In cardiac arrest, high-quality CPR and early defibrillation save lives; drugs are secondary. No drug should delay compressions or a shock. Drugs aim to raise coronary and cerebral perfusion pressure during CPR, make ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) less likely to recur after a shock, and correct specific reversible causes.
| Drug | Mechanism | Role in resuscitation |
|---|
| Epinephrine (adrenaline) — prototype | Alpha-1 vasoconstriction raises aortic diastolic pressure → better coronary and cerebral perfusion during CPR; beta effects increase heart rate and contractility | All cardiac arrest rhythms |
| Amiodarone | Class III antiarrhythmic: blocks potassium channels (also sodium, calcium, beta) → prolongs repolarization | Shock-refractory VF/pVT; stable wide-complex tachycardia |
| Lidocaine | Class Ib: blocks sodium channels in ischemic ventricular tissue | Alternative to amiodarone for refractory VF/pVT |
| Magnesium sulfate | Stabilizes the membrane; suppresses early afterdepolarizations | Torsades de pointes; hypomagnesemia |
| Atropine | Muscarinic blocker → removes vagal slowing of the SA and AV nodes | Symptomatic bradycardia (not used in cardiac arrest) |
| Adenosine | Briefly blocks AV node conduction (seconds) → interrupts reentry | Stable regular narrow-complex tachycardia (SVT) |
| Calcium chloride / gluconate | Stabilizes cardiac membranes against high potassium | Hyperkalemia, calcium channel blocker overdose, hypocalcemia, hypermagnesemia |
| Sodium bicarbonate | Buffers acid; raises serum sodium and pH | Hyperkalemia, tricyclic antidepressant overdose, severe pre-existing metabolic acidosis |
Adult cardiac arrest (2025 AHA guidelines; the same principles are taught worldwide)
| Rhythm | Drug sequence |
|---|
| VF / pVT (shockable) | Defibrillate as soon as possible → CPR 2 minutes → rhythm check. Epinephrine 1 mg IV/IO every 3–5 minutes after initial defibrillation attempts fail (commonly after the second shock). For refractory VF/pVT: amiodarone 300 mg IV/IO push, then 150 mg, or lidocaine 1–1.5 mg/kg, then 0.5–0.75 mg/kg (maximum 3 mg/kg) |
| Asystole / PEA (non-shockable) | CPR + epinephrine 1 mg IV/IO as soon as feasible, then every 3–5 minutes; no shock; search for reversible causes |
| Torsades de pointes | Defibrillate if pulseless; magnesium sulfate 1–2 g IV/IO diluted, given over minutes (slower if a pulse is present) |
Reversible causes — the H's and T's: hypovolemia, hypoxia, hydrogen ion (acidosis), hypo-/hyperkalemia, hypothermia; tension pneumothorax, tamponade, toxins, thrombosis (pulmonary or coronary). Cause-specific drugs:
- Hyperkalemia: calcium chloride 10% (1 g) or calcium gluconate 10% (about 3 g) IV, sodium bicarbonate, insulin with glucose
- Opioid-associated emergency: naloxone for a person with a pulse and depressed breathing; in arrest, CPR comes first and naloxone may be given
- Suspected massive pulmonary embolism: thrombolytic (e.g., alteplase), with prolonged CPR afterward
- Local anesthetic systemic toxicity: IV lipid emulsion 20%
- Tricyclic overdose with wide QRS: sodium bicarbonate
- Hypoglycemia: IV dextrose
Drugs not recommended routinely in arrest: vasopressin (may be considered but offers no advantage alone or added to epinephrine — do not substitute it for epinephrine), high-dose epinephrine, and routine calcium, sodium bicarbonate, or magnesium without a specific indication. Atropine is not used for asystole or PEA.
Periarrest rhythms (adult)
| Situation | Drug |
|---|
| Symptomatic bradycardia (hypotension, altered mental status, chest pain, acute heart failure, shock) | Atropine 1 mg IV, repeat every 3–5 minutes, maximum 3 mg. If ineffective: transcutaneous pacing, or epinephrine infusion 2–10 mcg/min or dopamine 5–20 mcg/kg/min |
| Stable regular narrow-complex tachycardia | Vagal maneuvers → adenosine 6 mg rapid IV push with an immediate 20 mL saline flush, then 12 mg if needed |
| Stable wide-complex tachycardia | Amiodarone 150 mg IV over 10 minutes (repeat as needed), then infusion, or procainamide (avoid in prolonged QT or heart failure); adenosine only if regular and monomorphic; expert consultation |
| Unstable tachycardia with a pulse | Synchronized cardioversion — do not delay for drugs |
After return of spontaneous circulation (ROSC): vasopressor infusion (norepinephrine or epinephrine) to keep mean arterial pressure ≥ 65 mmHg; oxygen titrated to SpO₂ 90–98% (avoid hypoxemia and hyperoxia); PaCO₂ 35–45 mmHg; temperature control 32–37.5 °C for at least 36 hours in comatose survivors; 12-lead ECG for possible coronary occlusion; glucose control.
