Performance of Local Anesthesia with Lidocaine among Opium Addicts and Non-Addicts; a Case Control Study

Introduction: Compared to ordinary people, addicts usually have a lower pain threshold. The current work attempts to compare the performance of local analgesia with lidocaine among opium addicts and non-addicts. Methods: In this case-control study, opium addicts and healthy patients with skin laceration referring to emergency departments of two educational hospitals were compared regarding the response to local anesthesia with lidocaine, as well as side effects. Results: 197 cases with the mean age of 43.44 ± 20.12 years were studied (72.1% male). 98 (49.8%) cases were addicts and 99 (50.2%) were healthy people. Two groups were similar regarding age (p = 0.281), sex (p = 0.666), and wound size (p = 0.272). The amount of pain reduction 5 (df =1.5, F=0.38, p = 0.88) and 10 (df =1.5, F=0.58, p = 0.72) minutes after lidocaine injection was not different between the groups. Subgroup analysis based on sex and age of patient did not show any differences between the groups (p > 0.1 for all analysis). The mean duration of analgesia was 16.4 ± 5.37 minutes in addicts and 16.95±1.79 in control group (p = 0.334). Conclusion: Lidocaine, as a commonly used local anesthetic agents, does not show different effects in addicts and non-addicts in repairing skin laceration.