renally cleared → prolonged effect in CKD No hepatic adjustment
Heparin (UFH) Protamine 1 mg per 100 units Same No adjustment Caution in liver disease with coagulopathy
Isoniazid Pyridoxine (Vit B6) Gram-for-gram ingested 70 mg/kg (max 5 g) No adjustment Essential in hepatic toxicity; continue supportive care
Iron Deferoxamine 15 mg/kg/h IV Same Avoid prolonged use in CKD (AKI risk) Hepatic impairment ↑ hypotension risk
Local Anesthetic (LAST) Lipid emulsion 20% 1.5 mL/kg bolus → infusion Same No adjustment Safe in hepatic disease
Methemoglobinemia Methylene Blue 1–2 mg/kg IV Same Use caution in CKD Avoid in severe hepatic disease & G6PD deficiency
Methanol / Ethylene Glycol Fomepizole 15 mg/kg → 10 mg/kg q12h Same Increase frequency during dialysis No hepatic adjustment
Opioids Naloxone 0.04–2 mg IV/IM/IN 0.1 mg/kg (max 2 mg) No adjustment Shorter half-life than opioids—monitor in cirrhosis
Organophosphates Atropine + Pralidoxime Atropine titrated; pralidoxime 1–2 g IV Weight-based Reduce pralidoxime dose in severe CKD Hepatic metabolism minimal
Salicylates Sodium bicarbonate 1–2 mEq/kg IV Same Risk of volume overload in CKD Hepatic disease ↑ alkalosis risk
Sulfonylureas Octreotide 50–100 mcg SC q6–12h 1–2 mcg/kg No adjustment Caution in cirrhosis (glucose dysregulation)
TCAs Sodium bicarbonate 1–2 mEq/kg IV Same Monitor Na⁺ in CKD Avoid alkalosis in severe liver failure
Warfarin Vitamin K ± PCC Vit K 5–10 mg IV 0.5–2 mg IV PCC preferred in CKD Liver disease → INR less predictive of bleeding
Xanthines (theophylline) Activated charcoal (MDAC) Multiple-dose Weight-based Dialysis preferred in CKD Hepatic failure ↑ toxicity risk

High-Yield Clinical Pearls for Hospital Pharmacists

  • Supportive care is the true “antidote” in many overdoses.
  • Timing matters more than drug levels for many antidotes (e.g., NAC, fomepizole).
  • Avoid flumazenil unless absolutely indicated.
  • HIET is underutilized but life-saving in CCB/BB toxicity.
  • Always reassess renal/hepatic function for antidote dosing.
  • Consult toxicology early for severe or unclear poisonings.

Monitoring Checklist

Parameter Why
ECG / QRS / QTc Cardiotoxic agents (TCAs, digoxin, CCBs)
ABGs / Lactate Metabolic acidosis (toxic alcohols, CO)
LFTs Acetaminophen
Electrolytes Digoxin, insulin, phosphate, calcium
Glucose HIET, sulfonylureas, insulin

Renal Failure

  • Dialyzable toxins (salicylates, methanol, ethylene glycol, theophylline) → antidote + dialysis
  • Fab fragments, fomepizole, pralidoxime may accumulate in CKD
  • Watch volume overload with bicarbonate therapy

Hepatic Failure

  • NAC remains beneficial even after liver injury
  • INR may not correlate with bleeding risk
  • Avoid agents causing hepatic encephalopathy or seizures
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