Antiallodynic and Antihyperalgesic Activities of Fentanyl-Loaded Dermal Clay Dressings in Rat Model of Second-Degree Burn Injury

Second-degree burn injury is the most common type of burn injury, which usually takes 2-3 weeks for complete healing. However, such patients suffer with intense pain associated with development of hyperalgesia and allodynia. Here, we prepare a silver clay patch using montmorillonite clay, betaine, and silver nitrate. Later, the silver clay patches were loaded with fentanyl. Furthermore, the patches were fabricated into burn wound dressings. The dressings were first subjected to ex vivo skin penetration studies and were later evaluated for thermal hyperalgesia and mechanical allodynia using second-degree burn injury rodent model. Our results show that application of fentanyl-loaded dermal clay (FLDC) dressings for 3 h showed significant increase of paw withdrawal latency (p <0.001) against hyperalgesia starting from 30 min after removal of patch to up to 6 h. Similarly, the FLDC dressings also potentiated the paw withdrawal threshold for up to 4 h after application (p <0.001). From these studies, we can conclude that FLDC dressings are ideal topical formulations for better management of pain in second-degree burns.