University of Iowa researchers in the Carver College of Medicine discovered a commonly used drug could treat opioid use disorder, a chronic relapsing condition marked by opioid addiction.
Opioids are a type of drug that relieves pain but can also be highly addictive, according to the National Institute on Drug Abuse.
The study was led by John Wemmie, a psychiatrist and professor at the UI, and used acetazolamide, a drug often sold under the brand name Diamox and prescribed for health problems such as glaucoma and altitude sickness.
The study found that mice self-administered the opioids twice as much as those who did receive the drug.
According to the Johnson County Medical Examiner’s latest annual report published July 2025, 17 residents of Johnson County died from opioid overdose in 2024, seven more people than the year before. The county has yet to publicize opioid deaths from 2025.
Wemmie said existing medications for opioid abuse, such as methadone and buprenorphine, do not solve the long-term relapse risk of drug abuse.
Wemmie said these drugs replace the effects of the opioid receptor someone would feel while taking opioids, while medications like naltrexone block the opioid receptor entirely, significantly reducing the effects of the opioids.
Wemmie said neither methods solve the root problem of drug addiction.
“There’s a thing called incubation craving that if you stop something, the longer you’re abstinent from it, the drive to get it increases,” Wemmie said. “There’s something about having the drug and then not having it, and the desire to have it again grows. That’s what we don’t have a treatment for.”
Wemmie’s team found in 2023 that the enzyme known as carbonic anhydrase plays a role in the brain’s addiction cycle. Wemmie said his team hypothesized that since acetazolamide blocked all variants of carbonic anhydrase, it would, in theory, block the enzyme, helping to reduce opioid craving in mice’s brains.
Wemmie said the team allowed mice to give themselves oxycodone, a highly addictive opioid medication, six hours a day for 10 days, during which the mice would self-administer the drug by pressing a lever.
The team then took away the drug for a month, allowing the mice’s brains to either forget the opioid lever association or increase their cravings. The mice who received acetazolamide pressed the lever half as many times as before because the enzyme had been successfully blocked.
Wemmie’s team found similar trends in subsequent tests with cocaine.
“We’re seeing some very similar things with cocaine,” he said. “It looks like those sorts of mechanisms are generalizing across different types of drugs of abuse. We would expect that, to some degree, it might apply to other drugs of abuse as well.”
Subhash Gupta, a postdoctoral scholar in Wemmie’s lab, said mice’s brain patterns throughout the study showed that acetazolamide showed no harmful effects on synaptic strength, or the strength of communication between the brain’s neurons.
Gupta said the finding suggests that acetazolamide shouldn’t interfere with people’s learning and memory. Gupta said acetazolamide should only dampen the activity in brain pathways that call back to previous opioid use and link the drug to pleasure.
Wemmie said the team still needs to perform subsequent testing and continue to understand acetazolamide’s correlation with opioid withdrawal better before they can move on to human trials.
Gupta said one benefit of acetazolamide is the fact that it is already widely used in similar doses for humans in conditions outside of opioid abuse, in theory making human trials safer.
Rebecca Taugher, a postdoctoral fellow in Wemmie’s lab, was involved in the behavioral side of the mice within the study.
Taugher said the self-administered method allows the mice to press a lever when they want the opioid, a mechanism that padded the study with realism because self-administering is more akin to people seeking drugs rather than the research team administering opioids outside of a natural desire.
“At this point, the work has just been done in mice,” she said. “Before we can really know the clinical impact, the drug will have to be tested in humans. But certainly these results are exciting for the possibility that it may be helpful.”