Resorption and elimination kinetics of benzoic acid during chemical necrectomy in deep burns

Abstract Objective: Chemical necrectomy is an alternative to the surgical or sharp necrectomy for the removal of necrotic parts of the skin in the treatment of deep burns. The aim of our work was to monitor the dynamics of resorption and elimination of benzoic acid applied to the burnt skin. Methods: The set consisted of 10 patients (9 men; 1 woman) aged 25–57 years with IIb-III-degree skin burns. 40% benzoic acid in white petrolatum was applied to the burnt area to the extent of 3–5% of TBSA (total body surface area) for a period of 48 hours. The concentrations of benzoic acid, hippuric acid, and glycine in the serum was monitored at the 10th, 20th, 60th, 120th, 240th and 360th minute thereafter and further at the 12th, 24th, 48th, and 72nd hour; the excretion of hippuric acid in urine was monitored in six 12-hour intervals. Results: The highest concentration of benzoic acid in the serum was detected in the 60th minute sample (0.094±0.074 mmol/L) and of hippuric acid in the 120th minute sample (0.234±0.088 mmol/L) from the application of benzoic acid to the burnt skin. In the period between the 6th and 48th hour, the average concentration of benzoic acid in the serum ranged between 0.042 and 0.03 mmol/L. In this period there was also a significant decrease in serum glycine concentration (p<0.05). During the 48-hour application of benzoic acid to the burnt skin, 46.0–145 mmol of hippuric acid was excreted in urine. Conclusion: Chemical necrectomy with the use of 40% benzoic acid led only to a moderate increase of its concentration in the serum. After its resorption from the wound area it is transformed to hippuric acid, which is promptly excreted in urine.