Original Article Effect of Hydration on Barrier Performance of Third-Degree Burn Eschar Behzad Sharif Makhmal Zadeh a and Hamidreza Moghimi a,b* a School of Pharmacy and b Pharmaceutical Sciences Research Center, Shaheed Beheshti University of Medical Sciences, Tehran, Iran. Abstract 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. Keywords: Burn Eschar; Wound; Permeation; Hydration; Enhancement; Silver sulfadiazine. Introduction Burn wound infection is the primary source of morbidity and mortality in burn patients. Burn injuries occur in every age group and both sexes. Depth of burn injury depends on the burning agent, temperature and length of exposure to the burning agent. The equilibrium temperature for skin is approximately 44° C. This temperature can be tolerated for up to 6 h without burning (1). Time-temperature relationship in the depth and degree of damage to skin is very important in the physiopathology of burn. As temperature increases, various enzyme systems begin to * Corresponding author: E-mail: hrmoghimi@yahoo.com Copyright © 2006 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services Iranian Journal of Pharmaceutical Research (2006) 3: 155-161 Received: November 2005 Accepted: February 2006 Archive of SID www.SID.ir