Pharmacists play a key role in helping consumers avoid “double dosing” of acetaminophen by reminding them to read Drug Facts labels on over-the-counter (OTC) products so consumers do not inadvertently overdose by using multiple products that contain acetaminophen. Despite these efforts, acetaminophen-related overdose continues to be a leading cause of emergency department visits and hospitalizations as well as drug-induced acute liver failure in the United States.
Therefore, it is important to remember there’s another valuable way in which pharmacists can help consumers reduce their risk of acetaminophen overdose - - by helping patients understand and appreciate the difference between acetaminophen immediate-release (IR) and extended-release (ER) formulations.
Acetaminophen ER has been available OTC in the U.S. since 1994. It is available under the trade names Tylenol® 8 HR Arthritis Pain and Tylenol® 8 HR Muscle Aches & Pain, as well as store brands and generics. The amount of ER acetaminophen sold in the U.S. may be more than pharmacists might estimate. According to an in-house FDA review, sales of single-ingredient OTC acetaminophen ER from U.S. retail stores to consumers represented 4 percent of the total sales of OTC single-ingredient acetaminophen in 2014 and increased to 12 percent in 2017. These data suggest an increase in use of single-ingredient OTC acetaminophen ER in the U.S. and underscore the need for increased awareness of these two similar, but distinctly different formulations.
Tylenol® 8 HR Arthritis Pain and Tylenol® 8 HR Muscle Aches & Pain tablets contain 650 mg of active ingredient per tablet, 325 mg of which is immediately released, with the remaining 325 mg being extended-release. The recommended daily dose is two tablets every eight hours. If taking the maximum daily dose of acetaminophen ER according to the label, a patient may consume up to six tablets, or a total daily dose of 3900 mg. Since the pharmacokinetics of acetaminophen ER differ from that of the IR formulation, patients using the ER drug, who confuse it with the IR product, may exceed the ER product’s recommended dosing and unintentionally absorb toxic amounts of drug.
The FDA asks pharmacists to remember the similarities and differences between acetaminophen IR and ER and to share this information with consumers and other health care professionals as appropriate. Much of what we know about acetaminophen in the U.S. has been gained from pharmacist and healthcare professional reports. FDA reminds you to report adverse events to the MedWatch program. This shared information is key to developing and advancing safety profiles for FDA-approved therapies.
Mary E. Kremzner is the Division Director in FDA’s Center for Drug Evaluation and Research’s Division of Drug Information
1. IRI Multi-Outlet Reporting Solution. 2014-2017. Data extracted November 2018.
2. ACMT Position Statement: Duration of Intravenous Acetylcysteine Therapy Following Acetaminophen Overdose. J Med Toxicol (2017) 13:126-7.