PALM SPRINGS, CA — Patients with chronic neuropathic pain can be safely and effectively converted and maintained on once-daily hydromorphone extended-release tablets (OROS® hydromorphone ER), a study reported during the 2012 American Academy of Pain Medicine Annual Meeting.

An open-label, single-center, 12-week study converted opioid-tolerant patients (taking ≥60mg/day oral morphine or equivalent for ≥1 week) with chronic neuropathic pain from their previous opioid and titrated to adequate analgesia with OROS® hydromorphone ER over two weeks, reported Srinivas Nalamachu, MD, of the International Clinical Research Institute, Leawood, KS, and colleagues. The two most common primary diagnoses were diabetic neuropathy (30%) and peripheral neuropathy (27%).

Patients were converted using a 5:1 morphine:hydromorphone equianalgesic dosing ratio, with an initial dose of approximately 50% of the calculated equianalgesic dose. Dose titration occurred every 3–4 days over a two-week period. Patients were not allowed to take any other extended-release or long-acting opioid, but were allowed to continue current medication for breakthrough pain.

The primary efficacy measure was change from baseline in “average pain,” question No.5 of the Brief Pain Inventory (BPI) scale, assessed at Week 12. The Pain Quality Assessment Scale (PQAS) and the Global Assessment of Treatment Satisfaction were included as secondary endpoints.

A total of 30 patients were enrolled and received ≥1 dose of OROS® hydromorphone ER. Mean age was 58 years, and 67% were male. The mean daily morphine equivalent dose at baseline was 163.7mg.

“Patients were initially converted to a mean daily OROS® hydromorphone ER dose of 18.1mg and subsequently titrated to a mean daily dose of 26.4mg,” the investigators noted. Daily doses of ≥16mg of OROS® hydromorphone ER were required in 80% of patients. Between baseline and Week 12, BPI “average pain” decreased from 5.9 to 4.7 (P=0.058) and PQAS decreased from 107.7 to 82.8 (P<0.01). Sleep interference scores improved from baseline at all time points (P<0.01). The majority of patients (81%) were either very satisfied or satisfied with treatment. Overall, 12 patients experienced adverse events (AEs) considered to be treatment-related. The most common AE was headache, occurring in three patients. One severe case of pneumonia and one moderate case of heart arrhythmia were reported, but both were considered as unlikely to be associated with OROS® hydromorphone ER therapy.

“Based on the current results, larger placebo-controlled trials are warranted to more fully evaluate the effect of OROS® hydromorphone ER in patients with chronic neuropathic pain,” Dr. Nalamachu concluded.