Educational use only. Drug cards are AI-assisted study material for NCLEX preparation.
Mechanism of action
Briefly slows conduction through the AV node, interrupting reentrant tachycardias that use the AV node as part of the circuit. Half-life is < 10 seconds. Used for diagnosis and termination of paroxysmal supraventricular tachycardia (PSVT) and as a diagnostic tool for narrow-complex tachycardias.
Adverse effects
Life-threatening / NCLEX-tested
- Brief but profound asystole (typically a few seconds — expected and self-resolving)
- Bronchospasm — caution or avoid in asthma/COPD
- Atrial fibrillation can develop transiently after a dose
- Hypotension
- Severe heart block (rare; usually transient)
- Chest pain or pressure during the dose
Side effects
Common — what to teach
- Sense of impending doom or chest discomfort (very common, transient — warn the patient!)
- Flushing
- Brief headache
- Dyspnea
- Nausea
Food & drug interactions
Theophylline and caffeine block the adenosine receptor — patients on theophylline or who recently had a large caffeine dose may need higher adenosine doses. Dipyridamole and carbamazepine potentiate the effect — reduce dose. Pacemakers may be reset transiently.
Nursing implications
Assessment, monitoring, patient teaching
- Always on continuous ECG monitoring; have crash cart and ACLS drugs immediately available
- Use a 2-syringe technique: rapidly push the adenosine bolus IV in a proximal large vein, then immediately flush with 10–20 mL saline rapidly — slow administration will not work
- Standard dose: 6 mg first; if no response in 1–2 minutes, 12 mg; may repeat 12 mg once
- WARN the patient before pushing: brief chest pressure, flushing, sense of doom, then a few seconds of asystole, then normal rhythm — "it will feel terrible for ~10 seconds and then pass"
- Print rhythm strip during administration for documentation
- Cautious use in asthma — bronchospasm risk; have a beta agonist available
When to hold / contraindications
- Second- or third-degree AV block (without pacemaker)
- Sick sinus syndrome (without pacemaker)
- Severe asthma or active bronchospasm
- Known hypersensitivity
- Wide-complex tachycardia of uncertain origin (depending on protocol — check ACLS guidelines)
Memory anchor
"6, 12, 12 — push fast, flush fast." Half-life under 10 seconds. Warn the patient before the push: brief chest squeeze and "sense of doom," then back to normal.
Practice Adenosine questions
Test your recall on real NCLEX-style pharmacology questions — with full rationales and an AI Coach for the parts you miss.