Sublingual Dexmedetomidine Shows Analgesic Efficacy in Patients with Chronic Low Back Pain

AUSTIN, TX—Patients with chronic low back pain treated with REC1100, a sublingual formulation of dexmedetomidine, showed a significant decrease in mean Visual Analog Scale of Pain (VASPain) scores two hours after dosing compared with those receiving placebo, investigators reported during the American Pain Society's 30th Annual Scientific Meeting.

Dexmedetomidine is a potent α2-agonist observed to produce postoperative analgesic and opioid-sparing effects when administered intravenously. Overall, patients in the active treatment group had statistically significant decrease in pain intensity scores of -19.7 compared with -8.4 for placebo (P=0.0408), noted Lynn R. Webster, MD, from Lifetree Clinical Research and Pain Clinic, Salt Lake City, UT and colleagues.

The study evaluated the safety, pharmacokinetics, and analgesic efficacy of REC1100 in 21 patients with chronic low back pain with and without a history of opioid use for back pain. Patients were randomized to treatment with a 50µg dose of REC1100 or matching placebo in a double-blind, placebo-controlled, single dose crossover fashion, followed by an open-label phase with a 50µg repeated dose of REC1100. Opioids were not permitted prior to dosing in the crossover periods, while opioid regimens were maintained throughout the repeated dose phase. Analgesia was measured using a 100mm VASPain.

During the crossover phase, the mean change from baseline in pain intensity scores was lower in REC1100 patients vs. placebo, at all post-dose study time points; mean pre-dose VASPain scores were similar for REC1100 and placebo (55.2 and 55.1, respectively). The mean maximum change from baseline in pain intensity for REC1100 and placebo at any time was -26.8 vs. -17.6 respectively (P=0.0188). Mean predose VASPain scores were lower before each treatment in patients with a history of opioid use than those without; crossover REC1100 group (46.3 vs. 61.9), crossover placebo group (50.11 vs. 58.83); both respectively.

During the repeated dosing phase, peak mean VASPain reductions remained numerically greater in nonopioid users vs. opioid users (-20.4 vs. -16.2). The peak mean percent change from baseline in VASPain scores was similar for opioid users and non-users following both doses of REC1100 (-36.7 and -33.6% vs. -33.3% and -40.2%) Doses of REC1100 were well tolerated. None of the patients discontinued the study and no serious adverse events were observed. Use of opioid medications did not appear to effect the single or repeated dose mean plasma profile for dosing with REC1100.

The improvements in VASPain scores observed in this study support the analgesic efficacy of REC1100 in patients with chronic low back pain alone and in combination with opioid medications, the investigators concluded, noting that additional research is warranted to evaluate REC1100 in larger and more diverse pain populations.