A case of near-fatal flecainide overdose in a neonate successfully treated with sodium bicarbonate

Case report: Use of therapeutic drug monitoring and pharmacogenetic testing as opportunities to individualize care in a case of flecainide toxicity after fetal supraventricular tachycardia

Flecainide is a class IC antiarrhythmic utilized in prophylaxis of refractory paroxysmal supraventricular tachycardias in pediatric populations. Despite being a highly effective agent, its narrow therapeutic index increases the risk of toxicity and proarrhythmic events, including wide-complex tachycardia. In the absence of direct plasma sampling in the fetus to quantitate flecainide systemic concentrations, clinicians typically make drug dosing decisions from maternal plasma concentrations and QRS duration on maternal ECGs. There remains a paucity of standard guidelines and data to inform the timing and frequency of the aforementioned test in pregnancy and timing of flecainide discontinuation prior to childbirth. Flecainide primarily undergoes metabolism via cytochrome P450 (CYP). Given the variance of CYP-mediated metabolism at the level of the individual patient, pharmacogenomics can be considered in patients who present with flecainide toxicity to determine the maternal vs. fetal factors as an etiology for the event. Finally, pharmacogenetic testing can be utilized as an adjunct to guide flecainide dosing decisions, but must be done with caution in neonates <2 weeks of age. This case report highlights utilization of pharmacogenomic testing and therapeutic drug monitoring as adjuncts to guide therapy for a newborn with refractory supraventricular tachycardia, who experienced flecainide toxicity immediately post-partum and was trialed unsuccessfully on multiple alternative antiarrhythmics without rhythm control.

Flecainide toxicity: ECG changes associated with supratherapeutic levels in milk-fed infants

Flecainide is a class 1C antiarrhythmic and is highly effective for treating a wide range of arrhythmias. It is not licensed for children under the age of 12 years, but has been used safely for years in young children, particularly when first-line agents are not effective. Although toxicity does occur in both adult and paediatric populations, there have been very few reported instances of flecainide toxicity in neonates and children. Supratherapeutic levels of flecainide manifests on ECG with prolongation of the PR interval, QRS duration and QT, and can lead to life-threatening arrhythmias. In milk-fed infants receiving flecainide, regular feeding patterns are paramount to achieve a steady therapeutic state, as milk and dairy products are known to reduce the absorption of flecainide. This case series details four milk-fed infants admitted with ECG changes secondary to flecainide toxicity.

Creating Data Standards to Support the Electronic Transmission of Compounded Nonsterile Preparations (CNSPs): Perspectives of a United States Pharmacopeia Expert Panel

The perspectives of the Compounded Drug Preparation Information Exchange Expert Panel of the United States Pharmacopeia (CDPIE-EP) on the urgent need to create and maintain data standards to support the electronic transmission of an interoperable dataset for compounded nonsterile preparations (CNSPs) for children and the elderly is presented. The CDPIE-EP encourages all stakeholders associated with the generation, transmission, and preparation of CNSPs, including standards-setting and informatics organizations, to discern the critical importance of accurate transmission of prescription to dispensing the final product and an urgent need to create and adopt a seamless, transparent, interoperable, digitally integrated prescribing and dispensing system benefiting of all patients that need CNSPs, especially for children with special healthcare needs and medical complexity (CSHCN-CMC) and for adults with swallowing difficulties. Lay summary: Current electronic prescription processing standards do not permit the complete transmission of compounded nonsterile preparations (CNSPs) from a prescriber to dispenser. This lack creates multiple opportunities for medication errors, especially at transitions of care for children with medical complexity and adults that cannot swallow tablets and capsules. The United States Pharmacopeia Expert Panel on Compounded Drug Preparation Information Exchange aims to reduce this source of error by creating ways and means for CNSPs to be transmitted within computer systems across the continuum of care. Twitter: Digitizing compounded preparation monographs and NDC-like formulation identifiers in computerized prescription systems will minimize error.

