Abstract 15735: Acquired Long-QT Syndrome Due to Excessive Loperamide Use

Background: Loperamide is an over-the-counter opioid used primarily to treat diarrhea. Toxicity is known to predispose patients to life-threatening QT-interval prolongation and ventricular dysrhythmias. Case: A 42 year-old man with a past medical history of palpitations, tobacco use disorder, chronic back pain, and opioid use disorder presented to the hospital for syncope. In the preceding days, he experienced three episodes of palpitations followed by dizziness that would cause him to lose consciousness and fall, lasting five seconds each. He noted a longstanding opioid use history for chronic back pain, initially treated with oxycodone at a maximum dose of 600mg daily with transition to heroin for a total of three months. The patient then self-managed his opioid dependence with loperamide five years prior to admission, initially using doses of 200 mg daily, followed by three years of taking 768mg of loperamide daily. In attempts to avoid known electrophysiologic complications, he co-administered vitamin C (12,000-14,000 mg daily), magnesium citrate (1200mg/day), D3 (4000u daily), fish oil, centrum multivitamin 2 pills daily, and zinc. In the Emergency Department, the patient was given was given intravenous calcium, amiodarone, and magnesium for recurrent pulseless ventricular tachycardia, ultimately defibrillated and converted to junctional bradycardia. He was admitted to the cardiac care unit. Left heart catheterization demonstrated nonobstructive coronary artery disease; transthoracic echocardiogram was only notable for ejection fraction of 45%. He was treated with transvenous pacemaker (TVP) placement with pacing at 100bpm. Because of increasing intensity of opioid withdrawal, TVP was removed and isoproterenol infusion was started, while initiating transition to suboxone for maintenance treatment. Conclusion: This is the highest reported dose of loperamide intoxication as a method to self-manage opioid dependence. Despite low addictive potential, loperamide may be used at higher doses for opioid dependence or its euphoric effects. Treatment of loperamide toxicity should be aimed at reducing the risk of cardiotoxicity and managing withdrawal symptoms during detoxification, given its variable half-life.