Overview Effect of Guanfacine on the Reversal of Opioid-induced Hyperalgesia (OIH) Status: Active, not recruiting Trial end date: 2021-12-01 Target enrollment: Participant gender: Summary Combination of guanfacine with opioid medication as a standard treatment for chronic pain. Phase: N/A Details Lead Sponsor: Massachusetts General HospitalCollaborators: National Institute on Drug Abuse (NIDA)National Institutes of Health (NIH)Treatments: GuanfacinePolystyrene sulfonic acid