lidocaine + prilocaine: clinical use

Prescribing considerations

• Confirm the indication and formulation: the cream and penile spray are not interchangeable.
• Assess the application site, skin integrity, age, atopic dermatitis, anaemia-related disorders, G6PD status, interacting medicines and previous local-anaesthetic reactions.
• Genital-mucosal and leg-ulcer use of the cream requires healthcare-professional administration or supervision.
• Investigate persistent or newly acquired premature ejaculation where an underlying physical or psychological cause may require management.
• For the spray, counsel about partner transfer, temporary hypoaesthesia, condom material and conception planning.

Contraindications and cautions

• Hypersensitivity to lidocaine, prilocaine, amide-type local anaesthetics or product excipients.
• For the spray, hypersensitivity in either the patient or partner is a contraindication.
• Do not use EMLA in preterm infants born before 37 completed weeks’ gestation or in infants up to 12 months receiving methaemoglobin-inducing medicines.
• Avoid EMLA on open wounds other than leg ulcers and on an impaired tympanic membrane.
• Exercise particular caution with G6PD deficiency, congenital or acquired methaemoglobinaemia, anaemia, atopic dermatitis and severe hepatic impairment.

Monitoring

• Routine laboratory monitoring is not generally required with correct limited topical use.
• Assess persistent local reactions, excessive numbness, erectile dysfunction or partner symptoms.
• If methaemoglobinaemia is suspected, co-oximetry is more informative than standard pulse oximetry.
• Monitor for neurological and cardiovascular local-anaesthetic toxicity after excessive exposure.
• Consider ECG monitoring when clinically significant exposure coincides with class III antiarrhythmics.

Clinical pharmacology

Both agents are amide local anaesthetics that stabilise neuronal membranes by inhibiting ion fluxes required for impulse initiation and conduction. Absorption varies with formulation, application site, skin integrity, treated area and contact time; mucosal absorption is faster than absorption through intact skin.

Formulation and product differences

• EMLA is a white topical cream for procedural anaesthesia of skin or genital mucosa and for leg-ulcer debridement; intact-skin applications generally use an occlusive dressing.
• Fortacin is a pressurised cutaneous solution applied only to the glans penis for primary premature ejaculation in adult men.
• The spray contains norflurane and is incompatible with polyurethane condoms.
• Cream exposure may be greater on mucosa, newly shaven skin, atopic skin and leg ulcers than on intact skin.

Cutaneous spray

Route: Cutaneous

Strengths: 150 mg/mL + 50 mg/mL