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Clinical controversies: Have you ever tried viscous lidocaine… : Emergency Medicine News

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viscous lidocaine, medicated, gastrointestinal

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One of my professors of pharmacology in medical school often joked, “Doctors would think twice about giving some questionable drugs if they took them themselves.” There is no better example of this than viscous lidocaine. It may be one of the most nasty drugs ever invented.

Ask the nurses. Many have tasted this sour slime which tastes like stale lemonade with the consistency of runny syrup. Patients agree that it’s horrible. Indeed, patient satisfaction after receiving a GI cocktail is lower when lidocaine is administered. (Acad Emergency Med. 2020;27[9]:905; https://bit.ly/3nq0teM.)

It’s not just the taste. Lidocaine does not add anything to the success of the GI cocktail and you should not give it regularly.

Dyspepsia is a symptom frequently encountered in the emergency room. Classically, it is a mixture of epigastric pain, nausea and bloating. Dyspeptic symptoms are also frequently described as abdominal discomfort relieved by food or antacids, worse at night or while lying down, or associated with a previous diagnosis of peptic ulcer disease or gastroesophageal reflux disease. Emergency physicians routinely administer gastrointestinal cocktails to patients to relieve symptoms.

What is fascinating is the variety of content in these cocktails. Many clinicians have their own favorite blends to give to patients. Some contain antihistamines; others contain simethicone. Liquid combinations of antacids containing calcium carbonate and magnesium hydroxide (Mylanta) or aluminum hydroxide, magnesium hydroxide and simethicone (Maalox) are commonly given. The Donnatal elixir contains phenobarbital, hyoscyamine, atropine and scopolamine. (UpToDate. Nov. 29, 2001; https://bit.ly/3GAfaEC.) Sounds like an M&M case waiting to happen.

Nail in the coffin

Viscous lidocaine has been most studied with Mylanta and Maalox. One of the reasons it became popular was an early randomized controlled trial from 1990 with 34 adult patients that used a visual analog pain scale to compare pain responses after giving 30ml of antacid (Mylanta) with or without 15 ml of viscous lidocaine. They found that lidocaine reduced pain scores compared to antacid alone, but the study did not address any limitations. (UpToDate. Nov. 29, 2001; https://bit.ly/3GAfaEC.)

These positive results, however, have not been replicated since this initial study. Two other randomized controlled trials have been performed (one with 82 patients, another with 113), and neither found that the addition of viscous lidocaine favorably reduced pain scores compared to antacid alone. (J Med Urgent. 2004;27[1]:7; J Med Urgent. 2003;25[3]:239.)

The nail in the coffin came in 2020 when another randomized controlled trial found no difference in pain scores. Patients also did not like the taste of lidocaine even 60 minutes after administration. (Acad Emergency Med. 2020;27[9]:905; https://bit.ly/3nq0teM.)

The literature, although modest evidence from small studies, demonstrates that lidocaine does not reduce patients’ symptoms. And most patients (and staff) think it tastes awful. Next time you’re considering giving it away, try it yourself first.

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Dr. Briggsis an assistant professor of emergency medicine at the University of South Alabama in Mobile. He is the founder, podcast co-host and editor of EM Board Bombs (https://www.emboardbombs.com), a cross-platform educational tool designed to prepare for counseling and focus on what you need to know to practice emergency medicine. Follow him on Twitter@blakebriggsmd.