8MOP

8-MOP, also known as methoxsalen or 8-methoxypsoralen, is a psoralen derivative used as a photosensitizing agent in PUVA therapy. It belongs to the furocoumarin family and is employed to enhance the effects of ultraviolet A (UVA) light in treating certain skin disorders.

Mechanism and use

When exposed to UVA radiation, 8-MOP intercalates into DNA and, upon irradiation, forms covalent bonds with pyrimidine bases. This photochemical reaction increases the sensitivity of skin cells to UVA, promoting controlled cell growth inhibition and apoptosis in hyperproliferative or inflammatory skin conditions. Clinically, 8-MOP is used in photochemotherapy to treat psoriasis, eczema (atopic dermatitis), and vitiligo, among other conditions. It can be administered orally or applied topically as part of a bath-PUVA or topical PUVA regimen, depending on the condition and clinician preference.

Administration and dosing

Dosing is determined by formulation, body weight, and treatment protocol, and must be supervised by a healthcare professional. Oral administration is typically timed before UVA exposure, while topical formulations are applied to affected areas prior to UVA irradiation. In clinical practice, UVA exposure is carefully controlled to balance therapeutic benefit with the risk of adverse effects.

Safety and adverse effects

Common adverse effects include phototoxic reactions such as rash or sunburn in treated areas. Long-term PUVA therapy carries risks including photoaging, increased skin cancer risk, and cataracts with repeated UVA exposure. 8-MOP is a prescription medicine and is contraindicated in certain populations, including pregnancy, without medical supervision. Patients undergo monitoring for skin response and potential adverse effects during treatment.

See also

PUVA therapy; psoralen derivatives; photochemotherapy.