Methyl aminolevulinate is a prodrug that is metabolised to Protoporphyrin IX (a photosensitizer) used in photodynamic therapy. 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. Methyl aminolevulinate is used 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).

Phenyl salicylate belongs to the family of hydroxybenzoic acid derivatives. Phenyl salicylate is used as a food additive. Antimycobacterial activity of phenyl salicylates (salols) was studied in connection with antituberculotic activity of salicylic derivatives. Phenyl salicylates are esters. Phenyl salicylates (salols) represent a new group of antimycobacterial compounds. Phenyl salicylate is included in the number of medications, indicated for the treatment of symptoms of irritative voiding, used to relieve the discomfort, pain, frequent urge to urinate, and cramps/spasms of the urinary tract caused by an infection or a medical procedure. Phenyl salicylate works as a pain reliever in these combinations.

Potassium salicylate is the potassium salt of salicylic acid. Potassium Salicylate is a cosmetic biocide and preservative, not currently in use. Potassium salicylate was used for the treatment of melasma. Potassium salicylate is considered safe as used when formulated to avoid irritation and when formulated to avoid increasing sun sensitivity, or, when increased sun sensitivity would be expected, directions for use include the daily use of sun protection.