Mepivacaine is an amino amide local anesthetic used primarily for regional anesthesia and sympathetic blockade. Compared to lidocaine, mepivacaine offers a slightly longer duration of action and does not cause vasodilation. However, at high plasma levels, mepivacaine can induce uterine vasoconstriction, reducing uterine blood flow, which necessitates cautious use in obstetric applications. Mepivacaine is metabolized in the liver and is particularly noted for its application in epidural and brachial plexus blocks, as well as caudal blocks, where it is important to avoid solutions with preservatives.
The maximum single dose of mepivacaine without a vasoconstrictor ranges from 4.5 to 5 mg/kg, and should not exceed 400 mg per dose, with a daily maximum of 1000 mg within 24 hours. When combined with a vasoconstrictor such as epinephrine, the maximum dose can be increased to 7 mg/kg (some sources cite 6.6 mg/kg), not exceeding 500 mg per dose.
In the app: the Master Anesthesia app's Local Anesthetic calculator (Calculators, then Local) does this arithmetic for you, converting each agent's per-kilogram ceiling, with or without epinephrine, into a maximum dose and volume for your patient's weight and chosen concentration. Read about the Local Anesthetic dose calculator.
In brachial plexus blocks for adults, doses range from 300-750 mg using 1.0-1.5% solutions, and pediatric doses are between 0.5 – 0.75 mL/kg. High doses exceeding 4 mg/kg should include epinephrine to minimize systemic toxicity. Adding morphine, fentanyl, or tetracaine can prolong the blockade effect. For caudal blocks, the adult dose ranges from 150-400 mg with a solution concentration of 1.0-2.0%, and pediatric dosing adjusts based on the desired spinal level.
For epidural blockade, doses ranging from 150 to 400 mg, using a 1-2% solution, should be administered without preservatives. The onset and effectiveness can be improved by adding carbonation; specifically, by mixing 1 mL of 8.4% sodium bicarbonate with 10 mL of 1-3% mepivacaine. Mepivacaine's onset for epidural administration occurs within 5-15 minutes, peaking at 15-45 minutes, and generally lasts 3-5 hours, extendable with the use of epinephrine. For epidural motor blockade, reversal can be achieved by injecting 20 mL of 0.9% saline.
Drug interactions include reduced clearance of mepivacaine with beta-blockers and cimetidine. Vasoconstrictors like epinephrine and alpha-2 agonists like clonidine prolong the anesthesia.
Transient neurologic symptoms (TNS) associated with mepivacaine were a notable concern particularly with the use of hyperbaric 4% solutions, now unavailable in the U.S. This concern has been moderated by newer formulations and methods reducing the incidence of these symptoms, which include lower back, buttock, and lower extremity pain post-anesthesia. Storage of mepivacaine should be at room temperature, away from light. Absolute contraindications include known allergies to amide local anesthetics. Relative contraindications involve caution in use with OB patients due to placental crossing, and those with severe cardiac arrhythmias or heart blocks. Mepivacaine's utility in clinical practice remains significant due to its efficacy and manageability under careful monitoring and appropriate dosing strategies.
| Agent | Without epinephrine | With epinephrine |
|---|---|---|
| Bupivacaine | 2 mg/kg | 3 mg/kg |
| Ropivacaine | 3 mg/kg | 3 mg/kg |
| Lidocaine | 4.5 mg/kg, not to exceed 300 mg | 7 mg/kg, not to exceed 500 mg |
| Mepivacaine | 4.5–5 mg/kg, not to exceed 400 mg per dose (1,000 mg/24 h) | 7 mg/kg, not to exceed 500 mg per dose |
