Postmortem redistribution of digoxin in rats

Adult male Wistar rats were treated with either 0.1 or 3 mg/kg body weight·day of digoxin for five days, then killed and stored at 4°C for 12 h in an attempt to mimic the normal preautopsy procedures in our hospital. In rats treated with 0.1 mg/kg body weight·day, the antemortem serum digoxin concentrations (SDC) were 1.1 ± 0.4 ng/mL while the 12-h postmortem concentration was markedly increased (16.3 ± 5.9 ng/mL) (P < 0.01). In rats treated with 3 mg/kg body weight·day, SDC was not changed significantly (11.2 ± 4.8 ng/mL antemortem and 13.3 ± 6 ng/mL postmortem). Postmortem redistribution of digoxin was assessed by injection of ¹²⁵I-labelled digoxin with or without pretreatment with the unlabelled drug. The results indicate that after death passive redistribution of digoxin may take place. When the SDC are within the therapeutic or low toxic range, digoxin may reenter the blood. High antemortem serum concentrations of digoxin may prevent such passive redistribution. Therefore, antemortem digoxin intoxication cannot be reliably inferred on the basis of high postmortem levels of the drug. Digoxin intoxication can be ruled out when postmortem SDC remain within the therapeutic range. The above changes cast doubt on some of the forensic and cardiologic literature, which has in the past been based on incorrect assumptions concerning postmortem behavior of digoxin.