Mast cell stabilizer ketotifen fumarate reverses inflammatory but not neuropathic-induced mechanical pain in mice.

INTRODUCTION: Mast cell (MC) activation could establish a positive feedback loop that perpetuates inflammation and maintains pain. Stabilizing MCs with ketotifen fumarate (KF) may disrupt this loop and relieve pain. OBJECTIVE: We aimed to test the effect of treatment with KF in pain assays in mice and in a case series of patients with chronic widespread pain. METHODS: The analgesic effect of KF was tested in CD-1 mice injected with formalin, complete Freund's adjuvant, or subjected to spared nerve injury. In addition, wild-type (C57BL/6) and MC-deficient (C57BL/6-Kit W-sh/W-sh) mice were injected with formalin or complete Freund's adjuvant and treated with KF. Patients with chronic widespread pain (n = 5; age: 13-16 years) who failed to respond to standard of care participated in a 16-week treatment trial with KF (6 mg/d). Ketotifen fumarate's therapeutic effect was evaluated using the patient global impression of change. RESULTS: In the mouse experiments, KF produced dose- and MC-dependent analgesic effects against mechanical allodynia in the acute and chronic inflammatory pain but not neuropathic pain assays. In the patient case series, 4 patients reported that activity limitations, symptoms, emotions, and overall quality of life related to their pain condition were "better" or "a great deal better" since beginning treatment with KF. This was accompanied by improvements in pain comorbid symptoms. CONCLUSION: Treatment with KF is capable of reducing established inflammatory-induced mechanical nociception in an MC-dependent manner in mice, and it may be beneficial for the treatment of chronic pain conditions.

Nebulized analgesia during laparoscopic appendectomy (NALA): A randomized triple-blind placebo controlled trial.

PURPOSE: Postoperative pain remains a considerable concern for patients and families. We assessed whether nebulized ropivacaine reduces morphine consumption and pain after laparoscopic appendectomy for uncomplicated appendicitis in children. METHODS: Patients 7-17 years old with uncomplicated appendicitis were randomized to ropivacaine (intervention arm) or saline nebulization (placebo arm) at the onset of laparoscopy. Nonconsenting individuals were treated with standard care and invited to provide clinical data (baseline arm). The primary outcome was in-patient morphine utilization. Secondary outcomes included pain scores at multiple time-points, markers of recovery, operative times, and surgeon satisfaction. The trial was registered (NCT02624089). RESULTS: Study enrollment was 116 patients over a 1-year period: Intervention (n = 43), Placebo (n = 39), Baseline (n = 34). No differences in baseline characteristics were noted between groups. No difference was noted in overall in-patient morphine consumption between randomized groups (0.31 vs. 0.35 mg/kg, p = 0.42) or between ropivacaine and baseline (0.31 vs. 0.277 mg/kg, p = 0.62). Although operative times were comparable between groups, 63% of surgeon respondents felt that nebulization obscured visualization. CONCLUSION: Nebulized ropivacaine did not reduce postoperative morphine consumption or pain scores after laparoscopic appendectomy for simple appendicitis in children. Given that it decreases visualization and likely increases costs, nebulized administration of intraperitoneal analgesia does not appear warranted in this context. TYPE OF STUDY: Treatment study. LEVEL OF EVIDENCE: Level I.