Local Anesthetics

 Suppress pain by blocking sodium channels, thereby blocking impulse conduction along axons  Only in neurons located near the site of administration  Suppress pain without generalized depression of nervous system

Local Anesthetics  Basic pharmacology of local anesthetics  Properties of individual local anesthetics  Clinical use of anesthetics

Basic Pharmacology of Local Anesthetics  Classification  Esters  Amides

Fig. 26–1. Structural formulas of representative local anesthetics.

Basic Pharmacology of Local Anesthetics  Mechanism of action  Suppress pain by blocking sodium channels, thereby blocking impulse conduction along axons

Basic Pharmacology of Local Anesthetics  Selectivity of anesthetic effects  Only in neurons located near the site of administration  Suppress pain without generalized depression of nervous system

Time Course of Local Anesthesia  Onset of local anesthesia  Termination of local anesthesia  Impact of regional blood flow

Basic Pharmacology of Local Anesthetics  Use with vasoconstrictors  Prolong anesthesia  Reduce the risk for toxicity—slow absorption  Fate in the body  Absorption  Distribution  Metabolism

Basic Pharmacology of Local Anesthetics  Adverse effects  CNS  Cardiovascular  Allergic reaction  Labor and delivery

Properties of Individual Local Anesthetics  Procaine  Lidocaine  Cocaine  Other local anesthetics

Procaine  Was formerly the anesthetic of choice for injection  Now replaced by others  Preparations  Available in solution (1%, 2%, and 10%)

Lidocaine  Most widely used local anesthetic  Topical and injectable applications  Effects extended if given with epinephrine  Also used for cardiac dysrhythmias

Lidocaine  Preparations  Cream  Ointment  Jelly  Solution  Aerosol  Patch

Cocaine  First local anesthetic  Central nervous system (CNS) effects  Peripheral nervous system (PNS) effects (sympathetic)  Cardiovascular effects  Preparation and administration  Should not be given with vasoconstrictor

Other Local Anesthetics  Grouped according to route  Topical  Injection

Other Local Anesthetics  Topical  Therapeutic uses  Systemic toxicity  Injection  Infiltration, nerve block, IV regional, epidural, and spinal (subarachnoid)  Should be administered by anesthesiologist  IV and monitoring required