Recommendation: In the newborn with atrial flutter, initial therapy with digoxin has been the traditional approach. However, this has never been demonstrated to be any more efficacious than primary electrical cardioversion.[16]
Safety
In all age groups, digoxin is associated with a neutral effect on mortality in randomised trials and a lower rate of admissions to hospital across all study types.[22] However, in a meta-analysis of hospital adverse drug reactions (ADRs), the mean fatal ADR prevalence varied from 0.01% in paediatric patients to 0.44% in the elderly. Warfarin, aspirin, renin-angiotensin system inhibitors and digoxin accounted for 60% of fatal ADRs.[23]
Ventricular fibrillation following adenosine therapy for SVT in a neonate with concealed Wolff-Parkinson-White syndrome treated with digoxin has been reported.[24]
Digoxin toxicity may originate from or be exacerbated by drug interactions. Inhibitors of P-glycoprotein (ABCB1) such as verapamil, amiodarone or macrolide antibiotics can enhance oral bioavailability of digoxin by decreasing its efflux from the enterocytes into the lumen of the intestine and decrease its active tubular secretion into the urine in the kidney. As a result, plasma concentrations of digoxin may significantly increase to toxic levels [see drug interactions]. Recommended window of therapeutic concentrations is quite narrow (0.8–2.0 ng/mL) and more recent recommendations suggest even lower and more narrow range (0.5–1.0 ng/mL).[25]
Increased arrhythmic complications have been identified in patients with serum digoxin concentrations ≥1.2 ng/mL. If used in the context of any renal impairment, digoxin requires very careful dose and level monitoring to prevent toxicity.[1]
Hypokalaemia increases the incidence of arrhythmias and sudden cardiac death. The risk is increased in patients with pre-existing heart disease and in those treated with digoxin.
Although cases of digoxin poisoning are fewer than those involving calcium channel and beta blockers, the mortality rate from digoxin is far greater.
Specific antidote therapy with digoxin-specific antibody fragments (digoxin-Fab) should be used if there are arrhythmias associated with haemodynamic instability. Digoxin-Fab interferes with digoxin immunoassay measurement and can lead to overestimation of plasma digoxin concentrations.[26]
Lanoxin Paediatric Elixir contains approximately 52 mg/mL of propylene glycol and 84 mg/mL of ethanol, equivalent to 10.6% absolute volume (email correspondence with the manufacturer on 21st March 2019). Long-term effects of prolonged exposure to ethanol content are unknown.
| 