(HealthDay News) – Heroin-addicted patients treated with methadone or buprenorphine have a heightened sensitivity to pain, and the hyperalgesia does not change over the course of treatment.
Peggy Compton, RN, PhD, from the University of California in Los Angeles, and colleagues compared pain responses to cold-pressor and electrical stimulation for 11 treatment-seeking heroin-dependent adults allocated to methadone, 64 allocated to buprenorphine, and 21 drug-free controls. Participants allocated to methadone and buprenorphine were evaluated at baseline (treatment entry), medication stabilization (4–8 weeks), and chronic administration (12–18 weeks). Evaluations were conducted when plasma levels were at trough (just prior to dosing) and peak (three hours after dosing). The control group’s pain response was assessed twice during a single session, three hours apart.
The researchers found that, at baseline, compared with the control group, the heroin-dependent individuals demonstrated significantly shorter latencies to threshold and tolerance for cold-pressor pain. There was little change in pain response over time, with the exception of cold-pressor pain tolerance, for which hyperalgesia significantly increased in both groups at trough methadone/buprenorphine levels as the patients stabilized in treatment.
“We conclude that heroin-dependent individuals are hyperalgesic, and that once stabilized in treatment, are not different in pain responses regardless of treatment agent,” the authors write.