Effect of Hydration on Barrier Performance of Third-Degree Burn Eschar

Infection is the primary source of mortality in burn patients. One of the main treatment methods of burn wound infections is topical antimicrobial therapy, in which drugs have to permeate a dead tissue called eschar. Unfortunately, most antimicrobial agents can not permeate eschar in therapeutic levels. Surprisingly, permeation properties of this barrier and effects of chemical or environmental conditions on it, including hydration level which is the subject of the present investigation, is not thoroughly studied as yet.

Here, permeation of silver sulfadiazine (SSD), the most frequently used topical agent in burn management, from its’ 0.6 mg/ml solution through human third-degree burn eschar was studied in vitro at different hydration levels of fully-hydrated, semi-hydrated and dry eschar. The experiments were performed at 32°C, using Franz-type diffution cells. Hydration level was adjusted by controlling the contact condition of eschar tissue with an aqueous medium.

Results showed that hydration can severely affect permeation of SSD through the burn eschar. Permeation of SSD through fully-hydrated tissue was about 20 times more than that of semi-hydrated samples. Permeation of SSD through dry eschar was initially (up to 3 h) more than those of semi- or fully hydrated tissues, but it ceased and reached a plateau at this time point, while for the other systems continued and became more than that of the dry eschar at later stages. The cumulative amount of drug permeated through the fully-hydrated tissue in 8 h was about 30 times more than that of the dry eschar.

Our results showed that hydration can clearly improve permeation of SSD and possibly other drugs through third-degree burn eschar. A property which could easily change during patient management, e.g., by covering, washing, or application of occlusive formulations.