Compounded Nonsterile Preparations and FDA-Approved Commercially Available Liquid Products for Children: A North American Update

The purpose of this work was to evaluate the suitability of recent US Food and Drug Administration (US-FDA)-approved and marketed oral liquid, powder, or granule products for children in North America, to identify the next group of Active Pharmaceutical Ingredients (APIs) that have high potential for development as commercially available FDA-approved finished liquid dosage forms, and to propose lists of compounded nonsterile preparations (CNSPs) that should be developed as commercially available FDA-approved finished liquid dosage forms, as well as those that pharmacists should continue to compound extemporaneously. Through this identification and categorization process, the pharmaceutical industry, government, and professionals are encouraged to continue to work together to improve the likelihood that patients will receive high-quality standardized extemporaneously compounded CNSPs and US-FDA-approved products.

Management of life-threatening flecainide overdose: a case report of an infant

Flecainide overdose is associated with an approximately 10% mortality rate. The drug's slow rate of elimination and high oral bioavailability make successful management extremely challenging. I present the management of a life-threatening flecainide overdose of an infant who had a protracted course due to the exposure to the drug in both the fetal and neonatal periods.

Flecainide Toxicity Secondary to Accidental Overdose: A Pediatric Case Report of Two Brothers

Flecainide is a class 1C antiarrhythmic with a narrow therapeutic window and thereby a high-risk medication for causing acute toxicity. Dysrhythmias secondary to flecainide ingestion are often refractory to antiarrhythmics and cardioversion, and patients commonly require extracorporeal support. We review the successful resuscitation of two brothers aged 2 and 4 who presented two years apart with unstable wide-complex tachyarrhythmia suspicious for severe flecainide toxicity. Each patient received sodium bicarbonate and 20% intravenous lipid emulsion with a full recovery. While extracorporeal support is often required following flecainide ingestion, we present two cases where it was avoided due to aggressive multimodal management with sodium bicarbonate, electrolyte repletion, and 20% intravenous lipid emulsion. In addition, avoidance of agitation-induced tachycardia may be beneficial.

Pilsicainide Intoxication with Neuropsychiatric Symptoms Treated with Continuous Hemodiafiltration

A 72-year-old lady with atrial fibrillation and chronic renal failure was hospitalized due to bradycardic shock with electrocardiographic QRS prolongation. She had experienced limb shaking two days before hospitalization, and additionally developed hallucinations one day before admission. Pilsicainide intoxication was diagnosed from a review of her medications and electrocardiographic findings. Consequently, continuous hemodiafiltration was performed resulting in a resolution of the hallucinations and the QRS prolongation. This is a rare case of psychiatric symptoms caused by pilsicainide intoxication. It is important to know the mode of excretion of a drug and to adjust its dose, so that such drug-related incidents can be avoided.

Complete Heart Block Secondary to Flecainide Toxicity: Is It Time for CYP2D6 Genotype Testing?

Flecainide acetate is a Vaughan-Williams class IC antiarrhythmic drug prescribed for the treatment of supraventricular arrhythmias. It has a narrow therapeutic index and proarrhythmic effects even at therapeutic doses. Flecainide is metabolized by a CYP2D6 enzyme that exhibits polymorphism. In this case report, we present, to our best knowledge, the first case of toxicity contributed by genetic polymorphism in an infant. Our patient with recurrent supraventricular tachycardia was treated with a therapeutic dose of flecainide but developed heart block requiring extracorporeal membrane oxygenation support and subsequent treatment with lipid emulsion therapy. He was found to have supratherapeutic serum flecainide concentration, and gene testing revealed the patient to be an intermediate metabolizer. With this case report, we reinforce the importance of evaluating the CYP2D6 genotype before drug initiation in the neonatal population and recommend regular monitoring of serum flecainide levels and electrocardiograms in these patients.

