Drug Guide
Adenosine
Classification
Therapeutic: Antiarrhythmic agent, Diagnostic agent (myocardial perfusion imaging)
Pharmacological: Nucleoside, Adenosine receptor agonist
FDA Approved Indications
- Conversion of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm
- Myocardial perfusion imaging (Adenoscan)
Mechanism of Action
Adenosine acts on A1 receptors in the heart to inhibit adenylyl cyclase, increasing potassium efflux and hyperpolarizing cardiac cells. This results in temporary AV nodal block, which can terminate reentrant supraventricular tachycardias. In myocardial perfusion imaging, adenosine causes vasodilation of coronary arteries, increasing blood flow for imaging purposes.
Dosage and Administration
Adult: 6 mg rapid IV push; may repeat with 12 mg and 12 mg if needed, at 1-2 minute intervals. Must be administered as a rapid IV push followed immediately by a saline flush.
Pediatric: Not typically used; limited data. Use with caution and under specialist guidance.
Geriatric: Adjust dose as needed; increased sensitivity and predisposition to adverse effects.
Renal Impairment: Use with caution; no specific dose adjustment established.
Hepatic Impairment: Limited data; use cautiously.
Pharmacokinetics
Absorption: Not applicable; administered IV.
Distribution: Wide distribution in tissues, crossing the blood-brain barrier.
Metabolism: Rapidly metabolized mainly by erythrocytes and vascular endothelium via adenosine deaminase.
Excretion: Renal excretion of metabolites.
Half Life: Less than 10 seconds, due to rapid metabolism.
Contraindications
- Second- or third-degree AV block unless functioning ventricular pacemaker
- Sick sinus syndrome unless a functioning pacemaker
- History of hypersensitivity to adenosine
Precautions
- Use with caution in asthma or bronchospasm, as adenosine can cause bronchoconstriction
- Monitor closely during administration; may cause hypotension, chest discomfort, or bronchospasm
Adverse Reactions - Common
- Flushing (Common)
- Chest pain, pressure, or tightness (Common)
- Headache (Common)
- AV block or asystole (Less common)
Adverse Reactions - Serious
- Bronchospasm in asthmatic patients (Uncommon but serious)
- Severe hypotension or arrhythmias (Rare)
Drug-Drug Interactions
- Theophylline (antagonist, reduces adenosine effects)
- Dipyridamole (potentiates adenosine effects)
Drug-Food Interactions
- None significant
Drug-Herb Interactions
- None significant
Nursing Implications
Assessment: Monitor cardiac rhythm continuously during and after administration. Watch for bronchospasm or hypotension.
Diagnoses:
- Risk for decreased cardiac output
- Anxiety related to arrhythmia episodes
Implementation: Administer as prescribed, ensure IV access is patent, have resuscitation equipment ready.
Evaluation: Observe for termination of arrhythmia or adverse reactions; ensure patient stability.
Patient/Family Teaching
- Report chest pain, unusual shortness of breath, or severe dizziness.
- Inform that feeling of flushing or chest discomfort is common and usually temporary.
- Explain the procedure if used for diagnostic imaging, including temporary nature of effects.
Special Considerations
Black Box Warnings:
- No specific black box warnings for adenosine.
Genetic Factors: Limited data; no known genetic considerations.
Lab Test Interference: Adenosine can cause transient changes in ECG readings.
Overdose Management
Signs/Symptoms: Severe bradycardia, AV block, hypotension, bronchospasm.
Treatment: Discontinue infusion immediately; provide supportive care, oxygen, IV fluids, vasopressors if needed, and resuscitation as necessary.
Storage and Handling
Storage: Store at room temperature, protected from light.
Stability: Stable for up to 24 months when stored properly.