An experimental drug that relieves pain like morphine but is not addictive showed promise in a study of mice, the Los Angeles Times reports.

Stanford University researchers gave one group of mice the compound, called PZM21. A second group was given morphine. Both groups of mice were placed on a hot surface. PZM21 offered almost as much pain relief as morphine, and lasted for up to three hours—substantially longer than morphine, the researchers report in the journal Nature.

Mice given PZM21 were no more likely to return to a place where they got the drug than to a similar chamber that offered a saline solution. This indicates the mice did not find the compound addictive, the researchers noted.