A prospective, randomized, blind comparison between saline, calcium gluconate and diphoterine for washing skin acid injuries in rats: effects on substance P and beta-endorphin release.

BACKGROUND AND OBJECTIVE: A randomized, blind study to evaluate the effects on beta-endorphin and substance P release after washing acid burns with 0.9% saline, calcium gluconate or diphoterine in a model of chemical burn in rats.

METHODS: Twenty Sprague-Dawley rats (approximate weight 250 g) were anaesthetized with ketamine (30 mg kg(-1) intramuscularly) and then given an acid injury on the back skin with 0.5 mL of hydrochloric acid 52%. The rats were then randomly allocated to receive no washing (control group, n = 5), washing with normal saline (0.9% NaCl) (n = 5), 10% calcium gluconate (n = 5) or diphoterine (n = 5). Blood concentrations of substance P and beta-endorphin were measured 6 h, 48 h and 7 days after the chemical burn. An independent blinded observer evaluated wound healing at the 7th day.

RESULTS: Seven days after burn wound healing was almost complete only in rats treated with diphoterine. Plasma concentrations of substance P were lower in rats receiving skin flushing with diphoterine compared to the other groups at 6 and 48 h after acid burn (P < 0.05 and P < 0.05, respectively); this was also associated with higher concentrations of beta-endorphin at day 7 (P < 0.05).

CONCLUSIONS: Skin flushing with diphoterine reduced substance P release during the first 48 h after burn, and was associated with better wound healing and higher concentrations of beta-endorphin 7 days later when compared with normal saline or 10% calcium gluconate.