Pediatric doses (weight-based; verify with a length-based tape or pediatric reference)
| Drug | Dose |
|---|
| Epinephrine (arrest) | 0.01 mg/kg IV/IO (0.1 mL/kg of 0.1 mg/mL), maximum 1 mg, every 3–5 minutes |
| Amiodarone (refractory VF/pVT) | 5 mg/kg bolus (maximum 300 mg), may repeat up to 3 total doses |
| Lidocaine | 1 mg/kg loading dose |
| Atropine (bradycardia from vagal tone or AV block) | 0.02 mg/kg (maximum single dose 0.5 mg) |
| Adenosine | 0.1 mg/kg (maximum 6 mg), then 0.2 mg/kg (maximum 12 mg) |
| Defibrillation | 2 J/kg, then 4 J/kg; later shocks ≥ 4 J/kg, maximum 10 J/kg or the adult dose |
In children, most arrests are respiratory in origin — oxygenation and ventilation are the priority, and bradycardia with poor perfusion despite ventilation (heart rate below 60/min) is treated with CPR and epinephrine.
| Drug | Key adverse effects |
|---|
| Epinephrine | Tachycardia, dysrhythmias (VF recurrence), hypertension after ROSC, myocardial ischemia; tissue necrosis if an infusion extravasates |
| Amiodarone | Hypotension and bradycardia (IV), phlebitis (concentrated peripheral infusion), QT prolongation; long-term oral use → pulmonary toxicity, thyroid and liver injury |
| Lidocaine | CNS toxicity: perioral numbness, tinnitus, slurred speech, confusion, seizures; bradycardia and asystole at high levels |
| Magnesium | Flushing, hypotension, bradycardia; at high levels loss of reflexes and respiratory depression |
| Atropine | Tachycardia, dry mouth, urinary retention, blurred vision, confusion (older adults); may worsen ischemia |
| Adenosine | Brief asystole (seconds), flushing, chest pressure, dyspnea, sense of doom; bronchospasm |
| Calcium chloride | Severe tissue necrosis if extravasated (central line preferred); bradycardia if given too fast; precipitates with bicarbonate in the same line |
| Sodium bicarbonate | Hypernatremia, metabolic alkalosis, hypokalemia, fluid overload; inactivates catecholamines in the same line |
- In cardiac arrest there is no absolute contraindication to epinephrine — the harm of withholding it is greater
- Epinephrine concentration errors are dangerous: the arrest dose is 1 mg of 0.1 mg/mL (1 mg/10 mL) IV/IO. The 1 mg/mL concentration is for IM use in anaphylaxis and must never be given IV push undiluted
- Atropine: less effective after heart transplant (denervated heart) and in Mobitz II or complete heart block with wide QRS — go to pacing
- Adenosine: caution in asthma (bronchospasm); use 3 mg as the first dose via a central line, after heart transplant, or with dipyridamole or carbamazepine; theophylline and caffeine reduce its effect; not for irregular or polymorphic wide-complex tachycardia (can trigger VF in pre-excited atrial fibrillation)
- Amiodarone: caution in hypotension and bradycardia; additive QT prolongation with other QT drugs; raises warfarin and digoxin levels (long-term)
- Lidocaine: reduce maintenance dosing in heart failure, liver disease, and older adults
- Calcium: caution in digoxin toxicity (historical concern of worsening arrhythmias — give only for life-threatening hyperkalemia per provider)
- Do not mix calcium and sodium bicarbonate in the same line (precipitate); flush between drugs
- Beta-blocker overdose responds poorly to catecholamines — glucagon and high-dose insulin may be ordered
Listed in priority order.
