Purpose: Second degree burn injury is the most common type of burn injury which is usually with intense pain associated with development of hyperalgesia and allodynia. Dermal silver clay patch systems are effective in wound healing and would serve as a great wound dressing in addition to prevent of infection. The objective of this study is to load these silver clay patch system with subtherapeutic level of fentanyl (68% less than commercial fentanyl transdermal patches) and evaluate them for anti-allodynic and anti-hyperalgesic activity in second degree burn injury.
Methods: Dermal silver clay patches were prepared using Montmorillonite clay, betaine and silver nitrate. Later, the silver clay patches were loaded with fentanyl. Later, the patches were fabricated into burn wound dressings. The dressings were first subjected to ex vivo skin penetration studies using franz diffusion cells in human cadaver skin. They were later evaluated for thermal hyperalgesia using Hargreave’s test apparatus and mechanical allodynia using dynamic plantar aesthesiometer in second degree burn injury rodent model.
Results: Therapeutically effective amount of Fentanyl (6µg/cm2) was penetrated into the human cadaver skin. Second degree burn injury was successfully achieved at 700C for 30min using super soldering station in rat paws. Application of FLDC dressings on 3rd day for 3h (based on the skin penetration studies to obtain 3µg penetration dose) showed significant increase of paw withdrawal latency (p<0.001) starting from 30min after removal of patch to up to six hours in ipsilateral paw compared to the silver clay patch. Similarly, application of FLDC dressings for 3h significantly potentiated the paw withdrawal threshold of the injured hind paw up to 5h compared to the silver clay patch group (p<0.001).
Conclusion: This study demonstrates that significantly lower loading of fentanyl (80 mcg/cm2 vs 250 mcg/cm2) to the silver clay patches and fabricating them as wound dressings can significantly attenuate hyperalgesia and allodynia associated with burn injuries. Thus from these observations, we can conclude that FLDC dressings could be an ideal topical dressing for efficient pain management in second-degree burns, as it can ameliorate pain in addition to supporting the wounds.
Kris Rangan– Materials Modification, Inc., Virginia
Tirumalai S. Sudarshan– Materials Modification, Inc., Virginia
Narasimha Murthy– Professor-Pharmaceutics and Drug Delivery, University of Mississippi, University, Mississippi