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Local anaesthetic (amide class) Pregnancy: Generally safe for local infiltration at correct doses.

Lidocaine / Mepivacaine (Local Infiltration — Plastics)

Brand names: Xylocaine (lidocaine), Scandonest (mepivacaine)

Adult dose

Dose: Lidocaine plain: max 3 mg/kg; with adrenaline: max 7 mg/kg
Route: Local infiltration or nerve block
Frequency: Single procedure dose
Max: Lidocaine plain: 200 mg; with adrenaline (1:200,000): 500 mg
Wound repair/minor plastics: lidocaine 1% (10 mg/mL). Max 3 mg/kg plain, 7 mg/kg with adrenaline. Add sodium bicarbonate 8.4% (1 mL per 10 mL lidocaine) to reduce injection pain. NEVER use adrenaline-containing solutions in fingers, toes, nose, ear, penis (terminal arteries — necrosis risk).

Paediatric dose

Dose: 3 mg/kg
Route: Local infiltration
Frequency: Single dose
Max: 3 mg/kg plain; 7 mg/kg with adrenaline
Concentration: 10 mg/ml
Children: max 3 mg/kg (plain) or 7 mg/kg (with adrenaline). Calculate total dose in mg. For example, 1% lidocaine (10 mg/mL): 3 mg/kg ÷ 10 mg/mL = 0.3 mL/kg (max volume). Buffered with NaHCO3 for less painful infiltration.

Dose adjustments

Renal

No dose adjustment for local infiltration.

Hepatic

Caution with large doses in severe hepatic impairment (reduced metabolism).

Paediatric weight-based calculator

Children: max 3 mg/kg (plain) or 7 mg/kg (with adrenaline). Calculate total dose in mg. For example, 1% lidocaine (10 mg/mL): 3 mg/kg ÷ 10 mg/mL = 0.3 mL/kg (max volume). Buffered with NaHCO3 for less painful infiltration.

Clinical pearls

  • Never use adrenaline-containing LA in 'end arteries' (digits, nose, ear, penis) — ischaemia
  • Reduce injection pain: warm LA to body temperature, use fine needle, inject slowly
  • Aspirate before injecting (avoids intravascular injection)
  • LAST (Local Anaesthetic Systemic Toxicity): treat with Intralipid 20% if toxicity signs (lipid rescue)
  • Tumescent technique: dilute LA in large volumes saline for liposuction — total dose higher but safe due to slow absorption

Contraindications

  • Amide LA allergy (rare)
  • Injection into infected tissue (reduces efficacy)
  • Adrenaline-containing LA in digital/penile/nasal/auricular blocks

Side effects

  • CNS toxicity (perioral tingling → seizures → cardiac arrest — dose-related)
  • Cardiovascular toxicity (hypotension, arrhythmias — dose-related)
  • Adrenaline effects (tachycardia, hypertension) if large doses absorbed
  • Haematoma at injection site

Interactions

  • Beta-blockers — may enhance hypotension
  • MAOIs — hypertensive risk with adrenaline component

Monitoring

  • CNS symptoms (tingling, confusion)
  • Heart rate and BP
  • Total dose calculation

Reference: BNFc; BNF; AAGBI Local Anaesthetic Toxicity Guidelines; BNFc. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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