Pharmacology
Mechanism of Action
Methyl aminolevulinate (prodrug) is metabolically converted to photoactive porphyrins (PAPs), which accumulate in the skin lesions resulting in photosensitization. When exposed to light of appropriate wavelength and energy, the accumulated PAPs produce a photodynamic reaction, releasing oxygen singlets which result in local cytotoxicity.
Use: Labeled Indications
Metvixia [DSC]: Actinic keratosis: Conventional photodynamic therapy (c-PDT) to be used in conjunction with red light illumination for the treatment of thin and moderately thick, nonhyperkeratotic, nonpigmented actinic keratoses of the face and scalp in immunocompetent patients.
Limitations of use: Safety and efficacy have not been established for treatment of cutaneous malignancies or for skin lesions other than nonhyperkeratotic face and scalp actinic keratoses using PDT with methyl aminolevulinate cream; safety and efficacy of methyl aminolevulinate cream have not been established in patients with immunosuppression, porphyria, or pigmented actinic keratosis; has not been tested on patients with inherited or acquired coagulation defects; use without subsequent red light illumination is not recommended.
Metvix [Canadian product]:
Actinic keratosis: c-PDT to be used in conjunction with red light illumination or as daylight-photodynamic therapy (DL-PDT) for the treatment of thin or nonhyperkeratotic and nonpigmented actinic keratosis of the face and scalp when other therapies are less appropriate.
Basal cell carcinoma: c-PDT to be used in conjunction with red light illumination for the treatment of biopsy-confirmed primary superficial basal cell carcinoma outside the H-zone of the face (eg, ears and nose) when other therapies are less appropriate.
Contraindications
Known sensitivity to methyl aminolevulinate or any component of the formulation, including peanut and almond oil (has not been tested in patients with peanut allergy); individuals with cutaneous photosensitivity; allergy to porphyrins
Canadian labeling: Additional contraindications (not in US labeling): Morpheaform basal cell carcinoma.
Dosage and Administration
Dosing: Adult
Metvixia [DSC]: Actinic keratoses: Topical: Apply up to 1 g to prepared actinic keratoses, occlude for 3 hours, followed by red light illumination; repeat in 1 week. Note: If multiple lesions being treated, 1 g should not be exceeded for all lesions combined per treatment session.
Metvix c-PDT [Canadian product]:
Actinic keratosis (thin or nonhyperkeratotic and nonpigmented): Topical: Apply up to a maximum of 2 g for all lesions combined per treatment session, occlude treated lesions for 3 hours, followed by red light illumination. Assess patient after 3 months and if needed may administer one additional treatment session. Use without subsequent red light illumination is not recommended.
Basal cell carcinoma (superficial): Topical: Apply up to a maximum of 2 g for all lesions combined per treatment session, occlude treated lesions for 3 hours, followed by red light illumination. Repeat in 1 week. Following second treatment session, assess patient after 3 months and if needed may administer up to 2 additional treatment sessions (separated by 1 week). Use without subsequent red light illumination is not recommended.
Metvix DL-PDT [Canadian product]: Actinic keratosis (thin or nonhyperkeratotic and nonpigmented): Topical: Apply up to a maximum of 2 g for all lesions combined per treatment session, followed by daylight exposure (no occlusion is recommended). Assess patient after 3 months and if needed may administer one additional treatment session.
Dosing: Geriatric
Refer to adult dosing.
Administration
Prepare lesions using a small dermal curette to remove scales and crusts and roughen the surface of the lesion. Wearing nitrile gloves (latex and vinyl gloves do not provide enough protection) and using a spatula, apply a layer of methyl aminolevulinate cream about 1 mm thick topically to prepared lesion and the surrounding 5 mm of normal skin. Multiple lesions may be treated during the same treatment session; do not exceed a treatment field area of 80 x 180 mm. Do not exceed a total of 1 g of Metvixia cream or 2 g Metvix cream [Canadian product] per treatment session.
