ADENOSCAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ADENOSCAN (ADENOSCAN).
Adenosine is a purine nucleoside that acts as a coronary vasodilator by activating A2A adenosine receptors on vascular smooth muscle, causing hyperemia. It also slows atrioventricular (AV) nodal conduction via A1 receptor activation.
| Metabolism | Rapidly metabolized by adenosine deaminase in erythrocytes and vascular endothelium to inosine and then to uric acid, with a half-life <10 seconds. |
| Excretion | Primarily renal excretion of metabolites; <3% excreted unchanged in urine. Adenosine is rapidly metabolized intracellularly to inosine and adenosine monophosphate, with further degradation to uric acid. <2% eliminated in feces. |
| Half-life | < 10 seconds (biphasic: distribution half-life < 1 second, terminal elimination half-life ~0.6-1.5 seconds). Clinically, effects are rapidly terminated due to cellular uptake and metabolism. |
| Protein binding | < 10% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Estimated ~0.4 L/kg (small, reflecting limited tissue binding and rapid elimination). |
| Bioavailability | Bioavailability: Not applicable for oral; for IV: 100%. |
| Onset of Action | Intravenous bolus: within seconds (maximal coronary vasodilation at 30 seconds). Continuous IV infusion: sustained effect achieved within 2-3 minutes. |
| Duration of Action | Intravenous bolus: coronary hyperemia lasts < 2 minutes. Continuous infusion: duration as long as infusion continues, with rapid offset (< 1 minute) upon discontinuation. |
Intravenous administration at 140 mcg/kg/min for 6 minutes (total dose 0.84 mg/kg).
| Dosage form | SOLUTION |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for mild to moderate hepatic impairment; not studied in severe hepatic impairment. |
| Pediatric use | Not approved for pediatric use; efficacy and safety not established. |
| Geriatric use | No specific dosage adjustment; caution due to increased sensitivity to hemodynamic effects (e.g., hypotension). |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ADENOSCAN (ADENOSCAN).
| Breastfeeding | It is not known whether adenosine is excreted in human milk. Due to its short half-life (<10 seconds) and rapid metabolism, systemic exposure in a nursing infant is expected to be negligible. Caution is advised; consider the developmental and health benefits of breastfeeding along with the mother's clinical need for the drug. M/P ratio not established. |
| Teratogenic Risk | Adenosine (Adenoscan) is classified as FDA Pregnancy Category C. Animal studies have shown an increased incidence of skeletal variations and reduced fetal weight at doses 10-20 times the human dose. No well-controlled studies in pregnant women. Use only if potential benefit justifies potential risk to fetus. First trimester: theoretical risk due to A2A receptor involvement in embryonic development. Second and third trimesters: risk of maternal hypotension and reduced uterine blood flow. |
■ FDA Black Box Warning
Risk of cardiac arrest, myocardial infarction, and death. Fatal cardiac events have occurred. Adenosine should only be used in settings with appropriate resuscitation equipment and personnel.
| Serious Effects |
["Known hypersensitivity to adenosine","Second- or third-degree AV block (unless a functioning pacemaker is present)","Sick sinus syndrome (unless a functioning pacemaker is present)","Known or suspected bronchoconstrictive or bronchospastic lung disease (e.g., asthma, COPD)","Concurrent use of dipyridamole or carbamazepine (due to risk of prolonged effects)"]
| Precautions | ["May cause severe hypotension, bradycardia, and heart block; use with caution in patients with sick sinus syndrome or advanced AV block","May induce bronchoconstriction; avoid in patients with reactive airway disease (e.g., asthma, COPD) unless benefit outweighs risk","May cause new or worsened arrhythmias, including atrial fibrillation, ventricular tachycardia, and asystole","Use caution with drugs that inhibit adenosine metabolism (e.g., dipyridamole) or increase sensitivity (e.g., methylxanthines)"] |
| Food/Dietary |
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| Fetal Monitoring | Continuous ECG monitoring during administration due to risk of AV block, sinus pause, and arrhythmias. Blood pressure monitoring for hypotension. Fetal heart rate monitoring should be considered in pregnant patients due to potential for reduced uteroplacental perfusion. |
| Fertility Effects | Adenosine has not been studied for effects on human fertility. Animal studies showed no impairment of fertility at doses up to 20 times the human dose. By transiently increasing cyclic AMP levels, adenosine may affect sperm motility or acrosome reaction, but clinical significance is unknown. |
| Avoid caffeine-containing foods and beverages (including coffee, tea, cola, energy drinks, chocolate) for at least 12-24 hours before the adenosine stress test, as caffeine is an adenosine receptor antagonist and can attenuate the drug's vasodilatory effects. Also avoid theophylline-containing products. No other food interactions are known. |
| Clinical Pearls | Adenosine is a potent vasodilator used for pharmacologic stress testing in patients unable to exercise. Administer as a continuous IV infusion at 140 mcg/kg/min for 6 minutes; stress imaging is performed during the infusion. Monitor for heart block, bronchospasm, and hypotension. Administer aminophylline (50-125 mg IV) if severe adverse effects occur. Avoid in patients with second- or third-degree AV block, sick sinus syndrome (unless paced), bronchospastic lung disease, or hypersensitivity to adenosine. Caffeine and theophylline antagonize adenosine effects; withhold for at least 12-24 hours before test. |
| Patient Advice | You will receive this medication through an IV line while you are lying down and connected to monitors. · You may feel chest pressure, shortness of breath, flushing, or a headache during the infusion; these effects usually resolve quickly after the infusion stops. · Your heart rate and blood pressure will be closely monitored throughout the test. · Do not consume any caffeine (coffee, tea, soda, chocolate) or take theophylline medications for at least 12 to 24 hours before your test as they can interfere with the results. · Inform your healthcare provider if you have asthma, severe lung disease, or a slow heart rate, as this medication may not be safe for you. |