Functional observation after morphine withdrawal : effects of SJP-005

Abstract

RATIONALE AND OBJECTIVE: SJP-005 (ketotifen and ibuprofen) is being developed as a potential new treatment for opioid withdrawal. Three studies were conducted to evaluate the early phase (acute, day 1) and late phase (days 2-12) effects of SJP-005 on discontinuation-induced morphine withdrawal. METHODS: Sprague-Dawley rats received subcutaneous morphine twice daily for 18 days and ceased on day 19. Twice daily, oral dosages of placebo or SJP-005 (1 mg/kg ketotifen and 15 mg/kg ibuprofen) were administered starting 4 days before (study 1), 2 days before (study 2), or immediately after (study 3) morphine cessation. Functional observations were made up to 12 h after treatment cessation on day 19 (early phase), and immediately after treatment on days 20-30 (late phase). Treatment effects (mean overall score, and individual symptoms) were compared with placebo using ANOVA, and Tukey's tests in case of multiple comparisons. RESULTS: Across the studies, the number of withdrawal signs on day 19 (early phase) and days 20-30 (late phase) was lower with SJP-005 compared with placebo. The effects of SJP-005 when treatment was initiated 2 days before morphine cessation by discontinuation were most pronounced and statistically significant in the late phase (F(1,18) = 14.10, p = 0.001). In particular, a significant reduction was observed in hypersensitivity to touch (F(1,18) = 13.65, p = 0.002). A 50% reduction in withdrawal symptoms was observed 9.0 days after placebo versus 4.5 days after SJP-005. After 9.0 days, all withdrawal symptoms were absent in the SJP-005 group, while symptoms in the placebo group were still evident on day 18. CONCLUSION: Compared to placebo, SJP-005 significantly reduced the incidence and duration of discontinuation-induced morphine withdrawal symptoms when treatment was initiated 2 days before morphine cessation.