Insignificant systemic exposure. No phototoxic effects outside the skin application site.

Methyl aminolevulinate is a linear metylated five carbon molecule. After tissue demetylation it constitutes the initial precursor in porphyrin biosynthesis.

Methyl aminolevulinate hydrochloride is a derivative of 5-aminolevulinic acid that is applied topically for the treatment of non-hyperkeratotic, non-pigmented actinic keratoses of the face or scalp, and in the treatment of superficial and/or nodular basal cell carcinoma.

Not significant.

Metabolized in situ to phototoxic porphyrins. In-vitro studies of dermal absorption found that the mean cumulative absorption of methyl aminolevulinate through healthy human skin after 24 hours was 0.26% of a dose.