Effectiveness and Safety of Topical Phototherapy in the Treatment of Dermatological Diseases

Abstract

Phototherapy consists in the use of ultraviolet (UV) radiation from artificial sources for therapeutic purposes. Despite the introduction of new and powerful drugs (including biological and target therapies), phototherapy remains an established, lower cost, and effective option for the treatment of many common skin diseases. In systemic photochemotherapy or PUVA, photosensitizing agents of the family of Psoralens are used in combination with UVA, i.e. with long wave ultraviolet radiation. Psoralens strongly enhance the effect of UVA alone, as they interact with biological macromolecules, causing the production of oxygen free radicals within the photoactivated cells. However, systemic administration of psoralens can be problematic, causing possible negative interactions with other drugs and the onset of serious side effects. To counteract these limitations, it has been developed the bath-PUVA therapy, which consists in the topical administration of psoralens by bathing the whole body surface in an alcoholic solution of 8-methoxypsoralen (8-MOP); immediately afterwards this pretreatment, the patient is UVA-irradiated. This technique has several advantages over conventional PUVA, including the use of a reduced UVA dosage, thus resulting in minimal skin damage with complete elimination of skin photosensitivity within three hours after the treatment; furthermore, it virtually eliminates systemic side effects and drug interference due to the very limited percutaneous absorption of psoralens. Bath-PUVA is indicated and effective in the treatment of many chronic inflammatory dermatoses (including psoriasis, atopic and allergic dermatitis, lichen ruber planus, chronic urticaria, and mastocitosis), autoimmune skin diseases (including vitiligo, and alopecia aerata), and premalignant/malignant lymphoproliferative conditions (including actinic reticulosis, parapsoriasis, and early stages of mycosis fungoides). Chronic and refractory pruritus and graft-versus-host diseases can also benefit from bath-PUVA. Another emerging PUVA technique is gel-PUVA, which is based on the application of a gel-based formulation of 8-MOP on affected skin areas , followed by UVA radiation. The formulation of 8-MOP-containing gels is conceived to increase bioavailability, limit its spread to adjacent skin and improve cosmetic aspects, while making negligible the

Anticancer Potential of Furanocoumarins: Mechanistic and Therapeutic Aspects

“…Unfortunately, it is linked toa risk of basal cell, squamous cell, and non-melanoma skin cancers [130,131]. PUVA has been approved by the FD, [132]. PUVA is ideal for superficial applications only, due to low penetration into deep tissues.…”