METVIX

What it is

Metvix is a cream containing 160 mg/g of methyl aminolevulinate (as hydrochloride). Methyl aminolevulinate is an antineoplastic agent. After topical application, porphyrins accumulate intracellularly in treated skin lesions. Upon light activation in the presence of oxygen, these photoactive porphyrins generate singlet oxygen which causes damage to cellular compartments, particularly the mitochondria, leading to phototoxicity in light-exposed target cells.

Approved indications

— Treatment of thin or non-hyperkeratotic and non-pigmented actinic keratoses on the face and scalp when other registered therapies are unacceptable. — Primary treatment of superficial and/or nodular basal cell carcinoma where surgery is considered inappropriate. — Treatment of biopsy-proven squamous cell carcinoma in situ (Bowen's disease), where surgery is considered inappropriate. Metvix is indicated in adults above 18 years of age.

Dosing overview

For treatment of actinic keratoses, one session of photodynamic therapy (PDT) should be administered with either red LED light via a suitable lamp (c-PDT) or exposure to natural daylight (DL-PDT). For treatment of basal cell carcinoma and squamous cell carcinoma in situ (Bowen's disease), two sessions of c-PDT should be administered with an interval of one week between sessions. Metvix should be applied as a layer about 1 mm thick to the lesion and surrounding 5–10 mm of normal skin, covered with an occlusive dressing for 3 hours, then exposed to red light with a continuous spectrum of 570–670 nm and a total light dose of 75 J/cm², or an LED light source with an average wavelength of 630 nm and a light dosage of 37 J/cm². Treated lesions should be assessed after three months and those with non-complete response should be retreated, as per the initial treatment method.

Key safety warnings

Methyl aminolevulinate may cause sensitisation by skin contact resulting in angioedema, application site eczema or allergic contact dermatitis. Direct eye contact should be avoided, and Metvix cream should not be applied to the eyelids and mucous membranes. Between 60% and 80% of patients using conventional photodynamic therapy experienced treatment-site reactions attributable to phototoxicity or lesion preparation. The most frequent symptoms are painful and burning skin sensation typically beginning during illumination or soon after and lasting for a few hours with resolution on the day of treatment. The most frequent signs of phototoxicity are erythema and oedema which may persist for 1 to 2 weeks or occasionally for longer; in two cases they persisted for more than one year. In patients with a history of hypertension, pain during illumination may induce increased blood pressure. Blood pressure should be measured in these patients who experience severe pain, and illumination should be interrupted if severe hypertension develops. Conventional photodynamic therapy with a red-light lamp may rarely precipitate transient global amnesia, with stress and pain associated with illumination increasing the risk. If signs of confusion or disorientation are observed, PDT must be discontinued immediately.

Contraindications

Metvix is contraindicated in hypersensitivity to the active substance or to any of the excipients including arachis oil (peanut oil); morpheaform basal cell carcinoma; invasive squamous cell carcinoma of the skin; and porphyria.

PBS listing

No PBS listing information is contained in the provided source documents.

Regulatory history

Metvix (methyl aminolevulinate 160 mg/g cream) was first registered on the ARTG on 4 April 2003. The date of first approval was 5 July 2003.