Adenosine

U.S. BRAND NAMES — Adenocard®; Adenoscan®
CANADIAN BRAND NAMES — Adenocard®; Adenoscan®; Adenosine Injection, USP
SYNONYMS — 9-Beta-D-ribofuranosyladenine
THERAPEUTIC CATEGORY Antiarrhythmic Agent, Miscellaneous
DOSING — Note: Adequate controlled studies in pediatric patients have not been conducted.
(For additional information see "Adenosine: Drug information")
Manufacturer's recommendations: Rapid I.V.: Neonates, Infants, Children, and Adolescents weighing <50 kg: Initial dose: 0.05-0.1 mg/kg; if not effective within 1-2 minutes, increase dose by 0.05-0.1 mg/kg increments every 1-2 minutes to a maximum single dose of 0.3 mg/kg or until termination of PSVT Children and Adolescents weighing 50 kg and Adults: 6 mg, if not effective within 1-2 minutes, 12 mg may be given; may repeat 12 mg bolus if needed
Alternative pediatric dosing: Neonates: Rapid I.V.: Initial dose: 0.05 mg/kg; if not effective within 2 minutes, increase dose by 0.05 mg/kg increments every 2 minutes to a maximum dose of 0.25 mg/kg or until termination of PSVT Infants and Children: PALS dose for treatment of SVT: Rapid I.V.; I.O.: Initial: 0.1 mg/kg (maximum: 6 mg); if not effective, give 0.2 mg/kg (maximum: 12 mg)
DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Injection, solution [preservative free]: 3 mg/mL (2 mL, 4 mL) Adenocard®: 3 mg/mL (2 mL, 4 mL) Adenoscan®: 3 mg/mL (20 mL, 30 mL)
GENERIC AVAILABLE — Yes
ADMINISTRATION — Parenteral: For rapid bolus I.V. use, administer over 1-2 seconds at peripheral I.V. site closest to patient's heart (I.V. administration into lower extremities may result in therapeutic failure or requirement of higher doses); follow each bolus with NS flush (infants and children: 5-10 mL; adults: 20 mL); if given peripherally in adults, elevate the extremity for 10-20 seconds after the NS flush. To administer doses <600 mcg (0.2 mL of commercial product), a dilution with NS (final concentration: 300 mcg/mL) may be made. Note: Preliminary results in adults suggest adenosine may be administered via a central line at lower doses (eg, Adults: Initial dose: 3 mg); FDA approved labeling for pediatric patients weighing <50 kg states that doses listed may be administered either peripherally or centrally (further studies are needed)
USE — Treatment of paroxysmal supraventricular tachycardia (PSVT); used in adult ACLS algorithms for narrow-complex tachycardias, stable narrow-complex supraventricular tachycardias, and wide-complex tachycardias that are supraventricular in origin; used in PALS algorithms for probable supraventricular tachycardia; investigationally used as a continuous infusion for the treatment of primary pulmonary hypertension in adults and persistent pulmonary hypertension of the newborn (PPHN) (see Additional Information)
ADVERSE REACTIONS Cardiovascular: Flushing, arrhythmias, palpitations, chest pain, bradycardia, heart block, minimal hemodynamic disturbances, hypotension (<1%)
Central nervous system: Irritability, headaches, lightheadedness, dizziness
Gastrointestinal: Nausea, metallic taste
Respiratory: Dyspnea, hyperventilation, bronchoconstriction in asthmatics
CONTRAINDICATIONS — Hypersensitivity to adenosine or any component; second and third degree A-V block or sick sinus syndrome unless pacemaker placed
PRECAUTIONS — Bronchoconstriction may occur in asthmatics (avoid use in patients with bronchospasm or bronchoconstriction); use with caution in patients with underlying dysfunction of sinus or A-V node, obstructive lung disease, and those taking digoxin or verapamil; initial adenosine dose should be significantly decreased in patients receiving dipyridamole
WARNINGS — Heart block, including transient or prolonged asystole may occur as well as other arrhythmias; episodes of asystole or other arrhythmias may be fatal; if arrhythmia is not due to re-entry pathway through A-V node or sinus node (ie, atrial fibrillation, flutter, or tachycardia or ventricular tachycardia), adenosine will not terminate the arrhythmia but can produce transient ventriculoatrial or A-V block; possible mutagenic effects
DRUG INTERACTIONS — Dipyridamole potentiates effects of adenosine (dose of adenosine should be significantly reduced); methylxanthines (aminophylline, theophylline, caffeine) antagonize adenosine's effects so that larger doses of adenosine or an alternative agent may be required; carbamazepine may increase heart block; digoxin and verapamil may cause ventricular fibrillation (rare cases reported)
PREGNANCY RISK FACTOR — C (show table)
MONITORING PARAMETERS — Continuous EKG, heart rate, blood pressure, respirations
STABILITY — Do not refrigerate, precipitation may occur; contains no preservatives, discard unused portion
MECHANISM OF ACTION — Slows conduction time through the A-V node, interrupting the re-entry pathways through the A-V node, restoring normal sinus rhythm
PHARMACODYNAMICS Onset of action: Rapid
Duration: Very brief
PHARMACOKINETICS Metabolism: Removed from systemic circulation primarily by vascular endothelial cells and erythrocytes (by cellular uptake); rapidly metabolized intracellularly; phosphorylated by adenosine kinase to adenosine monophosphate (AMP) which is then incorporated into high-energy pool; intracellular adenosine is also deaminated by adenosine deaminase to inosine; inosine can be metabolized to hypoxanthine, then xanthine and finally to uric acid.
Half-life: <10 seconds
NURSING IMPLICATIONS — Be alert for dyspnea, shortness of breath, and possible exacerbation of asthma
ADDITIONAL INFORMATION — Not effective in atrial flutter, atrial fibrillation, or ventricular tachycardia; short duration of action is an advantage as adverse effects are usually rapidly self-limiting; effects may be prolonged in patients with denervated transplanted hearts. Individualize treatment of prolonged adverse effects: Give I.V. fluids for hypotension, aminophylline/theophylline may antagonize effects.
Limited information is available regarding the use of adenosine for the treatment of persistent pulmonary hypertension of the newborn (PPHN); efficacy, optimal dose, and duration of therapy is not established; a randomized, masked, placebo-controlled pilot study of 18 term infants with PPHN used initial doses of 25 mcg/kg/minute (n=9); after 30 minutes, doses were increased to 50 mcg/kg/minute if no improvement in PaO2 was observed; all patients received study drug via central line into the right atrium (inserted via the umbilical vein); significant improvement in oxygenation was observed in 4 of 9 newborns receiving 50 mcg/kg/minute; hypotension or tachycardia were not observed; further studies are needed (Kondur, 1996).
Adenosine is also available as Adenoscan®, which is used in adults as an adjunct to thallium-201 myocardial perfusion scintigraphy; see package insert for further information on this use.