Rapid Quantitation of Flecainide in Human Plasma for Therapeutic Drug Monitoring Using Liquid Chromatography and Time-of-Flight Mass Spectrometry

BACKGROUND

Measurement of flecainide is useful to optimize dosage and minimize risks of toxicity. Furthermore, there is a need for urgent sample analysis when flecainide is used in transplacental therapy for fetal tachycardia. To this end, we have developed and validated a rapid assay for the measurement of flecainide in human plasma or serum, using a small sample volume (50 µL).

METHODS

After a simple deproteination with zinc sulfate and methanol, prepared samples were injected onto a short (30 mm) analytical column and eluted using a rapid gradient elution. Detection was performed using time-of-flight mass spectrometry. Flecainide was quantified using flecainide-D4 as internal standard, with both compounds extracted from the total ion chromatogram using a ±5 ppm extraction window based on the theoretical m/z values for the protonated ions.

RESULTS

The assay was linear over a putative therapeutic range (100-1500 mcg/L). Between- and within-assay imprecision and accuracy were <4.6% and 94.8%-110.0%, respectively. Matrix effects were minimal and were compensated for by flecainide-D4. There were no effects due to hemolysis or lipemia, and no carryover was apparent. Total analysis time was just 1.2 minutes (72 seconds).

CONCLUSIONS

We have developed and validated a rapid method for the analysis of flecainide. The method is particularly suited for flecainide therapeutic drug monitoring, when analyzing samples from mothers receiving flecainide for the treatment of fetal tachycardia.

Life-Threatening Errors With Flecainide Suspension in Children

Errors with flecainide suspension in children.

Drug-induced cardiac abnormalities in premature infants and neonates

The Cardiac Safety Research Consortium (CSRC) is a transparent, public-private partnership that was established in 2005 as a Critical Path Program and formalized in 2006 under a Memorandum of Understanding between the United States Food and Drug Administration and Duke University. Our continuing goal is to advance paradigms for more efficient regulatory science related to the cardiovascular safety of new therapeutics, both in the United States and globally, particularly where such safety questions add burden to innovative research and development. This White Paper provides a summary of discussions by a cardiovascular committee cosponsored by the CSRC and the US Food and Drug Administration (FDA) that initially met in December 2014, and periodically convened at FDA's White Oak headquarters from March 2015 to September 2016. The committee focused on the lack of information concerning the cardiac effects of medications in the premature infant and neonate population compared with that of the older pediatric and adult populations. Key objectives of this paper are as follows: Provide an overview of human developmental cardiac electrophysiology, as well as the electrophysiology of premature infants and neonates; summarize all published juvenile animal models relevant to drug-induced cardiac toxicity; provide a consolidated source for all reported drug-induced cardiac toxicities by therapeutic area as a resource for neonatologists; present drugs that have a known cardiac effect in an adult population, but no reported toxicity in the premature infant and neonate populations; and summarize what is not currently known about drug-induced cardiac toxicity in premature infants and neonates, and what could be done to address this lack of knowledge. This paper presents the views of the authors and should not be construed to represent the views or policies of the FDA or Health Canada.

When potion becomes poison! A case report of flecainide toxicity

We report a 48-day-old female infant, who developed cardiac conduction abnormalities and seizures secondary to supratherapeutic doses of oral flecainide. Flecainide was started in this infant for treatment of supraventricular tachycardia. The drug was withdrawn with successful normalization of the QRS complex and no further recurrence of seizures. The Naranjo probability score for adverse drug reaction was 8, making the causality “probable.” The case restates an important message that physicians should be aware of the side effects of the drugs that they prescribe, especially of those drugs which have a narrow therapeutic window.

Flecainide toxicity in a preterm neonate with permanent junctional reciprocating tachycardia

We report a case of flecainide toxicity in a premature neonate with permanent junctional reciprocating tachycardia which was managed successfully by reversal of the sodium blockade with intravenous sodium bicarbonate and supportive care. This report highlights the importance of strict supervision and monitoring while administering antiarrhythmic drugs in neonates and prompt institution of appropriate remedial action for treatment when toxicity is suspected.

