Local anesthetic

A local anesthetic (LA) is a medication that causes absence of all sensation (including pain) in a specific body part without loss of consciousness, as opposed to a general anesthetic, which eliminates all sensation in the entire body and causes unconsciousness. Local anesthetics are most commonly used to eliminate pain during or after surgery. When it is used on specific nerve pathways (local anesthetic nerve block), paralysis (loss of muscle function) also can be induced. LAs are of 2 types: Clinical LAs: amino amide LAs amino ester LAs Synthetic LAs Cocaine derivatives Synthetic cocaine-derived LAs differ from cocaine because they have a much lower abuse potential and do not cause hypertension vasoconstriction (with few exceptions). The suffix "-caine" at the ends of these medication names is derived from the word "cocaine", because cocaine was formerly used as a local anesthetic. Short Duration of Action and Low Potency Benzocaine Procaine Chloroprocaine Medium Duration of Action and Medium Potency Lidocaine Prilocaine High Duration and High Potency Tetracaine Bupivacaine Cinchocaine Ropivacaine Local anesthetics may be used to prevent and/or treat acute pain, to treat chronic pain, and as a supplement to general anesthesia. They are used in various techniques of local anesthesia such as: Topical anesthesia (surface anesthesia) Topical administration of cream, gel, ointment, liquid, or spray of anesthetic dissolved in DMSO or other solvents/carriers for deeper absorption Infiltration Brachial plexus block Epidural block (extradural) Spinal anesthesia (subarachnoid block) Iontophoresis Diagnostic purposes (e.g. dibucaine) Anti-arrhythmic agents (e.g. lidocaine). Even though acute pain can be managed using analgesics, conduction anesthesia may be preferable because of superior pain control and fewer side effects. For purposes of pain therapy, LA drugs are often given by repeated injection or continuous infusion through a catheter. LA drugs are also often combined with other agents such as opioids for synergistic analgesic action.