Adenosine Half-Life
Adenosine has an extremely short half-life of less than 10 seconds in whole blood. 1
Pharmacokinetics and Metabolism
- Adenosine is rapidly cleared from plasma through cellular uptake, primarily by erythrocytes and vascular endothelial cells, via a specific transmembrane nucleoside carrier system 1
- Once inside the cell, adenosine is rapidly metabolized either via phosphorylation to adenosine monophosphate by adenosine kinase, or via deamination to inosine by adenosine deaminase in the cytosol 1
- The extremely short half-life contributes to adenosine's safety profile, as any adverse effects typically resolve quickly once administration is discontinued 1
- Excessive amounts of adenosine may be deaminated by an ecto-form of adenosine deaminase 1
Clinical Implications of Short Half-Life
- The brief duration of action allows for rapid titration of doses when treating supraventricular tachycardia (SVT), as effects dissipate quickly if a dose is ineffective 2
- Serious adverse effects are rare because of the drug's very short half-life, though patients commonly experience transient side effects such as chest discomfort, shortness of breath, and flushing 3
- Due to its short half-life, adenosine does not prevent reinitiation of SVT, and early recurrence of tachycardia is observed in up to one-third of treated patients 4
- The rapid metabolism makes adenosine particularly suitable for diagnostic applications in tachycardia evaluation, as effects quickly resolve 2
Special Considerations
- Adenosine's metabolism is independent of renal or hepatic function, so dose adjustments are not required in patients with renal or hepatic impairment 1
- Methylxanthines such as caffeine, aminophylline, and theophylline are competitive adenosine receptor antagonists and can reduce adenosine's effectiveness 1
- Dipyridamole and carbamazepine can potentiate adenosine's effects, requiring dose reduction 5
- During intravenous adenosine infusion for diagnostic purposes (e.g., fractional flow reserve measurement), patients should avoid Valsalva maneuvers as this can interrupt continuous drug delivery 3
Comparison with Other Antiarrhythmics
- Unlike calcium channel blockers or beta-blockers, adenosine does not cause prolonged depression of myocardial contractility due to its ultra-short half-life 5
- Compared to verapamil for treating SVT, adenosine has a more rapid onset and shorter duration of action, with less potential for serious hemodynamic adverse effects 6
The extremely short half-life of adenosine makes it an ideal agent for both therapeutic and diagnostic cardiovascular applications, allowing for rapid termination of effects if adverse reactions occur while still providing effective treatment for appropriate arrhythmias.