Transdermal Fentanyl Solution Provides Long-term Analgesia in the Hind-paw Incisional Model of Postoperative Pain in Male Rats.

Background: A recently developed transdermal fentanyl solution was hypothesized to be effective for non-invasive postoperative analgesia in rats.

Materials And Methods: Thirty-nine male Sprague-Dawley rats were treated once with 0.1, 0.33 or 1.0 mg/kg transdermal fentanyl solution at the skin of the scruff 1 h prior to subjected to hind-paw surgery, and compared to non-treated animals. All rats were tested for nociceptive response in the electronic von Frey (EVF) test between 1 and 72 h postoperatively, and assessed daily with regards to facial expression, body weight changes and welfare score.

Results: Fentanyl treatment at all doses significantly reduced nociceptive response in the EVF test throughout the 72 h of experimentation, reduced facial expressions on all days postoperatively, slightly reduced the body weight and improved postoperative welfare parameters.

Conclusion: The present study indicates that transdermal fentanyl solution seems to be an effective, non-invasive and long-lasting analgesic regimen in male rats.