Sameridine is safe and effective for spinal anesthesia: a comparative dose-ranging study with lidocaine for inguinal hernia repair

Lidocaine vs. Other Local Anesthetics in the Development of Transient Neurologic Symptoms (TNS) Following Spinal Anesthesia: A Meta-Analysis of Randomized Controlled Trials

The use of lidocaine in spinal anesthesia may increase the risk of transient neurological symptoms (TNS) according to previous meta-analyses. However, the previous meta-analyses lacked data on some other local anesthetics and thus, more evaluations are still needed to compare the effect of lidocaine on the development of TNS. The objective of this study was to compare the risk of TNS according to lidocaine versus other local anesthetics in patients undergoing spinal anesthesia. A total of 39 randomized controlled trials with 4733 patients were analyzed. The incidence of TNS was 10.8% in the lidocaine group and was 2.2% in the control groups (risk ratio (RR) 4.12, 95% confidence interval (CI) 3.13 to 5.43, p < 0.001). In subgroup analysis, lidocaine increased the incidence of TNS compared with other local anesthetics except mepivacaine, ropivacaine or sameridine. The risk of TNS was higher in the hyperbaric (p < 0.001) or isobaric lidocaine (p < 0.001) group compared with the control group, but there were no differences found between the two groups when hypobaric lidocaine was administered (p = 1.00). This study confirmed that lidocaine for spinal anesthesia still causes TNS more frequently than most other local anesthetics, especially when hyperbaric or isobaric lidocaine was used.

Novel local anaesthetics and novel indications for local anaesthetics

Research into local anaesthetic mechanisms over the past few years has focused on two main issues. First, attention has focused on development of compounds with fewer side effects, better sensory/motor separation and longer duration of action; this has resulted in the introduction of ropivacaine and levobupivacaine into clinical practice. These agents have a lesser cardiotoxic effect than older compounds, and ropivacaine may in addition offer better sensory/motor separation. Several other compounds, including tonicaine and sameridine, are under investigation. In addition, the local anaesthetic properties of amitryptiline are being studied, and liposome encapsulation of local anaesthetics appears able to confer new pharmacokinetic properties on common drugs. Second, the molecular basis for several local anaesthetic actions that are not mediated by sodium channels has become a topic of interest. The mechanisms that underlie anti-inflammatory and antithrombotic actions are at present being unravelled. How local anaesthetics potentiate antitumour agents, protect neuronal tissue and prevent bronchial reactivity is less clear, but the potential clinical benefits of these effects deserve further exploration.