ADENOSINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ADENOSINE (ADENOSINE).
Adenosine is an endogenous purine nucleoside that acts as a non-selective agonist at adenosine A1, A2A, A2B, and A3 receptors. It slows atrioventricular (AV) conduction through activation of A1 receptors, which increases potassium efflux and reduces calcium influx, hyperpolarizing nodal cells and prolonging refractoriness. This terminates reentrant supraventricular tachyarrhythmias involving the AV node.
| Metabolism | Primarily metabolized by adenosine deaminase (ADA) to inosine; also phosphorylated to adenosine monophosphate (AMP) by adenosine kinase. Rapidly cleared from circulation (half-life <10 seconds). |
| Excretion | Hepatic metabolism (primarily via adenosine deaminase and adenosine kinase) to inosine and AMP; renal excretion of metabolites accounts for <10% of elimination. |
| Half-life | Terminal elimination half-life <10 seconds (rapidly cleared from plasma by cellular uptake and metabolism); clinical context: transient effects require continuous IV infusion for sustained action. |
| Protein binding | 0% (negligible binding to plasma proteins). |
| Volume of Distribution | 0.04-0.1 L/kg (reflects rapid uptake into erythrocytes and endothelial cells, not true tissue distribution). |
| Bioavailability | Intravenous: 100% (only route with clinical effect). Oral: <3% due to extensive first-pass metabolism; not used clinically. |
| Onset of Action | Intravenous: <30 seconds (immediate bolus effect). Intraosseous: similar to IV. Intramuscular/subcutaneous: not clinically used; negligible absorption due to rapid metabolism. |
| Duration of Action | Intravenous: 10-20 seconds (for AV nodal reentrant tachycardia); effects resolve within 1-2 minutes due to rapid clearance. |
| Action Class | Miscellaneous agents- anti arrhythmic |
| Brand Substitutes | Adenoject 3mg Injection, Adenocor 3mg Injection, Adnet 3mg Injection |
Paroxysmal supraventricular tachycardia: 6 mg rapid IV bolus over 1-2 seconds; if no conversion in 1-2 minutes, give 12 mg rapid IV bolus; may repeat 12 mg once if necessary. Maximum single dose: 12 mg. Also used for cardiac stress testing: 140 mcg/kg/min IV infusion over 6 minutes, total dose 0.84 mg/kg.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment. Adenosine is rapidly metabolized in blood and endothelial cells; negligible renal excretion. |
| Liver impairment | No dose adjustment required for hepatic impairment. Metabolism is predominantly by intracellular adenosine deaminase in erythrocytes and vascular endothelium, not hepatic enzymes. |
| Pediatric use | Paroxysmal supraventricular tachycardia: First dose: 0.1 mg/kg IV rapid bolus (maximum 6 mg). If no conversion in 1-2 minutes, second dose: 0.2 mg/kg (maximum 12 mg). Minimum weight: not specified. |
| Geriatric use | No specific dose adjustment based on age alone. Use same dosing as adults; monitor for hypotension and bradycardia due to potential age-related decreased baroreceptor sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ADENOSINE (ADENOSINE).
| Breastfeeding | It is unknown if adenosine is excreted in human breast milk. Due to its very short half-life (<10 seconds) and rapid metabolism, systemic exposure to an infant via breast milk is expected to be negligible. The American Academy of Pediatrics considers adenosine compatible with breastfeeding. M/P ratio: not available. |
| Teratogenic Risk | Adenosine is classified as FDA Pregnancy Category C. Animal studies have shown adverse effects on the fetus (including increased fetal resorptions and skeletal anomalies) at doses higher than human therapeutic doses. No adequate and well-controlled studies exist in pregnant women. Due to its short half-life and rapid metabolism, the risk of teratogenicity from brief exposure is considered low, but it should be used only if clearly needed. First trimester: potential risk based on animal data; second and third trimesters: limited data, theoretical risk of uterine blood flow reduction. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Second- or third-degree AV block (except in patients with a functioning artificial pacemaker)","Sick sinus syndrome (except with pacemaker)","Known hypersensitivity to adenosine","Atrial fibrillation or atrial flutter with an accessory bypass tract (risk of ventricular pre-excitation and rapid ventricular response)"]
| Precautions | ["Cardiac arrest, ventricular fibrillation, torsade de pointes, and other fatal arrhythmias have occurred, particularly in patients with underlying heart disease or those receiving other cardioactive drugs.","May cause severe bradycardia, sinus arrest, or heart block; transient asystole may occur.","Bronchospasm in patients with asthma or COPD; use with caution and have rescue bronchodilators available.","Hypotension, flushing, dyspnea, and chest pain are common but transient.","Seizures (rare) reported, especially with high doses or in elderly."] |
| Food/Dietary | Avoid caffeine-containing foods and beverages (coffee, tea, cola, chocolate) for at least 12 hours before adenosine administration as caffeine is a competitive antagonist. Theophylline also antagonizes adenosine; ensure patients on theophylline are advised to withhold it 24 hours prior if possible. |
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| Fetal Monitoring | Continuous ECG monitoring is required during administration due to risk of transient asystole, bradycardia, and other arrhythmias. Blood pressure should be monitored frequently. In pregnancy, fetal heart rate monitoring should be considered, especially at higher doses, due to potential for transient fetal bradycardia or hypoxia. |
| Fertility Effects | No studies have been conducted on the effect of adenosine on human fertility. Animal studies have not revealed evidence of impaired fertility at clinically relevant doses. There are no known adverse effects on reproductive organs or gametogenesis. |
| Clinical Pearls | Administer as a rapid IV bolus followed by a 20 mL saline flush to maximize first-pass cardiac effect. Monitor for transient asystole and AV block; resuscitation equipment must be available. Adenosine can induce bronchospasm in asthmatics; use with caution. Dose reduction (e.g., 3 mg) may be considered if given via central line or in patients on dipyridamole or carbamazepine. Caffeine and theophylline antagonize adenosine effects; avoid prior consumption. |
| Patient Advice | You may experience a brief period of chest pressure, shortness of breath, or flushing after the injection; these sensations usually last less than a minute. · It is common to feel a temporary stopping or slowing of your heartbeat; you will be closely monitored. · Avoid caffeine-containing products (coffee, tea, cola, chocolate) and theophylline medications for at least 12 hours before your procedure. · Inform your healthcare provider if you have asthma, COPD, or heart block. |