By Pat Anson, PNN Editor

Almost every food item you buy in a grocery store has an expiration date. Milk, bread and other perishable items have a “use by” or “sell by” date a few weeks into the future, while a can of beans may have a “best by” date that could be years away.

Should prescriptions for opioids and other controlled substances also have expiration dates? A date when they are no longer valid and can’t be filled?

That’s the premise behind a recent study in JAMA Network Open that looked at over 20 million opioid prescriptions written by U.S. dentists and surgeons in 2019. These were prescriptions primarily intended for short-term acute pain caused by operations or dental procedures.

Over 194,000 of the prescriptions (0.9%) were filled by a pharmacy 30 days or more after they were written – a sign they may have been used for something besides pain from a wisdom tooth extraction.

“Our findings suggest that some patients use opioids from surgeons and dentists for a reason or during a time frame other than intended by the prescriber,” said lead author Kao-Ping Chua, MD, a pediatrician at the University of Michigan Medical School, Ann Arbor.  “These are both forms of prescription opioid misuse, which in turn is a strong risk factor for opioid overdose.”

A misuse rate of about 1% for surgeons and dentists is low, but Chua and his colleagues found the delayed filling of prescriptions was even more common for scripts written by other medical specialists, such as internal medicine doctors (5.6%), family medicine practitioners (7.1%) and nurse practitioners (6.3%).  

Most states already limit the time window between writing and filling a prescription for a controlled Schedule II substance like hydrocodone – usually it’s 120 or 180 days. Eight states allow such prescriptions to be filled up to a year later. A few have no limits at all.  

“It’s perplexing that states would allow controlled substance prescriptions to be filled so long after they are written,” said Chua.

In 2019, Minnesota enacted one of the toughest dispensing laws in the nation, requiring all opioid prescriptions to be filled within 30 days. Delayed dispensing declined significantly in Minnesota soon afterward, before the law was repealed in 2020 out of concern it may have “unintended consequences” for chronic pain patients during the Covid-19 pandemic.  

Chua and his colleagues say more uniform laws should be adopted nationwide that limit the time frame for opioid dispensing only when prescriptions are written for acute pain. They also suggest that prescribers can reduce delayed dispensing themselves by including specific instructions for pharmacists not to dispense opioids after a certain time period.