ZINC-CONTAINING WOUND DRESSINGS ENCOURAGE AUTOLYTIC DEBRIDEMENT OF DERMAL BURNS

Zinc has many actions that may promote debridement and wound healing. Perhaps, most importantly, zinc is a cofactor for numerous metalloprot einases, including collagenases that are important in the breakdown of connective tissue collagen. This study evaluated the action of zinc i on-containing preparations on debridement in a rat burn-wound model. T wo zinc-containing ointments were studied. The first contained 4.8 mu g zinc ion/g and the second contained 431 mu g zinc ion/g. Standard fu ll-thickness scald bums were produced on the dorsum of rats (n = 7) by a ten-second immersion in boiling water. After 24 hours, two rubber t emplates were affixed, one on each side of the dorsum. Each contained three square 4 cm(2) wells, spaced 1 cm apart and 3 mm deep. One templ ate well received the low-concentration zinc ointment and another well received the high-concentration zinc ointment. The contralateral well either on the right or left side was dressed with saline. The locatio n of treatment sites was alternated in an ordered manner. Variations i n debridement due to location were canceled out by the paired configur ation of the treatment sites. The burn within each well was scraped wi th a spatula two hours after application of the dressings, the wounds redressed and scraped again 24 hours later. The templates were then re moved and the debrided and surrounding undebrided tissues were harvest ed, processed histologically by hematoxylin and eosin staining, and vi ewed microscopically. The thickness of the debrided and undebrided tis sues was measured by image analysis and percent debridement calculated . Mean percent debridement (1 standard deviation) were 19.5 +/- 8.6 pe rcent for saline controls, 24.2 +/- 3.7 percent for low-concentration zinc ion ointment, and 31.9 +/- 10.9 percent for high-concentration zi nc ion ointment (p = 0.001 versus saline controls). These results indi cate that a topical preparation containing a relatively high zinc conc entration can significantly encourage autolytic burn-wound debridement .