Clarithromycin induced digoxin toxicity.

Abstract

A case of digoxin poisoning following the co-administration of digoxin and clarithromycin in a 28 year old male is described. Since the aetiology of chronic digoxin poisoning is often unclear, clinicians should be aware of the potential drug-drug interaction between digoxin and clarithromycin. (7Accid Emerg Med 1998;15:194-195) ,umol/l, digoxin 5.0 ng/ml (normal therapeutic range 0.5 to 1.2 ng/ml). His last digoxin dose had been 20 hours before presenting to the emergency department.He was rehydrated and placed on telemetry. Digoxin specific Fab fragments were available at the bedside. Clarithromycin was withheld along with digoxin. His renal function remained unchanged during his admission and his digoxin level fell steadily to 3.4 ng/ml the following day, reaching a nadir of 1.2 ng/ml six days after admission. He was treated with sulphamethoxazole-trimethoprim for his pneumonia without adverse effects, and was discharged six days after admission on digoxin, frusemide, and captopril. Subsequent follow up visits revealed normal digoxin levels.

Inhibition of P-glycoprotein–Mediated Efflux of Digoxin and Its Metabolites by Macrolide Antibiotics

“…There have been a number of clinical cases of erythromycin-, clarithromycin-, and roxithromycin-related digoxin toxicity noted in the literature (5,10,11,14). In all cases cessation of digoxin and the macrolide resulted in a resolution of digoxin toxicity and a fall in digoxin levels.…”

“…Hyperkalaemia, a hallmark of acute intoxication due to paralysis of the sodium-potassium ATPase pump, is often absent in chronic intoxication. In such cases hypokalaemia is more likely to occur due to chronic blockade of this ATPase in the nephrons, allowing renal excretion of excess extracellular potassium, in addition to the frequent concomitant use of potassium wasting diuretics (5).…”

“…Several factors are reported to modify the sensitivity of the myocardium to digoxin, which can enhance digitalis toxicity, such as electrolyte imbalances, decreased lean body mass and co-administration of quinidine, amiodarone, verapamil, erythromycin, and diuretics. All these factors may interact and their inter-relationships are likely to determine the presence and extent of digitalis toxicity (3,5).…”