Bupropion-Associated QRS Prolongation Unresponsive to Sodium Bicarbonate Therapy

Electrocardiographic Effects of Bupropion Toxicity Suggesting Dysfunction of the Gap Junction or Connexin 43

This is a case of a 20-year-old pregnant female presenting EKG abnormalities associated with an overdose of bupropion. These ECG abnormalities are prolongation of the QRS, prolongation of the corrected QT interval (QTc), right axis deviation, and a terminal R wave. The propagation of electricity through the myocardium is dependent on many factors. It is dependent on the flow of sodium from the extracellular to intracellular space, flow of potassium from intracellular to extracellular space, and ultimately the propagation of the signal at the gap junction by Connexin 43 (Cx-43). We postulate that the ECG abnormalities in this case are secondary to bupropion's effect on the potassium rectifier channels (Kir) and or Cx-43 at the gap junction.

The Timing of Clinical Effects of Bupropion Misuse Via Insufflation Reported to a Regional Poison Center

BACKGROUND

Bupropion is an antidepressant medication with expanding indications including smoking cessation, weight loss, attention-deficit/hyperactivity disorder, seasonal affective disorder, and amphetamine dependence. Despite its increasing popularity among providers, it has a well-known narrow therapeutic window that can lead to delayed onset of symptoms with extended-release formulations and devastating consequences in overdose. We have noticed some patients misusing bupropion via insufflation, which added a layer of complexity with regards to the therapeutic application of the drug. This route of use created difficult decisions regarding clinical monitoring in these patients.

OBJECTIVES

To determine if prolonged observation is required after insufflation of bupropion and to further describe effects from this route of use.

METHODS

This is a retrospective observational study reviewing all the cases of insufflated bupropion use reported to a single poison center without any other coingestants.

RESULTS

The majority (85.7%) of patients had mild or moderate effects, and seizures occurred in 19.6% of cases; and the vast majority of patients were symptomatic by the time of the initial call to the poison center. We did not encounter any delayed effects after this route of use.

CONCLUSIONS

This report describes the clinical effects reported, and the timing of these effects, after insufflation of bupropion.

Clinical effects of intravenous bupropion misuse reported to a regional poison center

Bupropion is an antidepressant medication with expanding indications including smoking cessation, weight loss, attention-deficit/hyperactivity disorder, seasonal affective disorder, and amphetamine dependence. Despite its increasing popularity among providers, it has a well-known narrow therapeutic window which can lead to delayed onset of symptoms with extended-release formulations and devastating consequences in overdose. We have noticed some patients misusing bupropion via intravenous use and had difficulty guiding decisions regarding clinical monitoring in these patients. As this route entirely changes the kinetics of bupropion, this has caused concern within our group. We reviewed all the cases of intravenous bupropion use reported to a single poison center without any other coingestants. The majority (66.7%) of patients had moderate effects and one patient had a seizure. No deaths were reported. All patients were symptomatic by the time of initial call to the poison center if they had any reported symptoms due to bupropion. This case series describes the clinical effects reported, and the timing of these effects, after intravenous bupropion use.

Massive lamotrigine and bupropion overdose resulting in status epilepticus without cardiovascular collapse

An 18 year-old woman presented to an outside hospital with seizure activity after a massive ingestion of lamotrigine, bupropion, trazodone, buspirone, and possibly isoretinoin. Her initial vital signs were remarkable for tachycardia (120 bpm). She was intubated for airway protection. For treatment of status epilepticus, she received a total of 12 mg of IV lorazepam along with a lorazepam infusion titrated to 15 mg/hr, a propofol infusion of unknown dosing, and phenobarbital 650 mg. She was transferred to a receiving hospital. Her initial ECG at the receiving hospital showed a QRS of 117 ms which narrowed with 50 mEq of sodium bicarbonate after approximately 6 hours. She required norepinephrine intermittently for blood pressure support for approximately 2 days. The patient had no dysrhythmias. EEG showed no epileptiform activity from approximately 11 hours–32 hours post ingestion. At the receiving hospital, her serum lamotrigine concentration was 109 mcg/mL (reference 3.0–14.0 mcg/mL) 7 hours after ingestion. Her bupropion concentration was 92 ng/mL (reference 50–100 ng/mL). She was extubated on hospital day 5 and discharged to a psychiatric facility on hospital day 13.

Successful Management of Adolescent Bupropion Overdose with Intravenous Lipid Emulsion Therapy

Bupropion overdose in the pediatric setting poses significant potential for toxicity. We present the case of a 15-year-old female patient presenting with intentional bupropion overdose resulting in generalized tonic-clonic seizures, severe acidosis, vomiting, and tachycardia after ingestion of between 1,650 to 9,000 mg (24-133 mg/kg) of bupropion. The patient was admitted to pediatric intensive care unit (PICU) where toxicity was resolved promptly following administration of intravenous lipid emulsion (ILE) infusion. ILE is a first-line treatment for other forms of toxicity including unintended local anesthetic administration. ILE use is not a first-line treatment in this setting, but this case presents a positive subsequent patient outcome.

