Indication |
For topical use, in combination with 570 to 670 nm wavelength red
light illumination, in the treatment of non-hyperkeratotic actinic
keratoses of the face and scalp in immunocompetent patients when used in
conjunction with lesion preparation (debridement using a sharp dermal
curette). |
Pharmacodynamics |
After topical application of methyl aminolevulinate, porphyrins
will accumulate intracellularly in the treated skin lesions. The
intracellular porphyrins (including PpIX) are photoactive, fluorescing
compounds and, upon light activation in the presence of oxygen, singlet
oxygen is formed which causes damage to cellular compartments, in
particular the mitochondria. Light activation of accumulated porphyrins
leads to a photochemical reaction and thereby phototoxicity to the
light-exposed target cells. |
Mechanism of action |
Photosensitization following application of methyl aminolevulinate
cream occurs through the metabolic conversion of methyl aminolevulinate
(prodrug) to photoactive porphyrins (PAP), which accumulates in the
skin lesions to which the cream has been applied. When exposed to light
of appropriate wavelength and energy, the accumulated photoactive
porphyrins produce a photodynamic reaction, resulting in a cytotoxic
process dependent upon the simultaneous presence of oxygen. The
absorption of light results in an excited state of porphyrin molecules,
and subsequent spin transfer from photoactive porphyrins to molecular
oxygen generates singlet oxygen, which can further react to form
superoxide and hydroxyl radicals. |
Absorption |
In vitro, after 24 hours the mean cumulative absorption through human skin was 0.26% of the administered dose. |
Volume of distribution |
Not Available |
Protein binding |
Not Available |
Metabolism |
Not Available |
Route of elimination |
Not Available |
Half life |
Not Available |
Clearance |
Not Available |
Toxicity |
The severity of local phototoxic reactions such as erythema, pain
and burning sensation may increase in case of prolonged application time
or very high light intensity. |