Adecard

• Approved Indications:

  • Paroxysmal Supraventricular Tachycardia (PSVT):
  • Rapid conversion to normal sinus rhythm of PSVT, including that associated with accessory bypass tracts (e.g., Wolff-Parkinson-White syndrome).
  • Diagnostic Use:
  • As an adjunct in myocardial perfusion imaging (stress test) to cause coronary vasodilation in patients unable to exercise adequately.

  Important Off-Label (Clinically Accepted) Uses:

  • Diagnostic Aid: Used during electrophysiologic studies to identify arrhythmia mechanisms (e.g., to unmask latent pre-excitation or AV nodal properties).
  • Termination of other reentrant supraventricular tachycardias: In some atrial tachycardias to help distinguish atrial flutter from PSVT.
  • Note: Not effective for atrial fibrillation, atrial flutter, or ventricular arrhythmias.

Route: Rapid IV bolus only. Must be administered via a large-bore IV as close to the heart as possible, followed immediately by a rapid saline flush.

Adults:

• PSVT:
• Initial dose: 6 mg IV rapid push over 1–2 seconds.
• If not effective within 1–2 minutes, give 12 mg IV rapidly.
• A second 12 mg dose may be given if needed.
• Maximum single dose: 12 mg.
• Myocardial Perfusion Imaging:
• 140 mcg/kg/min by continuous IV infusion for 6 minutes.

Pediatrics:

• PSVT:
• Initial: 0.05–0.1 mg/kg IV rapid push (max 6 mg).
• May increase by 0.05–0.1 mg/kg increments every 1–2 minutes to a maximum single dose of 0.3 mg/kg or 12 mg (whichever is lower).

Special Populations:

• Elderly: No specific adjustment; increased sensitivity possible.
• Hepatic/Renal Impairment: No adjustment needed; adenosine is rapidly metabolized in blood and tissues.

Administration Tips:

• Rapid IV push followed immediately by a 20 mL saline flush.
• Patient should be in a supine position with continuous ECG monitoring.
• Emergency resuscitation equipment must be immediately available.

Adenosine is an endogenous purine nucleoside that slows conduction through the atrioventricular (AV) node by activating A1 adenosine receptors. This increases outward potassium currents and hyperpolarizes cardiac cells in the AV node, temporarily blocking conduction and interrupting reentrant circuits involving the AV node. This allows restoration of normal sinus rhythm in reentrant supraventricular tachycardia. In myocardial perfusion imaging, adenosine causes coronary vasodilation by activating A2A receptors, increasing blood flow in normal coronary arteries while diseased vessels remain relatively underperfused, aiding detection of ischemia.

Absorption:

• Not applicable — administered IV only.

Distribution:

• Rapidly distributed in blood and tissue.

Metabolism:

• Rapidly taken up by erythrocytes and vascular endothelial cells.
• Metabolized intracellularly to inosine and then hypoxanthine by adenosine deaminase.

Excretion:

• Metabolites are excreted mainly in urine.
• Plasma half-life: <10 seconds.

Pregnancy:

• FDA Pregnancy Category C. Limited human data suggest no significant risk when used acutely; due to its extremely short half-life, systemic exposure is minimal. Use only if clearly indicated.

Lactation:

• Unknown if excreted in human milk. Because of rapid metabolism and short action, clinically significant exposure to a breastfeeding infant is unlikely. No precautions needed for single-use diagnostic or emergency doses.

• Primary Class: Antiarrhythmic Agent
• Subclass: Endogenous purine nucleoside; class V antiarrhythmic

• Second- or third-degree AV block (unless a functioning artificial pacemaker is in place)
• Sick sinus syndrome (except in patients with a pacemaker)
• Symptomatic bradycardia (without pacemaker)
• Known hypersensitivity to adenosine
• Asthma or severe bronchospasm (relative contraindication for stress testing use)

• Arrhythmias: May cause transient asystole, bradycardia, or new arrhythmias (e.g., atrial fibrillation). Continuous ECG monitoring required.
• Bronchospasm: Can cause severe bronchospasm; contraindicated in reactive airway disease when used as a coronary vasodilator.
• Hypotension: May cause significant hypotension; use with caution in patients with unstable hemodynamics.
• Seizures: Rare cases reported — use with caution in patients with seizure disorders.
• Interactions with Methylxanthines: Caffeine and theophylline block adenosine receptors and reduce its effect — higher doses may be needed.

Common:

• Flushing
• Chest discomfort or tightness
• Dyspnea
• Throat tightness
• Lightheadedness
• Transient arrhythmias (PVCs, brief asystole)

Serious/Rare:

• Sustained bradycardia or asystole (rare, self-limited)
• Bronchospasm
• Hypotension
• Seizures (very rare)

Side effects are usually short-lived due to adenosine’s ultra-short half-life.

• Methylxanthines (e.g., caffeine, theophylline): Antagonize adenosine’s effects; higher doses may be required.
• Dipyridamole: Potentiates adenosine’s effects by inhibiting its cellular uptake; lower doses may be needed.
• Carbamazepine: May increase risk of higher-degree AV block with adenosine.

• ACLS Guidelines: Adenosine remains first-line for acute PSVT not caused by pre-excited atrial fibrillation or flutter.
• NICE & Major Cardiology Societies: Continue to recommend adenosine as the preferred agent for rapid conversion of AV nodal reentrant tachycardia (AVNRT).
• No major regulatory updates; usage remains well established for PSVT and myocardial perfusion imaging.

• Store at 15°C to 30°C (59°F to 86°F).
• Do not refrigerate.
• Protect from excessive heat.
• Use single-dose vials promptly once opened; discard unused portion.