A Literature Review of the Use of Sodium Bicarbonate for the Treatment of QRS Widening

Sodium bicarbonate is a well-known antidote for tricyclic antidepressant (TCA) poisoning. It has been used for over half a century to treat toxin-induced sodium channel blockade as evidenced by QRS widening on the electrocardiogram (ECG). The purpose of this review is to describe the literature regarding electrophysiological mechanisms and clinical use of this antidote after poisoning by tricyclic antidepressants and other agents. This article will also address the literature supporting an increased serum sodium concentration, alkalemia, or the combination of both as the responsible mechanism(s) for sodium bicarbonate's antidotal properties. While sodium bicarbonate has been used as a treatment for cardiac sodium channel blockade for multiple other agents including citalopram, cocaine, flecainide, diphenhydramine, propoxyphene, and lamotrigine, it has uncertain efficacy with bupropion, propranolol, and taxine-containing plants.

QRS widening and QT prolongation under bupropion: a unique cardiac electrophysiological profile

QRS widening and QT prolongation are associated with bupropion. The objectives were to elucidate its cardiac electrophysiological properties. Patch-clamp technique was used to assess the I(Kr) -, I(Ks) -, and I(Na) -blocking effects of bupropion. Langendorff retroperfusion technique on isolated guinea-pig hearts was used to evaluate the MAPD(90) -, MAP amplitude-, phase 0 dV/dt-, and ECG-modulating effects of bupropion and of two gap junction intercellular communication inhibitors: glycyrrhetinic acid and heptanol. To evaluate their effects on cardiac intercellular communication, fluorescence recovery after photobleaching (FRAP) technique was used. Bupropion is an I(Kr) blocker. IC(50) was estimated at 34 μm. In contrast, bupropion had hardly any effect on I(Ks) and I(Na) . Bupropion had no significant MAPD(90) -modulating effect. However, as glycyrrhetinic acid and heptanol, bupropion caused important reductions in MAP amplitude and phase 0 dV/dt. A modest but significant QRS-widening effect of bupropion was also observed. FRAP experiments confirmed that bupropion inhibits gap junctional intercellular communication. QT prolongation during bupropion overdosage is due to its I(Kr) -blocking effect. QRS widening with bupropion is not related to cardiac sodium channel block. Bupropion rather mimics the QRS-widening, MAP amplitude- and phase 0 dV/dt -reducing effect of glycyrrhetinic acid and heptanol. Unlike class I anti-arrhythmics, bupropion causes cardiac conduction disturbances by reducing cardiac intercellular coupling.

Drugs and pharmaceuticals: management of intoxication and antidotes

The treatment of patients poisoned with drugs and pharmaceuticals can be quite challenging. Diverse exposure circumstances, varied clinical presentations, unique patient-specific factors, and inconsistent diagnostic and therapeutic infrastructure support, coupled with relatively few definitive antidotes, may complicate evaluation and management. The historical approach to poisoned patients (patient arousal, toxin elimination, and toxin identification) has given way to rigorous attention to the fundamental aspects of basic life support--airway management, oxygenation and ventilation, circulatory competence, thermoregulation, and substrate availability. Selected patients may benefit from methods to alter toxin pharmacokinetics to minimize systemic, target organ, or tissue compartment exposure (either by decreasing absorption or increasing elimination). These may include syrup of ipecac, orogastric lavage, activated single- or multi-dose charcoal, whole bowel irrigation, endoscopy and surgery, urinary alkalinization, saline diuresis, or extracorporeal methods (hemodialysis, charcoal hemoperfusion, continuous venovenous hemofiltration, and exchange transfusion). Pharmaceutical adjuncts and antidotes may be useful in toxicant-induced hyperthermias. In the context of analgesic, anti-inflammatory, anticholinergic, anticonvulsant, antihyperglycemic, antimicrobial, antineoplastic, cardiovascular, opioid, or sedative-hypnotic agents overdose, N-acetylcysteine, physostigmine, L-carnitine, dextrose, octreotide, pyridoxine, dexrazoxane, leucovorin, glucarpidase, atropine, calcium, digoxin-specific antibody fragments, glucagon, high-dose insulin euglycemia therapy, lipid emulsion, magnesium, sodium bicarbonate, naloxone, and flumazenil are specifically reviewed. In summary, patients generally benefit from aggressive support of vital functions, careful history and physical examination, specific laboratory analyses, a thoughtful consideration of the risks and benefits of decontamination and enhanced elimination, and the use of specific antidotes where warranted. Data supporting antidotes effectiveness vary considerably. Clinicians are encouraged to utilize consultation with regional poison centers or those with toxicology training to assist with diagnosis, management, and administration of antidotes, particularly in unfamiliar cases.