title: Novel strategy for the control of postoperative pain: long-lasting effect of an implanted analgesic hydrogel in a rat model of postoperative pain.
abstract: BACKGROUND
  The administration of nonsteroidal anti-inflammatory drugs (NSAIDs) is the most common nonopioid analgesic currently used for postoperative pain management. We tested the sustained analgesic effect of ketoprofen emanating from a biodegradable gelatin hydrogel in a rat model of postoperative pain.
  
  
  METHODS
  A sheet of analgesic-infiltrated hydrogel was inserted below the plantaris muscle at the end of surgery. Mechanical thresholds were measured by use of von Frey filaments before and 2 weeks after the operation. The effect of ketoprofen on the postoperative pain was also assessed immunohistochemically by assessing microglial activation in the spinal cord with anti-OX-42 and phosphorylated p38 mitogen-activated protein kinase antibodies.
  
  
  RESULTS
  Implantation of ketoprofen-infiltrated gelatin hydrogel exerted a sustained analgesic effect for 1 week after the operation. Preemptive analgesia with zaltoprofen, another NSAID, produced an additive analgesic effect in conjunction with the ketoprofen-infiltrated hydrogel. Microglial activation was attenuated by the treatment with ketoprofen-infiltrated hydrogel on day 3 after the incision.
  
  
  CONCLUSIONS
  These results demonstrate that ketoprofen was effective in reducing mechanical hypersensitivity for 1 week in a rat model of postoperative pain and that the implantation of NSAID-infiltrated gelatin hydrogel may serve as a useful analgesic method for the long-term relief of patients after surgery.
authors.affiliation: Department of Surgery, Kansai Medical University, Osaka, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Araki
authors.forename: Masaki
authors.initials: M
authors.lastname: Kaibori
authors.forename: Shinji
authors.initials: S
authors.lastname: Matsumura
authors.forename: A-Hon
authors.initials: AH
authors.lastname: Kwon
authors.forename: Seiji
authors.initials: S
authors.lastname: Ito
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004343:Drug Implants; D020100:Hydrogels; D006930:Hyperalgesia / Q000503:physiopathology / Q000517:prevention & control; D007660:Ketoprofen / Q000008:administration & dosage*; D008297:Male; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D010149:Postoperative Pain / Q000175:diagnosis / Q000503:physiopathology / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004343:Drug Implants; D020100:Hydrogels; D007660:Ketoprofen