title: Gabapentin improves cold-pressor pain responses in methadone-maintained patients.
abstract: Individuals on methadone maintenance for the treatment of addiction (MM) are demonstrated to be hyperalgesic to cold-pressor pain in comparison to matched controls and ex-opioid addicts, a finding described as clinical evidence of opioid-induced hyperalgesia (OIH). Interestingly, opioids induce hyperalgesia via many of the same neuro-inflammatory and central sensitization processes that occur with the development of neuropathic pain. Evaluated in this study was the efficacy of a key pharmacotherapy for neuropathic pain, gabapentin (GPN), to reverse OIH in MM patients. Utilizing a clinical trial design and double blind conditions, changes in cold-pressor pain threshold and tolerance following a 5-week trial of GPN (titrated to 2400mg/day) were evaluated at peak and trough methadone plasma levels in a well-characterized MM sample. Drug abstinence was encouraged via an escalating payment schedule, and compliance monitored via pill counts and GPN plasma levels; entered into the analyses were only those subjects compliant and abstinent throughout the study (approximately 45%). Utilizing change scores from baseline, significant improvements in cold-pressor pain threshold and pain tolerance were observed at both peak and trough methadone levels (p<0.05). Notably, drop-out rates due to medication side effects were low (2%) and the medication was well-tolerated. These results support that GPN, as prescribed for the treatment of neuropathic pain, is effective in decreasing OIH in patients who are abstinent and stable in methadone treatment.
authors.affiliation: School of Nursing, University of California, Los Angeles, CA 90095, United States. pcompton@sonnet.ucla.edu
authors.forename: Peggy
authors.initials: P
authors.lastname: Compton
authors.forename: Priscilla
authors.initials: P
authors.lastname: Kehoe
authors.forename: Karabi
authors.initials: K
authors.lastname: Sinha
authors.forename: Matt A
authors.initials: MA
authors.lastname: Torrington
authors.forename: Walter
authors.initials: W
authors.lastname: Ling
mesh_terms: D000328:Adult; D000588:Amines / Q000009:adverse effects / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000009:adverse effects / Q000494:pharmacology*; D003080:Cold Temperature; D003509:Cyclohexanecarboxylic Acids / Q000009:adverse effects / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D000077206:Gabapentin; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy / Q000209:etiology; D008297:Male; D008691:Methadone / Q000009:adverse effects* / Q000097:blood / Q000627:therapeutic use*; D008875:Middle Aged; D009294:Narcotics / Q000009:adverse effects* / Q000097:blood / Q000627:therapeutic use*; D009293:Opioid-Related Disorders / Q000534:rehabilitation; D010147:Pain Measurement / Q000187:drug effects*; D017288:Pain Threshold / Q000187:drug effects; D010349:Patient Compliance; D011312:Pressure; D005680:gamma-Aminobutyric Acid / Q000009:adverse effects / Q000494:pharmacology*
chemical_list: D000588:Amines; D018712:Analgesics, Non-Narcotic; D003509:Cyclohexanecarboxylic Acids; D009294:Narcotics; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D008691:Methadone