Abstract
Introduction
Sulfur mustard (SM) is a chemical weapon first used in 1917 and in 11 subsequent regional conflicts including use by ISIS in Syria in 2016. SM skin exposure results in burns that are indolent, recurrent and hard to treat. Despite 100 years of experience, there is no standard of care for SM burns. We tested silver-nylon dressings in a porcine model of partial thickness SM injury.
Methods
The study was performed in an AAALAC-approved facility under Good Laboratory Practices (GLP) standards. A total of 1320 superficial or deep partial thickness burns were produced in 165 Gottingen minipigs by vapor cap exposure. The wounds were then debrided with 7 days of saline wet/wet dressings. Silver-nylon dressings were applied and changed daily, every 4 days or every 7 days. Control dressings were silver sulfadiazine changed daily. Dressings were left intact for 30 days followed by 7 days of no treatment. Animals were euthanized and wounds assessed by histopathology (primary endpoint). The non-inferiority margin for histopathology score was 1.5 (10% of maximum possible score).
Results
There was no mortality or wound infection seen. Silver-nylon when applied once every 7 days to superficial or deep wounds was not inferior to the comparator treatment, SSD on gauze, as evaluated by histopathology (Δ =0.38 95% CI = 0.15, p = 0.0001). There was no statistical difference when comparing silver nylon applied daily, every 4 days or every 7 days in either superficial or deep wounds Chart # 1). Blood silver levels were drawn pre-study, mid study and at autopsy. Blood silver levels were negative in all cases (n= 480). At study end, silver ion was detected in virtually all wounds. Mean skin silver ion levels in wounds treated with daily SSD on gauze or BCD bandage every 1, 4, or 7-days were 3.74, 3.61, 5.43, and 4.40 μg/g, respectively for deep dermal wounds and 2.41, 1.91, 3.75, and 2.73 μg/g,respectively for superficial dermal wounds.There was no statistically significant difference between any of the bandage treatments with regard to silver ion levels in skin punch biopsies collected on Study Day 46.
Conclusions
Silver nylon dressings provide effective treatment for sulfur mustard burns. As in prior studies, silver-nylon provides high wound silver levels without systemic absorption. The data from this study was submitted to the US Food and Drug Administration, resulting in the first-ever FDA clearance for a product indicated to treat sulfur-mustard skin burns.
Applicability of Research to Practice
Silver-nylon dressings can be successfully used to treat cutaneous partial-thickness sulfur mustard skin burns.
Chemical Safety Concerns of Sulfur Mustard Analog, 2-Chloroethyl Ethyl Sulfide, in Laboratory Study
