ACLS Pharmacology
A small set of drugs appears again and again across the ACLS algorithms. Knowing each drug's dose, route, and indication cold lets you support the team without slowing the code.
Arrest drugs: epinephrine and antiarrhythmics
Epinephrine 1 mg IV/IO every 3 to 5 minutes is used in every cardiac arrest; its vasoconstriction raises aortic diastolic and coronary perfusion pressure. In non-shockable rhythms (asystole/PEA) give it as early as possible; in shockable rhythms (VF/pVT) give it after the initial shocks fail. For shock-refractory VF/pVT, add an antiarrhythmic: amiodarone 300 mg IV/IO first dose then 150 mg, or lidocaine 1 to 1.5 mg/kg first dose then 0.5 to 0.75 mg/kg. These antiarrhythmics are layered on top of, not instead of, continued defibrillation and CPR.
Rate and rhythm drugs: atropine and adenosine
Atropine 1 mg IV every 3 to 5 minutes (maximum 3 mg total) is first-line for symptomatic bradycardia; it reduces vagal tone to increase the heart rate, and if ineffective you escalate to transcutaneous pacing or a dopamine/epinephrine infusion. Adenosine 6 mg rapid IV push (then 12 mg if needed) is used for stable, regular, narrow-complex SVT after vagal maneuvers fail; its ultra-short action briefly blocks the AV node to interrupt a re-entrant circuit. Always give adenosine as fast as possible followed by a rapid saline flush because it is metabolized within seconds.