lidocaine + tetracaine: clinical use

Prescribing considerations

• Confirm that the procedure and patient age match the licence for the chosen formulation.
• Check skin integrity, application site and cumulative exposure to all local anaesthetics.
• Use caution in hepatic, renal or cardiac impairment and in acutely ill or debilitated patients.
• Avoid the cream before intradermal live vaccines; closely monitor vaccine response if the plaster was used.
• Consider methaemoglobinaemia susceptibility and interacting medicines when selecting the cream.

Contraindications and cautions

• Hypersensitivity to lidocaine, tetracaine, amide or ester local anaesthetics, para-aminobenzoic acid or relevant excipients.
• Application to mucous membranes or skin with a compromised barrier.
• For the cream, hypersensitivity to its paraben preservatives; for the plaster, hypersensitivity to sodium borate or its other excipients.

Monitoring

• Check local reactions and recovery of sensation before exposure to trauma or extreme temperatures.
• After suspected excessive exposure, observe for neurological, cardiovascular or respiratory toxicity.
• Promptly assess blue-grey discolouration, hypoxia or unexplained breathlessness for methaemoglobinaemia, particularly with the cream.

Clinical pharmacology

Both agents block voltage-gated sodium channels. Lidocaine is mainly metabolised hepatically, principally through CYP1A2 with a smaller CYP3A4 contribution; tetracaine is rapidly hydrolysed by plasma esterases. Absorption varies with exposure, skin thickness and skin condition.

Formulation and product differences

• The heat-releasing plaster is licensed for needle puncture in adults and children aged 3 years and over, and for superficial surgery in adults.
• The peel-forming cream is licensed only for adults undergoing dermatological procedures. It must be applied with a tool, and facial application should be performed by a healthcare professional.
• Paediatric use of the cream is not recommended because safety and efficacy have not been established. Use of the plaster below 3 years is strongly discouraged.

Cream

Route: Cutaneous

Strengths: 70 mg/g + 70 mg/g