Federal health officials say more research is needed to maximize the use of fentanyl test strips, STAT reports.

In a commentary in this week’s New England Journal of Medicine, health officials including Nora Volkow, the director of the National Institute on Drug Abuse, Food and Drug Administration Commissioner Robert Califf and National Institutes of Health Acting Director Lawrence Tabak write that the United States must ensure that test strips are legal and widely available.

They say the U.S. should work to develop new products and technologies that facilitate drug-checking, a harm-reduction tactic that involves testing a supply of illicit substances to determine its contents. This strategy has become an important component of overdose-prevention efforts as fentanyl has become increasingly widespread, the article notes.

Fentanyl test strips are legal in a large majority of states. The commentary’s authors noted there has been little research on how to maximize the strips’ potential uses. They should be used not just for prevention, but for clinical purposes, they wrote. They called for development of rapid fentanyl testing products that could be used on urine and hair.