Abstract
Digoxin is the oldest cardiovascular drug and it has been used over the past 200 years for the treatment of heart failure. A serum digoxin level O 3.0 nmol/l (2.5 ng/ml) is considered to be toxic.
The aim of our study was to analyze a patient population with toxic serum digoxin levels, paying particular attention to drug interactions and characteristics associated with patient mortality. Central biochemistry databases from two teaching hospitals in Prague, Czech Republic identified 222 medical patients with a serum digoxin level GREATER-THAN OR EQUAL TO3.0 nmol/ml between 2001 and 2005.
Baseline characteristics of our cohort of 222 patients with a serum digoxin level GREATER-THAN OR EQUAL TO3.0 nmol/ml are shown in tab.1. Total mortality until discharge was 8.1%.
Cardiac mortality directly attributable to digoxin toxicity was reported in 1.8% of cases. Statistically significant predictors of mortality included low creatinine clearance with p=0.02 (Odds Ratio 0.95) which can be explained by digoxin pharmacokinetics +- 70% of digoxin content is eliminated from the human body unchanged by active kidney processes in those with normal renal function.
Concomitant medication analysis has shown that 64% of patients were prescribed at least one drug with a known interaction that directly increase the serum digoxin level. Seven percent of patients were taking three or more drugs with known drug interaction.
Drug interactions were analyzed in detail and every single drug was analyzed in relation to survival. The only statistically significant difference was identified with the concomitant use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB), which seems to have a protective effect (13.46% mortality without concomitant ACEI/ARB and 3.57% mortality in patients on ACEI/ARB treatment, p=0.01) The potassium level could not be used to predict an outcome.