Antidotes & reversal agents
The reversal agent for each drug class that has one — a high-yield NCLEX table. Learn the principle (which antidote and why); confirm the drug and dose against current guidelines before administering.
15 antidotes
Drug class / toxin Antidote / reversal agent
Acetylcysteine (NAC / Mucomyst)
Replenishes glutathione to neutralize toxic NAPQI; most effective within ~8 h of overdose.
Anticholinergics (Atropine)
Autonomic
Physostigmine
For severe anticholinergic toxicity — "hot as a hare, dry as a bone, red as a beet, mad as a hatter, blind as a bat."
Anticoagulants
Cardiovascular High-alert
Protamine sulfate (heparin) · Vitamin K / phytonadione (warfarin)
Dabigatran → idarucizumab; apixaban/rivaroxaban → andexanet alfa. Protamine ~1 mg per 100 units heparin (max 50 mg per 10 min).
Benzodiazepines
Nervous
Flumazenil
Competitive benzodiazepine antagonist — reverses sedation/respiratory depression. Use cautiously: it can precipitate seizures or acute withdrawal in benzodiazepine-dependent or chronic-use patients.
Cardiac Glycosides (Digoxin)
Cardiovascular High-alert
Digoxin immune Fab (DigiFab)
Binds and inactivates digoxin; reverses life-threatening toxicity — refractory dysrhythmias, severe bradycardia, or hyperkalemia from acute overdose.
Cholinergic Agonists
Autonomic
Atropine
Blocks muscarinic receptors — reverses cholinergic excess (SLUDGE) and the accompanying bradycardia in a cholinergic crisis.
General & Local Anesthetics
Nervous
20% lipid emulsion (LAST rescue) · dantrolene (malignant hyperthermia)
IV 20% lipid emulsion is the "lipid sink" antidote for local anesthetic systemic toxicity (LAST); dantrolene stops the runaway calcium release of malignant hyperthermia. Both must be immediately available wherever triggering agents are used.
Insulins
Endocrine High-alert
Hypoglycemia rescue — 15 g fast-acting carb if conscious; D50 IV or glucagon IM if unconscious
"Rule of 15": treat, recheck glucose in 15 min, repeat. Not a drug antidote but the NCLEX-critical rescue.
Iron / Anemia Agents
Hematologic
Deferoxamine
Iron-chelating antidote for acute iron overdose — a leading cause of fatal poisoning in young children.
Magnesium Sulfate (Obstetric)
Reproductive & OB High-alert
Calcium gluconate
Reverses magnesium toxicity (respiratory/cardiac depression). Keep at the bedside during the infusion.
Mood Stabilizers (Lithium)
Nervous High-alert
No specific antidote
Toxicity → hold, hydrate, correct sodium; hemodialysis for severe toxicity.
Neuromuscular Blockers
Nervous High-alert
Neostigmine (or sugammadex)
Reverses nondepolarizing blockade only — neostigmine (an AChE inhibitor, give with an antimuscarinic) raises ACh to outcompete the blocker; sugammadex directly encapsulates rocuronium/vecuronium. Depolarizing succinylcholine is not reversible this way. For malignant hyperthermia, give dantrolene immediately.
Opioid Analgesics
Nervous High-alert
Naloxone (Narcan)
Pure competitive µ-opioid antagonist; reverses respiratory depression. Short half-life — monitor for re-sedation and repeat as needed.
Tricyclic Antidepressants (TCAs)
Nervous
Sodium bicarbonate (IV)
For overdose cardiotoxicity — TCAs are lethal in overdose (narrow therapeutic index): cardiac sodium-channel blockade widens the QRS (> 100 ms) and causes ventricular arrhythmia. IV sodium bicarbonate overcomes the block. Limit dispensed quantities in at-risk patients.
Vasopressors & Inotropes
Cardiovascular High-alert
Phentolamine
An α-blocker infiltrated locally for extravasation — reverses the intense alpha-mediated vasoconstriction that otherwise causes tissue ischemia and necrosis.
Only classes with a specific reversal agent appear here. Many drugs have no antidote — for those, management is supportive (stop the drug, treat symptoms). See each class page for the full picture.