Patient-Controlled Analgesia Basal Infusion Overdose; Life-threatening Errors with Flecainide Suspension in Children; Medical Product Error-Prevention Efforts Need to be Shared and Harmonized Internationally

These medication errors have occurred in health care facilities at least once. They will happen again—perhaps where you work. Through education and alertness of personnel and procedural safeguards, they can be avoided. You should consider publishing accounts of errors in your newsletters and/or presenting them at your inservice training programs.

Your assistance is required to continue this feature. The reports described here were received through the Institute for Safe Medication Practices (ISMP) Medication Errors Reporting Program. Any reports published by ISMP will be anonymous. Comments are also invited; the writers’ names will be published if desired. ISMP may be contacted at the address shown below.

Errors, close calls, or hazardous conditions may be reported directly to ISMP through the ISMP Web site ( www.ismp.org ), by calling 800-FAIL-SAFE, or via e-mail at ismpinfo@ismp.org . ISMP guarantees the confidentiality and security of the information received and respects reporters’ wishes as to the level of detail included in publications.

Ventricular dysrhythmias associated with poisoning and drug overdose: a 10-year review of statewide poison control center data from California

BACKGROUND

Ventricular dysrhythmias are a serious consequence associated with drug overdose and chemical poisoning. The risk factors for the type of ventricular dysrhythmia and the outcomes by drug class are not well documented.

OBJECTIVE

The aim of this study was to determine the most common drugs and chemicals associated with ventricular dysrhythmias and their outcomes.

METHODS

We reviewed all human exposures reported to a statewide poison control system between 2002 and 2011 that had a documented ventricular dysrhythmia. Cases were differentiated into two groups by type of arrhythmia: (1) ventricular fibrillation and/or tachycardia (VT/VF); and (2) torsade de pointes (TdP).

RESULTS

Among the 300 potential cases identified, 148 cases met the inclusion criteria. Of these, 132 cases (89%) experienced an episode of VT or VF, while the remaining 16 cases (11%) had an episode of TdP. The most commonly involved therapeutic classes of drugs associated with VT/VF were antidepressants (33/132, 25%), stimulants (33/132, 25%), and diphenhydramine (16/132, 12.1%). Those associated with TdP were antidepressants (4/16, 25%), methadone (4/16, 25%), and antiarrhythmics (3/16, 18.75%). Drug exposures with the greatest risk of death in association with VT/VF were antidepressant exposure [odds ratio (OR) 1.71; 95% confidence interval (CI) 0.705-4.181] and antiarrhythmic exposure (OR 1.75; 95% CI 0.304-10.05), but neither association was statistically significant. Drug exposures with a statistically significant risk for TdP included methadone and antiarrhythmic drugs.

CONCLUSIONS

Antidepressants and stimulants were the most common drugs associated with ventricular dysrhythmias. Patients with suspected poisonings by medications with a high risk of ventricular dysrhythmia warrant prompt ECG monitoring.

Sodium acetate as a replacement for sodium bicarbonate in medical toxicology: a review

Sodium bicarbonate is central to the treatment of many poisonings. When it was placed on the FDA drug shortage list in 2012, alternative treatment strategies to specific poisonings were considered. Many hospital pharmacies, poison centers, and medical toxicologists proposed sodium acetate as an adequate alternative, despite a paucity of data to support its use in medical toxicology. The intention of this review is to educate the clinician on the use of sodium acetate and to advise them on the potential adverse events when given in excess. We conducted a literature search focused on the pharmacology of sodium acetate, its use as a buffer in pathologic acidemia and dialysis baths, and potential adverse events associated with excess sodium acetate infusion. It appears safe to replace sodium bicarbonate infusion with sodium acetate on an equimolar basis. The metabolism of acetate, however, is more complex than bicarbonate. Future prospective studies will be needed to confirm the efficacy of sodium acetate in the treatment of the poisoned patient.