lidocaine: clinical use

Prescribing considerations

• Match the formulation to its licensed indication and intended skin site.
• Consider total exposure from all lidocaine and other local-anaesthetic products.
• Avoid damaged or inflamed skin; absorption rises with larger treated areas, prolonged exposure and impaired skin barriers.
• Use the plaster cautiously in severe cardiac, renal or hepatic impairment; severe hepatic disease can also increase toxicity risk with cream.
• Periodically confirm that continued plaster treatment provides meaningful benefit.

Contraindications and cautions

• Hypersensitivity to lidocaine, formulation excipients or other amide local anaesthetics.
• Medicated plaster application to inflamed or injured skin, active shingles lesions, atopic dermatitis or wounds.
• LMX4 application to irritated skin, raw or extensively damaged areas, or where migration into the middle ear is possible.

Monitoring

• Assess local skin reactions and integrity at application sites.
• Review for neurological or cardiovascular toxicity if exposure may be excessive.
• Consider ECG monitoring when LMX4 is used with amiodarone.
• Review efficacy and continuing need during longer-term plaster treatment.

Clinical pharmacology

Lidocaine reversibly stabilises neuronal membranes through voltage-gated sodium-channel blockade. Cutaneous absorption depends on formulation, application area, duration and skin integrity; absorbed lidocaine is predominantly metabolised in the liver.

Formulation and product differences

• LMX4 is a cream for temporary surface anaesthesia of intact skin before specified procedures.
• The medicated plaster delivers lidocaine locally for adult post-herpetic neuralgia and provides mechanical protection to hypersensitive skin.
• LMX4 contains propylene glycol and benzyl alcohol; the plaster contains propylene glycol and parabens, which may cause local or delayed reactions.

Cream

Route: Cutaneous

Strengths: 4% w/w