Adenosine (IV — SVT Termination)

Verbatim source wording (UK SPC §4.2, Posology, Adult): 'Initial dose: 3mg given as a rapid intravenous bolus (over 2 seconds). Second dose: If the first dose does not result in elimination of the supraventricular tachycardia within 1 to 2 minutes, 6mg should be given also as a rapid intravenous bolus. Third dose: If the second dose does not result in elimination of the supraventricular tachycardia within 1 to 2 minutes. 12mg should be given also as a rapid intravenous bolus. Additional or higher doses are not recommended.' NOTE FOR REVIEWERS: this SPC schedule is 3 mg then 6 mg then 12 mg. SETTING (§4.2): 'intended for hospital use only with monitoring and cardiorespiratory resuscitation equipment available for immediate use'; 'should only be used when facilities exist for cardiac monitoring'. STOP RULE (§4.2): 'Patients who develop high-level AV block at a particular dose should not be given further dosage increments.' ELDERLY (§4.2): 'See dosage recommendations for adults.' DIAGNOSTIC USE (§4.2): 'The above ascending dosage schedule should be employed until sufficient diagnostic information has been obtained. Method of administration: Rapid intravenous injection only.' PREPARATION (§4.2): each vial is for single use; 'The solution should be examined visually for particulate matter and discoloration prior to administration. Only clear and colourless solution should be used.' DIPYRIDAMOLE (§4.4): 'As dipyridamole is a known inhibitor of adenosine uptake, it may potentiate the action of Adenosine... It is therefore suggested that Adenosine 3 mg/ml solution for injection should not be administered to patients receiving dipyridamole; if use of Adenosine 3 mg/ml solution for injection is essential, dipyridamole should be stopped 24 hours before hand, or the dose of Adenosine 3 mg/ml solution for injection should be greatly reduced.' PERSISTENT SIDE EFFECTS (§4.8): 'Methylxanthines, such as IV aminophylline or theophylline have been used to terminate persistent side effects (50-125 mg by slow intravenous injection).' CAUTIONS (§4.4) include left main coronary stenosis, uncorrected hypovolaemia, stenotic valvular heart disease, left to right shunt, pericarditis or pericardial effusion, autonomic dysfunction, stenotic carotid artery disease with cerebrovascular insufficiency, recent myocardial infarction, severe heart failure, minor conduction defects (first degree AV block, bundle branch block), atrial fibrillation or flutter (especially with an accessory bypass tract, which 'may develop increased conduction down the anomalous pathway'), and recent heart transplantation (less than 1 year), where 'an increased sensitivity of the heart to adenosine has been observed'.

Verbatim source wording (UK SPC §4.2, Paediatric population): 'The dosing recommended for the treatment of paroxysmal supraventricular tachycardia in the paediatric population is: - first bolus of 0.1 mg/kg body weight (maximum dose of 6mg) - increments of 0.1 mg/kg body weight as needed to achieve termination of supraventricular tachycardia (maximum dose of 12mg).' The 0.1 mg/kg figure is therefore a per-DOSE figure (both the first bolus and each increment), not a daily total. The concentration figure of 3 mg per mL is the strength of the sourced product itself ('Adenosine 3 mg/ ml solution for injection') — CHECK THE STRENGTH OF THE VIAL IN YOUR HAND before using any calculated volume. SAFETY (§4.2): 'During administration of adenosine cardio-respiratory resuscitation equipment must be available for immediate use if necessary. Adenosine is intended for use with continuous monitoring and ECG recording during administration.' Verify against a children's formulary and local paediatric resuscitation guidance before use.