Digoxin cardiotoxicity in aging anesthetized F344 rats

Evaluation Of The Effectiveness of Dantrolene Sodium against Digoxin-Induced Cardiotoxicity In Adult Rats

BACKGROUND

Digoxin poisoning commonly occurs in people treated with digoxin. It has been suggested that treatment with dantrolene may be a suitable strategy for digoxin-induced cardiotoxicity.

OBJECTIVE

The aim of this study was to evaluate the protective effect of dantrolene on digoxin-induced cardiotoxicity in male rats.

METHODS

This study was approved by the ethics committee of Birjand University of Medical Sciences (Ethical number: IR.BUMS.REC.1400.067). Forty-two Wistar rats weighing between 300- 350 gr were randomly allocated to 7 groups (n=6) as follows:Normal Saline (NS) group, Normal Saline + Ethanol (NS + ETOH) group), Normal Saline + dantrolene 10 mg/kg (NS + Dan 10) group, Digoxin (Dig) group), Digoxin + dantrolene 5 mg/kg (Dig + Dan 5) group),Digoxin + dantrolene 10 mg/kg (Dig + Dan 10) group), Digoxin + dantrolene 20 mg/kg (Dig + Dan 20) group), Dig was injected intravenously at 12 mL / h (0.25 mg / mL). Dan (5, 10 and 20 mg/kg) was injected intravenously at 5-8 min/mL. After 1 hour, blood samples were obtained from the animals' cavernous sinus and each animal's heartremoved. The blood sample was rapidly centrifuged at 2,500 rpm for 10 minutes and the serum was separated for measurement of creatine phosphokinase (CPK), potassium (K), sodium (Na), calcium (Ca), and magnesium (Mg). The samples were stored at -20 oC. The heart samples were fixed in formalin 10% for histopathological evaluation.

RESULTS

K levels slightly increased in the dig group versus the NS group. A significant increase in the K levels was observed in the Dig + Dan 20 group versus the NS group (p < 0.001). dig slightly decreased Ca levels in the treated group versus the NS group. The levels of Ca significantly increased in the Dig + Dan 10 group versus the Dig group (p < 0.05). Histological examination of the heart tissue in the dig group showed cardiomyocyte degeneration, increased edematous intramuscular space associated with hemorrhage, and congestion. Focal inflammatory cell accumulation in the heart tissue was also seen. Cardiomyocytes were clear and arranged in good order in the Dig + Dan 10 group.

CONCLUSION

dantrolene (10 mg/kg) was cardioprotective in a model of digoxin-induced cardiotoxicity, secondary to cardiac remodeling and hyperkalemia. However, further research is necessary to determine dantrolene&#039;s cardioprotective and cardiotoxic doses in animal models.

Pharmacokinetics and pharmacodynamics in toxicology

1. Pharmacokinetics aids interpretation of the dose-response relationship in individual toxicology studies. 2. When used to compare across studies, even in a single species other factors, including variation in pharmacodynamic response, must be taken into account. Variation in pharmacodynamic response becomes more profound when one compares across species. 3. Examples do occur where plasma concentration-response relationships are constant across species, particularly when corrected for unbound drug. These examples should not be taken as support, however, of a general universal principle. 4. Owing to multiple factors such as species differences in receptors, enzymes and ion channels, dose or plasma concentration-response relationships can vary enormously across species. In the light of this, the results of toxicology studies should be viewed as qualitative rather than quantitative. Once sufficient clinical experience is gained the human database is the overriding measure of drug safety.