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Dofetilide is a class III antiarrhythmic agent primarily used to convert atrial fibrillation or atrial flutter to normal sinus rhythm and maintain sinus rhythm in patients with highly symptomatic atrial fibrillation or atrial flutter lasting longer than a week. This activity reviews the indications, mechanism of action, and contraindications of dofetilide to enhance clinical decision-making for arrhythmic conditions. Other key topics include the drug’s adverse event profile, toxicity, dosing considerations, monitoring requirements, and potential drug interactions. The role of the interprofessional healthcare team in managing dofetilide therapy is highlighted, emphasizing collaboration during acute and chronic arrhythmic care. By addressing these areas, this activity supports healthcare professionals in optimizing treatment strategies to improve patient outcomes and elevate care standards for those requiring dofetilide therapy. Objectives: Evaluate the mechanism of action of dofetilide. Identify the FDA-approved indications and off-label uses for dofetilide therapy. Assess the potential adverse reactions associated with dofetilide administration. Implement effective collaboration and communication among interprofessional team members to improve outcomes and treatment efficacy for patients who might benefit from dofetilide therapy. Access free multiple choice questions on this topic.

Signs and Symptoms of Overdose All class III (potassium channel blockers) antiarrhythmic drugs are proarrhythmic. Therefore, physicians should take extreme care when prescribing dofetilide to patients. Toxic manifestations are usually an extension of pharmacological activity (eg, torsade de pointes). Oral dofetilide doses of 500 μg twice daily have correlations with an increased risk of developing torsades de pointed. There is a report of sudden death; a patient received 2 500 μg dofetilide doses 1 hour apart and developed ventricular fibrillation and cardiac arrest 2 hours after the second dose.[30] During a clinical study, one subject ingested 28 500 μg capsules and received treatment with gastric lavage within 30 minutes of exposure, with reports of no adverse effects. The most likely adverse effect of overdose is the excessive lengthening of the QT interval. A published article by the American College of Medical Toxicology (ACMT) reviewed 23 cases of supratherapeutic dofetilide exposure. Most cases involved older adults (median age 70). The clinical effects of small overdoses were generally minimal, with no significant bradycardia or hypotension. The QTc interval was mildly prolonged (median 460 ms), and electrolyte levels remained within normal limits. One patient who intentionally overdosed on 90 times the usual dose experienced nonsustained ventricular tachycardia and premature ventricular contractions. Management of Overdose

All class III (potassium channel blockers) antiarrhythmic drugs are proarrhythmic. Therefore, physicians should take extreme care when prescribing dofetilide to patients. Toxic manifestations are usually an extension of pharmacological activity (eg, torsade de pointes). Oral dofetilide doses of 500 μg twice daily have correlations with an increased risk of developing torsades de pointed. There is a report of sudden death; a patient received 2 500 μg dofetilide doses 1 hour apart and developed ventricular fibrillation and cardiac arrest 2 hours after the second dose.[30] During a clinical study, one subject ingested 28 500 μg capsules and received treatment with gastric lavage within 30 minutes of exposure, with reports of no adverse effects. The most likely adverse effect of overdose is the excessive lengthening of the QT interval. A published article by the American College of Medical Toxicology (ACMT) reviewed 23 cases of supratherapeutic dofetilide exposure. Most cases involved older adults (median age 70). The clinical effects of small overdoses were generally minimal, with no significant bradycardia or hypotension. The QTc interval was mildly prolonged (median 460 ms), and electrolyte levels remained within normal limits. One patient who intentionally overdosed on 90 times the usual dose experienced nonsustained ventricular tachycardia and premature ventricular contractions. Management of Overdose There is no antidote for dofetilide; treatment of dofetilide overdose is supportive and symptomatic. The management of small overdoses typically involves home observation or brief medical monitoring without requiring invasive interventions. A few patients were treated with magnesium and potassium supplementation. The patient with a large overdose (90 times the usual dose) received magnesium sulfate and potassium chloride and fully recovered. The article highlights that small overdoses are usually manageable with supportive care, while more significant overdoses may necessitate intensive monitoring and treatment.[31] Cardiac monitoring should be initiated with ECG. A charcoal slurry given within the first 15 minutes of administration is beneficial. Pharmacological management of dofetilide overdose and torsades de pointes may include electrolyte correction, isoproterenol, with or without cardiac pacing, and magnesium sulfate; β-blockers have also been used. Recommendations

There is no antidote for dofetilide; treatment of dofetilide overdose is supportive and symptomatic. The management of small overdoses typically involves home observation or brief medical monitoring without requiring invasive interventions. A few patients were treated with magnesium and potassium supplementation. The patient with a large overdose (90 times the usual dose) received magnesium sulfate and potassium chloride and fully recovered. The article highlights that small overdoses are usually manageable with supportive care, while more significant overdoses may necessitate intensive monitoring and treatment.[31] Cardiac monitoring should be initiated with ECG. A charcoal slurry given within the first 15 minutes of administration is beneficial. Pharmacological management of dofetilide overdose and torsades de pointes may include electrolyte correction, isoproterenol, with or without cardiac pacing, and magnesium sulfate; β-blockers have also been used. Recommendations The suggested approach by (Crosby J et al, 2021) for managing acquired QT prolongation with torsades de pointes (TdP) begins with administering 2 grams of intravenous magnesium, which reduces calcium influx into the cytoplasm from the sarcoplasmic reticulum. This influx, triggered by L-type calcium channels, contributes to early afterdepolarizations and triggered activity responsible for self-limiting TdP episodes. If the symptoms persist, lidocaine is used, as it blocks late sodium currents, significantly shortening the QT interval in cases caused by hERG potassium-channel blockers like dofetilide. In cases where the patient becomes hemodynamically unstable or progresses to ventricular fibrillation, immediate defibrillation is performed following Advanced Cardiac Life Support guidelines. For patients who remain stable but continue to experience self-limiting TdP, isoproterenol is administered to raise the heart rate and reduce the QT interval. If the heart rate is below 85 beats per minute, overdrive pacing is initiated to counteract the patient's intrinsic ventricular ectopy, typically 90 to 110 beats per minute. Transvenous pacing may be required to maintain this heart rate in some instances. Isoproterenol acts as a pharmacological pacemaker, supporting rate control and helping to reduce the QT interval.[30]

Dofetilide is a class III antiarrhythmic agent usually prescribed by a cardiologist. However, patients with arrhythmias are often followed and monitored by their primary care provider, cardiac nurse, and internist. Healthcare providers who care for patients with arrhythmias must be aware of the adverse effects of these agents. This knowledge extends to the nursing staff, who will administer the drug and most likely perform the initial observation of any adverse effects or drug interactions. Pharmacists should verify dosing and perform thorough medication reconciliation to rule out drug interactions and ensure proper dosing, preventing potentially severe adverse effects. They should communicate concerns to the physician or nursing staff to initiate appropriate corrective action. All class III (potassium channel blockers) antiarrhythmic drugs are proarrhythmic as well. Therefore, extreme care should be necessary for clinicians when prescribing dofetilide. All healthcare professionals, including the cardiac nurse and pharmacist, should consult a cardiologist regarding potential dosing or administration schedule changes.[32] Emergency medicine physicians should rapidly stabilize the patient in case of overdose presenting with torsades de pointes. For refractory arrhythmia, cardiology should be consulted. If the ingestion is intentional, psychiatry consultation is required. As demonstrated above, An interprofessional team approach and communication among clinicians are crucial to decreasing potential adverse effects and improving patient outcomes related to dofetilide therapy.