- Start high-quality CPR immediately — rate 100–120/min, depth 5–6 cm (2–2.4 in) in adults, full recoil, minimal interruptions; switch compressors every 2 minutes
- Mechanical CPR devices (AHA 2025): not recommended for routine use in adult cardiac arrest, because trials show no survival difference from manual CPR. They may be considered in specific settings where high-quality manual compressions are difficult or dangerous for staff, provided interruptions during placement and removal of the device are kept to a strict minimum
- Defibrillate shockable rhythms as soon as possible; resume compressions immediately after the shock
- Vascular access: IV first; IO if IV attempts fail or are not feasible. The endotracheal route is a last resort (absorption is unreliable; about 2–2.5 times the IV dose for drugs that can be given this way)
- Give each drug as an IV push followed by a 20 mL saline flush and raise the limb for 10–20 seconds (peripheral line) so it reaches the central circulation
- Prepare the next drug during the 2-minute CPR cycle so it is ready at the rhythm check; announce drug, dose, and time aloud (closed-loop communication)
- Record every drug, dose, time, rhythm, and shock; the recorder prompts the 3–5-minute epinephrine interval
- Monitor end-tidal CO₂ (capnography): a value below 10 mmHg suggests poor compressions; an abrupt rise (often above 35–40 mmHg) suggests ROSC
- Adenosine technique: large antecubital vein, two-syringe or stopcock method, push over 1–2 seconds and flush immediately; run a rhythm strip; warn the client about brief chest pressure and flushing; have the defibrillator ready
- Atropine: monitor heart rate and blood pressure; prepare pacing pads before the first dose in high-grade block
- Amiodarone or lidocaine infusion after ROSC: continuous ECG, blood pressure, QT; watch for CNS signs of lidocaine toxicity
- Post-ROSC care: arterial line and MAP target, oxygen and ventilation targets, glucose, electrolytes (potassium, magnesium), temperature control, neurologic assessment
- Crash cart checks per policy: drug expiry, correct concentrations, defibrillator function
Education is for survivors, families, and the community:
- Recognize cardiac arrest (unresponsive, not breathing normally) → call emergency services, start hands-only CPR, use an AED as soon as available
- Survivors: take antiarrhythmics exactly as prescribed; keep ICD follow-up appointments; report fainting, palpitations, or shocks from the device
- Clients receiving adenosine: expect a brief feeling of chest pressure, flushing, or "the heart stopping" — it passes within seconds
- Amiodarone at discharge: report new cough or breathlessness; use sun protection; keep thyroid, liver, and lung function appointments
- Families present during resuscitation should be offered support and a staff member to explain events
- Lidocaine toxicity (or other local anesthetic systemic toxicity): stop the drug, treat seizures with a benzodiazepine, support airway; IV lipid emulsion 20% for severe toxicity or arrest
- Epinephrine excess or accidental IV injection of 1 mg/mL: severe hypertension, tachydysrhythmias, chest pain, pulmonary edema — stop, monitor, treat dysrhythmias; short-acting agents per provider
- Epinephrine, norepinephrine, dopamine (boxed warning for extravasation), or calcium extravasation: stop the infusion; phentolamine infiltrated locally for catecholamine extravasation
- Atropine (anticholinergic) toxicity: "hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter" — supportive care; physostigmine only in selected cases
- Magnesium toxicity: loss of deep tendon reflexes, respiratory depression — calcium gluconate IV
- Amiodarone hypotension or bradycardia: slow the infusion, fluids, vasopressor or pacing as ordered
- Adenosine effects last seconds; persistent bronchospasm is treated with a bronchodilator
- CPR and defibrillation come first; drugs never delay compressions or shocks
- Epinephrine 1 mg IV/IO every 3–5 minutes: as soon as feasible in asystole/PEA; after initial shocks fail in VF/pVT
- Refractory VF/pVT: amiodarone 300 mg then 150 mg, or lidocaine 1–1.5 mg/kg then 0.5–0.75 mg/kg
- Asystole/PEA: no shock, no atropine — CPR, epinephrine, and the H's and T's
- Torsades → magnesium sulfate 1–2 g
- Vasopressin is not a substitute for epinephrine; routine calcium, bicarbonate, and magnesium are not recommended
- IV first, IO second; push each drug with a 20 mL flush and raise the arm
- Symptomatic bradycardia: atropine 1 mg (max 3 mg) → pacing or epinephrine/dopamine infusion
- SVT: adenosine 6 mg rapid push + flush, then 12 mg; caution in asthma
- 1 mg/mL epinephrine is never pushed IV
- Abrupt ETCO₂ rise = likely ROSC
- Post-ROSC: MAP ≥ 65 mmHg, SpO₂ 90–98%, temperature control 32–37.5 °C
- Pediatric epinephrine 0.01 mg/kg (max 1 mg); defibrillation 2 then 4 J/kg
Country Notes
United States
- Hospital resuscitation follows the 2025 AHA Guidelines for CPR and Emergency Cardiovascular Care; nurses in acute and critical care commonly hold current BLS and ACLS (and PALS for pediatrics) certification.
- Prefilled syringes of epinephrine 0.1 mg/mL are standard in crash carts; many hospitals remove 1 mg/mL vials from non-anesthesia areas to prevent IV errors.
Philippines
- The drug is usually called adrenaline (epinephrine); the same weight-based and standard adult doses apply.
- Hospital nurses commonly train in BLS and ACLS courses based on AHA guidelines; check that crash cart concentrations match the doses used, because stocks may include 1 mg/mL ampules that must be diluted for IV use.