Digoxin Toxicity in a Neonate Caused by the Interaction with Carvedilol

Introduction

In infants and children with cardiac defects and heart failure multiple drug therapy is often required and medications is often applied on a non evidence based level. In severe heart failure digoxin is occasionally co-administered with carvedilol and other drugs (Rathnapalan S et al., J Pediatr 2003 May;142 (5): 572–574).

While recent studies show reduced interstage mortality among children with single-ventricle heard disease while using digoxin at discharge (Brown et al., J Am Hear Assoc. 2016; 5: e002376, doi:10.1161/JAHA.115.002376) most information on toxic drug interactions with digoxin is derived from adult studies. Combined therapy of carvedilol and digoxin was found to cause an accumulation of digoxin with elevated serum concentration (Wermeling DP et al., Pharmacotherapie 1994; 14: 600–606; De-Mey C et al., Br J ClinPharmacol 1990; 29: 486–490; Grunden JW et al., Am J Ther 1994; 1: 15–61). In a case series of 8 paediatric patients Rathnapalan et al. described a reduction of digoxin clearance after oral administration (approximately 50%) when combined with carvedilol. Some patients with elevated digoxin serum concentrations showed vomiting as the only sign of digoxin toxicity whereas arrhythmias did not occur (Rathnapalan S et al., J Pediatr 2003 May; 142 (5): 572–574).

Presented within this case we describe neonatal digoxin intoxication after co-administration of carvedilol leading to severe and potentially harmful arrhythmias.