Mepivacain

Mepivacain, also spelled mepivacaine, is an amide-type local anesthetic used to produce regional anesthesia. It is supplied in solutions for infiltration and nerve blocks and in formulations for epidural administration. Available concentrations include approximately 2% and 3%, with or without a vasoconstrictor such as epinephrine. It is used in dentistry, minor surgical procedures, and regional anesthesia techniques.

Mechanism and effects: Mepivacain works by blocking voltage-gated sodium channels on neurons, preventing action potential propagation and producing loss of sensation in the targeted area. Onset can occur within a few minutes, depending on the route and concentration; nerve blocks may take longer than surface infiltration. Adding epinephrine prolongs the duration of anesthesia and reduces systemic absorption, enabling higher doses with lower peak plasma levels.

Pharmacokinetics and dosing: Mepivacain is primarily metabolized in the liver by amidases and excreted in the urine. In individuals with normal liver function, the elimination half-life is roughly 1.5 to 2.5 hours. Maximum recommended doses vary by preparation and presence of vasoconstrictor; commonly cited ranges are about 4–5 mg/kg for plain solution and up to about 7 mg/kg with epinephrine, with absolute per-procedure limits around 400–500 mg in adults. Dosing must be adjusted for hepatic impairment, pregnancy, pediatric patients, and specific clinical contexts.

Adverse effects: At high plasma concentrations, CNS symptoms such as tinnitus, perioral numbness, dizziness, and seizures can occur, followed by cardiovascular toxicity including hypotension, arrhythmias, and potential cardiac arrest. Local reactions or hypersensitivity are possible but uncommon. Care is taken to avoid intravascular injection and to monitor for signs of systemic toxicity.

See also: Local anesthetic, Amide-type local anesthetic.