Lidocaine

Local anesthetic for nerve blocks and infiltration in horses and small animals; IV antiarrhythmic for ventricular tachyarrhythmias; GI prokinetic CRI in horses. Amide-type local anesthetic and antiarrhythmic (lidocaine HCl). Mechanism: reversibly blocks voltage-gated sodium channels → prevents axon depolarization and nerve impulse conduction (local anesthetic). As antiarrhythmic (Class IB): preferentially blocks activated/inactivated Na+ channels in ventricular myocardium → suppresses premature ventricular contractions. IV CRI in horses: enhances GI prokinesis via ENS modulation. Key information Antiarrhythmic/local anesthetic. Rapid IV bolus can cause seizures, hypotension, cardiac arrest — infuse slowly or dilute. Narrow therapeutic index. Topical (EMLA): eutectic mixture, apply 45–60 min before procedure. Do NOT use lidocaine with epinephrine for ring blocks on digits/tail (vasoconstriction causes ischemia).

Injectable local anesthetic: infiltrate SQ/perineural at target site; aspirate before injection. IV (antiarrhythmic/prokinetic, horses): dilute; administer loading dose over 5–10 min then CRI. Do not use formulations with epinephrine for IV use. Topical gel/solution: apply to mucosal surfaces or catheter insertion sites. Store at room temperature; protect from light. If a dose is missed This medication is administered by a veterinarian or veterinary staff in a clinical setting. Missed doses are managed by your veterinary team — contact your veterinarian to reschedule.

CNS toxicity (intravascular injection or overdose): tremors, seizures, respiratory arrest. Cardiovascular: hypotension, bradycardia, AV block, VF (high serum levels). Methemoglobinemia (very rare). Tissue myopathy (local injection — especially in horses). Horses/cats: sensitive to CNS toxicity at lower doses.

For animals Avoid rapid IV bolus in cats (severe CNS and cardiovascular toxicity at lower doses than dogs). Horses and cats: sensitive to CNS toxicity — use lower doses and monitor closely. Do not use epinephrine-containing solutions in extremities, ears, or penis. IV CRI: monitor ECG for arrhythmias. Drug interaction: cimetidine and beta-blockers increase lidocaine levels. For people handling this medication Wear gloves when handling. Wash hands thoroughly with soap and water after handling. Local anesthetic — if accidentally self-injected, seek emergency medical attention (cardiovascular toxicity). Avoid getting topical or gel forms in your own mouth. Keep out of reach of children.

This is a veterinary emergency. Overdose causes cardiac arrhythmias and seizures. Immediate veterinary intervention required — supportive care including IV lipid emulsion therapy may be needed.