Opioid-Induced Hyperalgesia in Prescription Opioid Abusers: Effects of Pregabalin

The clinical management of pain in prescription opioid abusers presents a challenge to the health care professional. Investigators have novel pilot data showing that the GABA-agonist gabapentin (GPN) significantly decreases opioid-induced hyperalgesia (OIH) in methadone patients (Compton et al., 2009), providing the first empirical evidence of a pharmacotherapy for OIH in opioid abusers. The work of Gore and colleagues (2011) showed that pregabalin (PGB), a GABA analogue succeeding GPN, was shown to decrease opioid use in patients with neuropathic pain in patients, suggesting an anti-hyperalgesia effect not observed in the matched cohort receiving GPN. The proposed research will comprehensively evaluate the efficacy of PGB in treating opioid-induced hyperalgesia (OIH) in a well-described population of prescription opioid abusers (POAs) with chronic pain and on Suboxone (buprenorphine) or methadone therapy. A pressing need for such investigation is presented by the rising number of POAs presenting for treatment (SAMHSA, 2010; 2011), and for whom, chronic pain is a common co-morbidity. The proposed work is anticipated to provide vital and timely information on the efficacy of PGB in the treatment of OIH in prescription opioid abusers on Suboxone or methadone therapy. Following recruitment and screening, 75 subjects assigned to the active medication group will receive pregabalin 400 mg/day, a dose well-within published guidelines of 300-600 mg/day for the treatment of neuropathic pain (http://www.pfizerpro.com/hcp/lyrica/phndosing). During the first week of treatment, subjects will be quickly titrated up to the assigned daily PGB dose of 400 mg/day PO (50mg BID x 2 days; 100mg BID x 2 days; 150mg BID x 2 days, with full dosage of 400mg administered on day 7 ), or maximum dose tolerated) for six weeks. 75 subjects will be assigned to receive matched and undergo identical titration and study activities under double-blind conditions. Study staff will evaluate subjects daily by phone during titration; thereafter they will be seen weekly at study sessions. Tapering of medication will begin at the end of week 6. The severity of chronic pain will be measured at each time point using two standardized self report tools which report on pain severity (McGill Pain Questionnaire) and pain-related disability (Brief Pain Inventory). Opioid-induced hyperalgesia will be measured at each time point using a standardized cold pressor trial, and performance at baseline will be compared to performance following PGB/placebo administration over time.