The safety of topical anaesthetic and analgesic agents in a gel when used to provide pain relief at split skin donor sites

Post operative pain from split skin donor sites is a recognised problem. This study was carried out to assess the safety of a ‘depot’ preparation of bupivacaine and ketoprofen when applied to denuded dermis of a split donor site. Two groups of six patients each received either bupivacaine gel (2.5 mg/ml) or ketoprofen gel (1.6 mg/ml). One patient from each group was excluded as protocol was not followed. The mean surface area for bupivacaine was 106 cm2 (range 64–160) and the mean for ketoprofen was 130 cm2 (range 64–180). Blood samples were obtained before application and at 10, 20, 30, 60, 120, 240 and 480 min after application. Serum levels were assayed using Gas Liquid Chromatography and High Pressure Liquid Chromatography. Bupivacine levels peaked at 120 min, mean level obtained was 0.07 μg/ml (range 0.03–0.1). Ketoprofen levels also peaked at 120 min and the mean level obtained was 0.20 μg/ml (range 0.12–0.27). The reported toxic serum level for bupivacaine was 4 μg/ml and for ketoprofen is 1128 μg/ml. In conclusion, these preparations, when applied to denuded dermis of a split skin donor site, are unlikely to result in toxic levels.