Treatment of digoxin intoxication in a renal failure patient with digoxin-specific antibody fragments and plasmapheresis

Plasma exchange for the management of digoxin toxicity in an individual with an acute kidney injury: A case report

Digoxin toxicity can be life-threatening. Digoxin-specific antibody (DSA) fragments are used in severe digoxin toxicity, binding to serum-free digoxin and enabling increased renal excretion. In severe renal impairment, clearance of these complexes is prolonged, leading to rebound toxicity. Digoxin and DSA complexes are not dialysable. We present a case of a gentleman with severe digoxin toxicity and acute kidney injury (AKI). Despite receiving DSA doses, his digoxin levels rebounded and symptoms persisted. Based on published case reports, plasma exchange (PEX) after further dosing was arranged. PEX facilitated the removal of digoxin-DSA complexes, bypassing renal excretion. During PEX, clinical signs improved and were sustained. He did not require further dialysis or PEX, renal function recovered and he was discharged. This case highlights challenges in the management of severe digoxin toxicity in patients with a concurrent AKI. The use of PEX enabled digoxin-DSA complex removal and should be considered in these circumstances.

Dialysis and Extracorporeal Therapies for Enhanced Elimination of Toxic Ingestions and Poisoning

Poisoning and toxic ingestions cause significant morbidity and mortality worldwide. Extracorporeal therapies such as dialysis, haemoperfusion and plasma exchange are selectively applied to patients with severe intoxications unresponsive to standard interventions and can be lifesaving. Extracorporeal therapies are a complex but fundamental aspect of the practice of nephrology. Without high-quality evidence to guide implementation, an understanding of toxicokinetics and the physiochemical principles of the enhanced elimination techniques is especially important. This review provides a comphrensive, user-friendly outline of the application of extracorporeal therapy in the poisoned patient.

Drug Dosing in Patients Undergoing Therapeutic Plasma Exchange

Therapeutic plasma exchange (TPE) is an extracorporeal process in which a large volume of whole blood is taken from the patient's vein. Plasma is then separated from the other cellular components of the blood and discarded while the remaining blood components may then be returned to the patient. Replacement fluids such as albumin or fresh-frozen plasma may or may not be used. TPE has been used clinically for the removal of pathologic targets in the plasma in a variety of conditions, such as pathogenic antibodies in autoimmune disorders. TPE is becoming more common in the neurointensive care space as autoimmunity has been shown to play an etiological role in many acute neurological disorders. It is important to note that not only does TPE removes pathologic elements from the plasma, but may also remove drugs, which may be an intended or unintended consequence. The objective of the current review is to provide an up-to-date summary of the available evidence pertaining to drug removal via TPE and provide relevant clinical suggestions where applicable. This review also aims to provide an easy-to-follow clinical tool in order to determine the possibility of a drug removal via TPE given the procedure-specific and pharmacokinetic drug properties.

Digoxin-specific Fab and therapeutic plasma exchange for digitalis intoxication and renal failure

Treatment of chronic digitalis intoxication includes suspension of drug intake, which may be sufficient in case of mild manifestations, and supportive measures. Severe bradycardia requires the administration of atropine or isoproterenol; placement of a temporary pacemaker may be required in case of absent response to pharmacological therapy. Severe and life-threatening manifestations should be treated with digoxin-specific fragment antigen binding antibodies (Fab). Therapeutic plasma exchange has been suggested, in addition to Fab therapy, to maximize the clearance of Fab-digoxin complexes in patients with renal failure. To date, few case reports have described the use of such a therapeutic approach; currently, extracorporeal methods are not recommended as part of the treatment of digitalis intoxication, and stronger evidence is required to establish their benefit.

Therapeutic Plasma Exchange and Its Impact on Drug Levels: An ACLPS Critical Review

OBJECTIVES

To examine and summarize the current literature on the effects of therapeutic plasma exchange on medication levels.

METHODS

Literature review was performed via searches of the Cochrane Database and PubMed-MEDLINE (1996 to August 2016) looking for all case reports, case series, and human randomized controlled trials involving therapeutic plasma exchange (TPE)-associated drug removal.

RESULTS

Approximately 60 peer-reviewed articles were identified with the majority being case reports; no randomized controlled trials were identified. These reports and the authors' own experiences were used to derive practical guidance regarding the effect of TPE on circulating drug levels.

CONCLUSIONS

There were several limitations with existing studies, many of which relate to procedural and/or clinical properties of patients undergoing TPE. As such, additional studies are needed before definitive guidelines can be established. There is clear need for development of consensus and additional investigations in this domain.

