D. Lim

Curcumin Could Prevent the Development of Chronic Neuropathic Pain in Rats with Peripheral Nerve Injury

Background Peripheral nerve injury results in chronic neuropathic pain characterized by allodynia and/or spontaneous pain. It has been suggested that activation of mitogen-activated protein kinases such as extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) contribute to the neuropathic pain. Objectives We investigated if curcumin could prevent the development of neuropathic pain in rats with chronic constriction injury (CCI) of the sciatic nerve. Methods The animals were divided into 3 groups. In the curcumin treatment group (n = 10), curcumin (50 mg/kg/d PO) was administered once daily from 1 day before CCI to 7 days after CCI. The rats in the sham group (n = 10) and CCI group (n = 10) received a control vehicle. The mechanical allodynia was assessed using von Frey at 1, 3, 5, and 7 days after nerve injury. Western blots were used to evaluate the levels of p-ERK, p-JNK, and phosphorylation of NR1 (p-NR1) subunits of N-methyl-D-aspartate in the spinal dorsal root ganglion. Results In the CCI group, mechanical allodynia was observed during 7 days after nerve injury. However, curcumin treatment reversed the mechanical allodynia 7 days after nerve ligation. There were no differences in the expression of p-ERK, p-JNK, and p-NR1 between the sham and curcumin groups. However, the expression of p-ERK, p-JNK, and p-NR1 in the CCI group were higher than the sham group and curcumin group, respectively (P < 0.05). Conclusions Treatment with curcumin during the early stages of peripheral neuropathy can prevent the development of chronic neuropathic pain.

Reactive oxygen species in rats with chronic post-ischemia pain

Background: An emerging theme in the study of the pathophysiology of persistent pain is the role of reactive oxygen species (ROS). In the present study, we examined the hypothesis that the exogenous supply of antioxidant drugs during peri‐reperfusion would attenuate pain induced by ischemia/reperfusion (IR) injury. We investigated the analgesic effects of three antioxidants administered during peri‐reperfusion using an animal model of complex regional pain syndrome‐type I consisting of chronic post‐ischemia pain (CPIP) of the hind paw.

Reduction of pain on injection of propofol: combination of pretreatment of remifentanil and premixture of lidocaine with propofol

Backgrounds and objective: There is a high incidence of pain following intravenous injection of propofol, and many studies have been conducted to find a way of reducing this. The administration of lidocaine and, recently, remifentanil has also been used for this purpose, but it is only partially effective. Thus, the purpose of this study was to investigate the analgesic effect of a combination of pretreatment with remifentanil and premixture of lidocaine with propofol and to compare either treatment alone during propofol injection in dorsal hand‐veins. Methods: In a prospective, randomized, double‐blinded trial, we studied 141 adult patients scheduled for elective surgery. The combination of pretreatment of remifentanil (0.35 &mgr;g kg−1 min−1) and a premixture of lidocaine with propofol (mixture of propofol 1% and lidocaine 1% in a 10 : 1 ratio) was compared with either treatment alone in the prevention of pain on propofol injection. Pain was assessed on a four‐point scale (0 = none, 1 = mild, 2 = moderate, 3 = severe) during propofol injection. Patients in Group B received remifentanil (0.35 &mgr;g kg−1 min−1) 30 s before the injection of propofol. Results: The reduction of pain on propofol injection was similar in both the remifentanil pretreatment and lidocaine premixture groups (62.2% vs. 62.2%). Combination therapy was associated with a higher incidence of patients without pain (91.3%) than either treatment alone (P < 0.001). On analysing the injection pain scores, we found a significant reduction of the score in the remifentanil and lidocaine Group C compared with the lidocaine Group A (P < 0.001) and the remifentanil Group B (P < 0.001). Conclusions: The combination of pretreatment of remifentanil and premixture of lidocaine with propofol was more effective in reducing the incidence of pain on injection of propofol than either treatment alone.

A Combination of Lidocaine (Lignocaine) and Remifentanil Reduces Pain during Propofol Injection

AbstractObjective: Pain on injection is a well known adverse effect of propofol. The purpose of this study was to compare the analgesic effect of a lidocaine (lignocaine)/remifentanil combination compared with either lidocaine alone or remifentanil alone during propofol injection for induction of anaesthesia. Methods: In a randomised, double-blind, prospective trial, 129 patients were allocated to one of three groups (each n = 43) receiving lidocaine 20mg, remifentanil 0.3 μg/kg or lidocaine 20mg plus remifentanil 0.3 μg/kg as pretreatment, followed by injection of 5mL of 1% propofol. Pain severity was evaluated on a four-point scale. Results: Two patients (4.7%) complained of pain in the lidocaine plus remifentanil group compared with 15 (35.7%) in the lidocaine alone group and 18 (42.9%) in the remifentanil alone group (p < 0.001). There was no significant difference in the incidence of injection pain between the lidocaine alone and remifentanil alone groups (p = 0.21). Conclusion: Pretreatment with a combination of lidocaine and remifentanil is more effective than either pretreatment alone in reducing pain on injection of propofol.