When used in conjunction with c-PDTL: Occlude the site(s) with a nonabsorbent dressing for 3 hours (minimum 2.5 hours, maximum 4 hours), then remove. Remove excess cream with saline and illuminate with red light following lamp manufacturer's instructions. Following illumination of site, the treated area should be kept covered and away from bright indoor light and sunlight from 48 hours. If red light treatment is interrupted or stopped it may be restarted. However, if for any reason, red light illumination is not done, the cream should be removed within 3 hours (from time of initial application) and the area protected from sunlight or prolonged/intense light for 48 hours. Use in conjunction with Atkilite CL 128 lamp.
When used in conjunction with DL-PDT: Metvix [Canadian product]: Prior to preparing the lesions, sunscreen (≥ SPF 30), that does not include filters which may inhibit absorption of visible light (eg, titanium dioxide, zinc oxide, iron oxide), should be applied to all sun exposed areas including the treatment areas. Occlusion of the treatment site(s) is not necessary. Patients should go outside immediately after therapy or within 30 minutes; remain in daylight for 2 continuous hours, then remove cream with soap and water.
Storage
Store at 2°C to 8°C (36°F to 46°F). Use contents within 1 week after opening; discard if unrefrigerated for >24 hours.
Drug Interactions
There are no known significant interactions.
Adverse Reactions
Pain and burning begin during illumination and generally resolve completely within a few minutes or hours, but may last up to a few days. Erythema and other signs generally resolve within a few days up to 3 weeks.
>10%:
Central nervous system: Local discomfort (≤86%; severe: ≤20%)
Dermatologic: Burning sensation of skin (≤86%; severe: ≤20%), skin pain (≤86%; severe: ≤20%), erythema (63%; severe 6%), crusted skin (≤29%), skin blister (≤29%), skin erosion (≤29%), pruritus (22%), exfoliation of skin (14%)
Local: Skin edema (≤18%)
Ophthalmic: Eyelid edema (≤18%)
1% to 10%:
Central nervous system: Localized warm feeling (4%)
Dermatologic: Dermal hemorrhage (2%), hyperpigmentation (2%), skin tightness (2%)
Local: Application site discharge (2%)
<1%, postmarketing, and/or case reports: Angioedema, contact dermatitis, eczema, facial edema, infection (application site), keratitis, macular edema, squamous cell carcinoma of skin, urticaria, vitreous detachment
Warnings/Precautions
Concerns related to adverse effects:
- Photosensitivity: Treatment sites will become photosensitive and should be protected from sunlight or bright indoor light (eg, examination lamps, operating room lamps, tanning beds, or lights at close proximity) and protected from extreme cold with adequate clothing or by remaining indoors between application of cream and red light illumination and for 48 hours after treatment. Sunscreens will not protect against photosensitivity reactions caused by visible light. After illumination, treated sites should be kept covered and away from light for at least 48 hours.
Disease-related concerns:
- Coagulation defects: Has not been tested on individuals with coagulation defects (acquired or inherited).
- Immune deficiency: Has not been tested on patients with immunosuppression.
- Pigmented actinic keratosis: Has not been tested on patients with pigmented keratosis.
- Porphyria: Has not been tested on patients with porphyria.
Concurrent drug therapy issues:
- Photosensitizing agents: Concomitant use of other known photosensitizing agents may increase the degree of photosensitivity reaction.
Other warnings/precautions:
- Appropriate use: For external use only. Do not apply to eyes or mucous membranes. Should be applied by a qualified health professional. Has not been studied for >1 course of treatment (2 application sessions separated by 1 week). Assess lesion response 3 months after the last treatment session.
Pregnancy
Pregnancy Risk Factor
C
Pregnancy Considerations
Animal reproduction studies have not been conducted with methyl aminolevulinate cream.
Patient Education
What is this drug used for?
- It is used to treat a precancerous skin problem called actinic keratosis.
Frequently reported side effects of this drug
- Headache
- Application site bleeding, blisters, burning, crusting, itching, pain, peeling, redness, stinging, swelling, or ulcers
Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:
- Severe or persistent skin reaction
- Bruising
- Bleeding
- Signs of a significant reaction like wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat.
Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.
Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.
