Management of digoxin therapy using pharmacokinetics in a patient undergoing continuous venovenous hemofiltration

The Impact of Continuous Veno-Venous Hemodiafiltration on the Efficacy of Administration of Prophylactic Doses of Enoxaparin: A Prospective Observational Study

BACKGROUND

Critically ill patients frequently require continuous renal replacement therapy (CRRT). During CRRT, particles up to 10 kDa in size, such as enoxaparin, may be removed. The aim of this study was to determine if patients receiving prophylactic doses of enoxaparin and treated with continuous veno-venous hemodiafiltration (CVVHDF) reach prophylactic values of anti-Xa factor activity.

METHODS

In this observational trial, we compared two groups: 20 patients treated with CVVHDF and 20 patients not treated with CVVHDF. All of them received prophylactic doses of 40 mg of enoxaparin subcutaneously. Anti-Xa factor activity was determined on the third day of receiving a prophylactic dose of enoxaparin. The first blood sample was taken just before the administration of enoxaparin, and other samples were taken 3 h, 6 h, and 9 h after the administration of a prophylactic dose of enoxaparin.

RESULTS

At 3 and 6 h after administration of enoxaparin in both groups, we observed a significant increase in anti-Xa factor activity from baseline, with the peak after 3 h of administration. There were no significant differences in the numbers of patients who had anti-Xa factor activity within the prophylactic range between CVVHDF and control groups.

CONCLUSION

CVVHDF has only a mild effect on the enoxaparin prophylactic effect measured by anti-Xa factor activity. Thus, it seems there is no need to increase the dose of enoxaparin for patients requiring CVVHDF.

Continuous venovenous hemodialysis may be effective in digoxin removal in digoxin toxicity: A case report

Digoxin is a cardiac glycoside that is used for the treatment of heart failure and atrial fibrillation. Besides its careful close follow-up, toxicity affects nearly 1% of congestive heart failure patients. Cessation of the drug, appropriate electrolyte and rhythm control and digoxin-Fab antibody are the mainstay for toxicity treatment in these patients. As known, hemodialysis and peritoneal dialysis are not effective by the means of digoxin removal. We present a 66-year-old patient who admitted to hospital with digoxin toxicity and severe acute kidney injury. The patient was treated with continuous venovenous hemodialysis because of her hypervolemia, hyperkalemia, cardiac instability, and the thought of probable decrease in digoxin levels concerning the continuous nature of solute clearance. Without the treatment using digoxin-specific Fab antibodies, the patient's digoxin level was decreased successfully with continuous venovenous hemodialysis. In conclusion, continuous venovenous hemodialysis may be a treatment option in digoxin toxicity especially those who suffer from severe renal dysfunction and cannot access digoxin antidote.

Utility of Physiologically Based Pharmacokinetic Modeling in Point-of-Care Decisions: An Example Using Digoxin Dosing in Continuous Venovenous Hemodiafiltration

We describe the case of a patient on continuous venovenous hemodiafiltration with atrial fibrillation with rapid ventricular response and hypotension requiring vasopressor use, which warranted digoxin therapy. In the absence of guidelines specifying appropriate digoxin dosing in patients undergoing continuous venovenous hemodiafiltration, anecdotal evidence-guided digoxin dosing was performed for this patient using plasma digoxin concentration-based therapeutic drug monitoring. We use this case to demonstrate the potential role of physiologically based pharmacokinetic modeling in assisting therapeutic decision making.