Spinal Anesthesia: A Comprehensive Review of Intrathecal Local Anesthetics and Adjuvant Agents

Abstract

Spinal anesthesia is a widely used neuraxial technique that provides effective surgical anesthesia and postoperative analgesia while avoiding many of the adverse effects associated with general anesthesia. Selection of an appropriate intrathecal agent is essential for achieving a rapid and reliable sensory and motor block while allowing predictable recovery with minimal adverse effects. Local anesthetics used for spinal anesthesia differ considerably in their pharmacological characteristics including onset, duration of action, baricity, and safety profile. Short-acting agents such as chloroprocaine and lidocaine facilitate rapid recovery, whereas intermediate-acting agents such as mepivacaine and ropivacaine provide a balance between block duration and postoperative mobilization. Long-acting agents including bupivacaine and levobupivacaine, provide prolonged and predictable anesthesia for longer surgical procedures. Furthermore, intrathecal adjuvants including opioids, α2-adrenergic agonists, ketamine, magnesium sulfate, and nalbuphine may enhance block quality, prolong analgesia, and reduce local anesthetic requirements, although their potential adverse effects should be considered. Understanding the available drug options and their pharmacological properties is therefore essential for tailoring spinal anesthesia to the individual patient and surgical procedure.