Recrudescent digoxin toxicity treated with plasma exchange: a case report and review of literature

A 53-year-old woman presented with digitalis toxicity caused by acute overdose that manifested as atrial tachycardia with block, sinus pauses, and competing AV junctional rhythm with atrial fibrillation. Patient admitted to overdosing with digoxin 15-20 h before presentation with intent to commit suicide. Serum digoxin level was 35.6 ng/ml and renal function was normal. Patient was treated with 1,040 mg of digoxin-specific antibody Fab fragment with prompt resolution of arrhythmias and restoration of sinus rhythm. Four hours after digoxin antibody administration, serum digoxin level declined to 0.2 ng/ml. Eighteen hours after treatment with Fab fragment, patient developed premature ventricular complexes, atrial tachycardia with and without atrioventricular block, and non-sustained ventricular tachycardia followed by ventricular fibrillation from which she was successfully resuscitated. Electrocardiogram showed no evidence of acute myocardial infarction, and emergent coronary angiogram did not reveal significant coronary artery disease. Repeat digoxin level was 20.4 ng/ml. A diagnosis of recrudescent digoxin toxicity was made and the patient was treated with one session of plasma exchange with resolution of arrhythmias. Immediately after plasma exchange, digoxin level decreased to 10.4 ng/ml, and after 10 h, the level further decreased to 6.6 ng/ml. The following day, digoxin level had decreased to 2.9 ng/ml. Our experience with this case would suggest that plasma exchange should be considered as a treatment modality for recrudescent digoxin toxicity.

The role of therapeutic plasma exchange in poisonings and intoxications

Poisonings, intoxications, and drug overdoses are common occurrences and rapid lowering of the toxin level is a cornerstone of all effective therapies. Therapeutic plasma exchange (TPE) has several unique characteristics that allow it to be a potentially effective therapy in rapidly achieving this goal. Specifically, TPE allows for the removal of large molecular weight, protein-bound molecules that have a small volume of distribution. Due to the nature of poisonings, intoxications, and drug overdoses, no randomized controlled trials studying the efficacy of TPE in these situations exist. Thus, careful interpretation and analysis of case reports and series are required to assess the potential efficacy of this therapy. Recent data suggest that TPE may also be effective in the therapy of patients receiving biologic treatments who develop life-threatening complications due to therapy.

Medications in patients treated with therapeutic plasma exchange: prescription dosage, timing, and drug overdose

Therapeutic plasma exchange (TPE) is an extracorporeal process commonly used in clinical medicine for the treatment of a variety of neurological, renal, hematological, dermatological, and other diseases. Inherent to the procedure, patients' plasma removal may lead to the extraction of drugs they are concurrently receiving. This review discusses the published literature assessing TPE's influence on different drug classes' disposition and, when applicable, sets forth management recommendations in cases where the drugs are used at the usual doses and in cases of drug overdose.

Drug removal by plasmapheresis: an evidence-based review

Contrary to the literature about drug removal during hemodialysis, data regarding drug removal during plasmapheresis are sparse. Over the last 40 years, approximately 70 publications-mostly case reports of overdoses-have described the effects of plasmapheresis on pharmaceutical agents. Important issues are drug extraction during plasma exchange with chemotherapy, as well as drug classes such as antiinfectives, anticoagulants, antiepileptics, cardiovascular agents, and immunosuppressants. Other considerations are the merits and pitfalls of the different methods used in published reports and recommendations for future pharmacokinetic studies in this field.

Digoxin poisoning and anuric acute renal failure: efficiency of the treatment associating digoxin-specific antibodies (Fab) and plasma exchanges

Digoxin-specific antibodies (Fab) are currently the treatment of choice for digoxin intoxication. These fragments bind to digoxin, leading to Fab-digoxin complexes, and promote the release of receptor-bound digoxin. These complexes are renally excreted. In the case of anuria, they could be dissociated and lead to renewed intoxication. In this case plasma exchanges are proposed. We report the case of an anuric patient with digoxin intoxication, treated with a Fab injection, followed by a plasma exchange 16 hours later, a second Fab injection was given followed by two plasma exchanges, 38 and 86 hours later. The disappearance of cardiac abnormalities showed the efficiency of the Fab, the drop in serum digoxin concentration and the high digoxin concentration in the exchanged plasma indicate effective elimination. The association of Fab and plasma exchanges could be proposed in the case of digoxin intoxication in the anuric patient.

