A significant number of adults are at risk of unintentionally overdosing on over-the-counter (OTC) pain medication, according to a new study in the US by Dr. Michael Wolf, from Northwestern University in Chicago, and his colleagues. Their work¹, looking at the prevalence and potential misuse of pain medication containing the active ingredient acetaminophen as well as the likelihood of overdosing, appears online in the Journal of General Internal Medicine², published by Springer.
Many adults in the US regularly use OTC pain medication containing the active ingredient acetaminophen, the most commonly used OTC pain medication in the US. They take it either on its own or in combination with other drugs, which may also contain acetaminophen. The ease of access to OTC drugs presents a challenge to patient safety as many individuals may lack the necessary health literacy skills to self-administer these medicines appropriately. Indeed, individuals make independent decisions that match an OTC product to a self-diagnosed symptom or condition. Worryingly, acetaminophen overdose is the leading cause of acute liver failure.
Wolf and colleagues interviewed 500 adult patients receiving care at outpatient general medicine clinics in Atlanta and Chicago between September 2009 and March 2011. Over half the patients reported some acetaminophen use and 19 percent were 'heavy users' i.e. they had taken it every day, or at least a couple of times a week, during the previous six months.
The researchers tested whether these patients understood the recommended dosage and were able to self-administer OTC acetaminophen appropriately. Firstly, could they work out the proper dosing of a single OTC medication over a 24-hour period? Secondly, what was the risk of patients 'double-dipping', or simultaneously taking two acetaminophen-containing products, and thereby exceeding the recommended dose?
To assess proper dosing, the participants were given five OTC drug bottles and, for each one, were asked to imagine that they took the first dose at time X, and wanted to take the maximum dose of this medicine in one day. They were then asked to show the researcher how many pills and at which times they would need to take them for a full 24-hour day.