(834): Topical sterile lidocaine patch to reduce postoperative pain and decrease need for oral analgesics after inguinal herniorrhaphy

Abstract

We designed a sterile lidocaine patch for application to a closed wound to reduce pain and systemic analgesic use after inguinal herniorrhaphy. We conducted a double-blind placebo(P)controlled parallel, dose-response study comparing the daily application of a 3.5% lidocaine patch to a 10% lidocaine patch for 48 hours after surgery. 221 subjects who underwent unilateral herniorrhaphy using a tension-free mesh were randomized to one of three patches. Anesthesia was general or spinal and no local anesthetic was injected at closure to determine the time of onset of the lidocaine in the patch. Rescue medication was oral methimazole, a short-acting analgesic. Pain intensity (PI) was assessed at time points for up to 48 hours. The AUC for PI from 2-48 hours was P 109, 3.5% 102, and 10% 89,(p=0.05). The AUC for PI from 2-24 hours was P 63, 3.5% 60, and 10% 52 (p= 0.045) and from 24-48 hours was P 47, 3.5% 42, and 10% 34 (p= 0.03). The pain reduction for 10% vs. P from 2 to 48 hours was 19%, from 2-24 hrs was 18% and from 24-48 hours was 27%. The number of rescue analgesic doses over the 48 hours was P 101, 3.5% 81, 10% 65 (p= 0.01), a reduction of 36%(10% patch vs. placebo). The lesser magnitude of AUC in the first 24 hours indicates the onset of the lidocaine patch is 2 to 3 hours. The safety of a 10% lidocaine patch was demonstrated by a single wound infection and no effect on wound healing. A 10% sterile lidocaine patch applied daily over the wound was shown to be safe and effective in reducing post operative pain after inguinal herniorrhaphy. Most importantly, a decrease in the use of oral rescue analgesic after surgery, thereby reducing post-operative side effects. We designed a sterile lidocaine patch for application to a closed wound to reduce pain and systemic analgesic use after inguinal herniorrhaphy. We conducted a double-blind placebo(P)controlled parallel, dose-response study comparing the daily application of a 3.5% lidocaine patch to a 10% lidocaine patch for 48 hours after surgery. 221 subjects who underwent unilateral herniorrhaphy using a tension-free mesh were randomized to one of three patches. Anesthesia was general or spinal and no local anesthetic was injected at closure to determine the time of onset of the lidocaine in the patch. Rescue medication was oral methimazole, a short-acting analgesic. Pain intensity (PI) was assessed at time points for up to 48 hours. The AUC for PI from 2-48 hours was P 109, 3.5% 102, and 10% 89,(p=0.05). The AUC for PI from 2-24 hours was P 63, 3.5% 60, and 10% 52 (p= 0.045) and from 24-48 hours was P 47, 3.5% 42, and 10% 34 (p= 0.03). The pain reduction for 10% vs. P from 2 to 48 hours was 19%, from 2-24 hrs was 18% and from 24-48 hours was 27%. The number of rescue analgesic doses over the 48 hours was P 101, 3.5% 81, 10% 65 (p= 0.01), a reduction of 36%(10% patch vs. placebo). The lesser magnitude of AUC in the first 24 hours indicates the onset of the lidocaine patch is 2 to 3 hours. The safety of a 10% lidocaine patch was demonstrated by a single wound infection and no effect on wound healing. A 10% sterile lidocaine patch applied daily over the wound was shown to be safe and effective in reducing post operative pain after inguinal herniorrhaphy. Most importantly, a decrease in the use of oral rescue analgesic after surgery, thereby reducing post-operative side effects.