Plasma exchange for the removal of digoxin-specific antibody fragments in renal failure: timing is important for maximizing clearance

Life-threatening digoxin toxicity may be effectively treated with digoxin-specific antibody fragments (Fab). However, in end-stage renal disease, the digoxin-Fab complexes persist in the circulation and dissociate, potentially resulting in rebounding free digoxin levels and the recurrence of symptomatic toxicity. To prevent this rebound phenomenon, plasma exchange (PE) has been implemented for the removal of the digoxin-Fab complexes in renal failure. However, there is only one case report describing its use in this setting. To better determine the optimal timing of PE after Fab administration, we performed two PE treatments (each preceded by Fab) in a patient with acute renal failure and acute digoxin poisoning. The admission serum digoxin level was 21 ng/mL. The timing of the PE treatments relative to Fab dosing was as follows: the first PE was performed 26 hours post-Fab, and the second PE was performed 2.5 hours post-Fab. The plasma ultrafiltrate digoxin concentration was 2.5-fold greater when PE was performed 2.5 hours versus 26 hours after Fab administration (19.9 versus 8.1 ng/mL). The combined total amount of digoxin removed in the ultrafiltrate plasma was minimal (0.13 mg), less than 1% of the total amount of ingested drug. We conclude that the optimal timing of PE is within the first 3 hours after Fab administration. Although PE is efficacious for removing digoxin-Fab complexes, thus preventing rebound digoxin toxicity, it is not efficacious for improving total digoxin clearance because of the large apparent volume of distribution of digoxin (5 to 8 L/kg).

Poisoning and drug overdose

Poisoning is a common cause for intensive care unit admission for both children and adults, and most poisoning victims are effectively treated using standard decontamination measures and supportive care. For a small number of poisons, acceleration of toxin removal with hemodialysis or hemofiltration is indicated. Similarly, specific antidotes are indicated in a few selected circumstances. Rarely, patients may benefit from more aggressive supportive techniques such as cardiopulmonary bypass.

Digoxin Immune Fab Administration following an Unexplained Increase in Serum Digoxin Concentration

Objective:

To report a case of digoxin immune Fab (DIF) administration following an unexplained increase in serum digoxin concentration in an asymptomatic patient with chronic renal failure.

Case Summary:

A 70-year-old man presented to the hospital with congestive heart failure, atrial fibrillation, chronic renal failure, and suspected digoxin toxicity. By day 3, he developed a more stable cardiac rhythm with nodal beats. His last known digoxin dose was 12 hours prior to admission. No explanation for an elevated serum digoxin concentration 48 hours after admission could be found. Despite absence of other signs of digoxin toxicity, DIF 80 mg iv was administered, and was immediately followed by 40 mg.

Discussion:

This case illustrates that elevated digoxin concentrations may be observed in patients with renal failure. These may not be true high concentrations because of the following potential factors: (1) the presence of digoxin-like factors, (2) increased biotransformation of digoxin, and (3) accumulation of metabolites that interfere with the assay. Digoxin metabolites are known to cross-react with the antibodies in commonly used digoxin immunoassays, and may be inappropriately interpreted to signal digoxin toxicity. Both the accuracy and reliability of digoxin immunoassay techniques have been questioned or challenged over the years. It is difficult to determine whether a reported toxic serum digoxin concentration represents the true concentration or cross-reactivity between digoxin metabolites and antibodies used in most digoxin immunoassays.

Data Sources:

Data collection sources included retrospective review of patient medical records, personal contact with one of the physicians involved in rendering patient care for interpretation of the electrocardiogram changes, clinical symptoms and rationale for DIF administration, and contact with the immunoassay technologist, who indicated that the fluorescence polarization immunoassay technique was used for analysis of digoxin concentrations. The medical literature then was reviewed.

Conclusions:

DIF should be reserved for use in symptomatic patients. Elevated digoxin concentrations must be evaluated for various factors that can cause falsely elevated values. Clinical signs and symptoms are critical in making the decision to use Fab. Antidotal measures should be based on correlation of patient symptoms with serum digoxin concentrations.

Digitalis toxicity. Using immunotherapy when supportive care isn't enough

Significant digitalis toxicity, although uncommon, is a medical emergency. Recognition of the problem and good supportive care (eg, administration of activated charcoal and binding resins, correction of potassium levels, restoration of heart rhythm) are the cornerstones of treatment. If indicated, immunotherapy with digoxin immune Fab (Digibind) is a valuable and effective tool.