Local infiltration of the surgical wounds with levobupivacaine, dexibuprofen, and norepinephrine to reduce postoperative pain: A randomized, vehicle-controlled, and preclinical study.

Postoperative pain may lead to poor wound healing, insomnia, and increased postoperative hospitalization. The objective of the study was to explore the effect of local infiltration of the surgical wound with levobupivacaine, dexibuprofen, and norepinephrine in postoperative pain. A randomized, parallel experimental design was applied in 40, 9-11-week-old Wister albino rats. A laparotomy was performed in all groups of 10 rats each. During surgery, the sutured muscle was infiltrated with 40μL of a normal saline (vehicle group), a normal saline containing 0.25% v/v levobupivacaine, 0.2mg/mL dexibuprofen, and 0.1mg/mL norepinephrine (treatment group) before skin closure. The same combination (negative control group) and a 10-fold higher dose (positive control group) were administered systematically. Rat Grimace Scale scores, based on facial expression, 24h after suturing of the tissues, histopathology and tensile strength of the surgical wound, two weeks after suturing of the tissues were measured. The one-way ANOVA and the two-tailed paired t-test/the Dunnett multiple comparisons test were used to compare the Rat Grimace Scale scores for pain within the group and between groups. The Kruskal-Wallis test and the one-way ANOVA/the Dunnett multiple comparisons test were used to compare the histopathology study and the tensile strength. The difference for statistical analysis was considered significant at the 95% of confidence level. The mean Rat Grimace Scale score at 24h for the treatment, negative control, and positive control groups was 1.945 (p=0.0025; q=3.257), 1.1 (p=0.1), and 1.95 (p=0.0021 q=3.547) respectively. The reduction in postoperative pain started within 1h after the suturing of the tissues in the treatment group. There were significant difference for epidermal and dermal regeneration (p=0.043), granulation tissue thickness (p=0.025), and angiogenesis (p=0.002) between treatment group and vehicle group. Tensile strength for the treatment group was 0.82±0.013N/cm2 (p=0.003; q=5.231). The rapid infiltration of surgical wounds with a low-dose levobupivacaine, dexibuprofen, and norepinephrine may reduce postoperative pain and increase the wound regeneration process.