A new report warns about the risk of medication errors with methotrexate-based drugs, such as Trexall and Rheumatrex, which can result in serious adverse health effects, including death.
In the Institute for Safe Medication Practices (ISMP)’s QuarterWatch (PDF) report release this month, researchers indicate there have been a number of adverse events submitted to the FDA where patients accidentally took the drug daily instead of weekly, resulting in severe injury or death, including at least five patient deaths over an 18-month period.
Methotrexate has been on the market for decades. It was first approved by the FDA in 1953, and is used to treat various forms of cancer, as well as rheumatoid arthritis and psoriasis. However, it is considered highly toxic.
ISMP researchers found that use of methotrexate has increased significantly in recent years. They estimate that the number of patients on the various forms of the drug doubled from just over 500,000 in 2013 to more than 1 million in 2017.
The report notes that problems with methotrexate stem from the wide range of dosages and durations of treatment, leading to patient confusion about when they should take the drug.
“Put simply, a medication error in frequency of taking a tablet can cause severe harm or death,” the researchers warned. “For rheumatoid arthritis and psoriasis, it is taken once weekly. For some oncology indications, much larger doses are administered daily for several days, often with treatment interruptions to allow recovery.”
The report notes that the weekly doses can be even more confusing because they are sometimes given as three smaller divided doses over the course of 12 hours.
Patients who are prescribed the drug weekly and accidentally take it daily face painful and extensive skin damage, suppression of blood cells, liver damage and death. Researchers found that the FDA received five reports of patient deaths specifically due to dosing confusion in the 18 months before June 30, 2019. It also received nine reports of patient hospitalizations due to the same problem.
The researchers found that in six cases, the error was made by the patients, most of whom are older. In eight cases the drug was given to patients incorrectly, either at nursing homes or through pharmacies.
The report also warns that many incidents likely go unreported, and that there were more than 1,800 reports of injuries linked to the medication, which in some cases involved toxic injuries at normal doses.
“In a modern protected society, we should not provide medications that can cause potentially fatal errors affecting up to 1 million people without adequate safety precautions in place,” ISMP researchers warn. “Further, we estimate the methotrexate error risk is getting worse rather than better. As noted, patient use nearly doubled in just four years, exposing many more patients to the risk.”