The maximum safe dose of lignocaine (lidocaine) without epinephrine for infiltration anaesthesia in an adult is:

• A 4.5 mg/kg
• B 7 mg/kg
• C 10 mg/kg
• D 3 mg/kg ✓

Explanation

The recommended maximum dose of plain lidocaine (without epinephrine) for infiltration and peripheral nerve block is 3–4 mg/kg in adults, with a ceiling of approximately 300 mg. When combined with epinephrine (1:200,000), the maximum dose can be increased to 7 mg/kg (up to 500 mg) because vasoconstriction slows systemic absorption and reduces peak plasma concentration. Exceeding these limits risks systemic local anaesthetic toxicity (LAST), manifesting first as CNS excitation and then cardiovascular collapse.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.