Photochemotherapy

Photosensitizer

The photosensitizers used in photochemotherapy include 8-methoxypsoralen and 3-methyl psoralen, and other traditional Chinese medicines such as white peony and oxtail live extract. The most commonly used in the country is 8-methoxy psoralen internal medicine, the dose is calculated according to 0.5~0.6 mg per kg body weight, and phototherapy is performed 2 hours after taking the medicine. Can also be soaked in a water bath, usually with trimethyl psoralen 40 ~ 50 mg, dissolved in bath water, soaked for 15 ~ 20 minutes; for a small range of damage, 0.1% ~ 0.5% 8-methoxy psoralen Or topical application of trimethyl psoralen alcohol solution, phototherapy 1 to 2 hours after application.

Phototherapy method

Irradiation dose

Phototherapy is the use of long-wave ultraviolet (UVA, light wavelengths of 320 ~ 400 nm), also known as black light. The dose should be determined according to the depth of the skin pigment and the sensitivity to light, generally to achieve a mild skin phototoxic reaction or matt toxicity reaction, every other day or once a day, during the treatment, due to the skin The color gradually deepens and the light sensitivity gradually decreases, so the dose should be gradually increased.

2. Precautions

After treatment, patients should take care to avoid sun exposure to avoid aggravating skin reactions. Patients treated with oral photosensitizer should wear appropriate goggles at least 12 hours after taking the drug.

Indication

Psoriasis vulgaris

A large number of clinical data have proved that photochemotherapy has a good effect on the treatment of psoriasis vulgaris. The complete regression rate of rash is more than 80%~90%, and the regression period of rash is more than 2~4 weeks. For example, photochemotherapy (PUVA) combined with retinoic acid treatment is more effective. Photochemotherapy is mainly for patients with psoriasis vulgaris and psoriasis psoriasis who are not cured for a long time and who are ineffective in general treatment or have serious side effects and cannot continue treatment.

2. erythrodermic psoriasis

The treatment with PUVA is also satisfactory. This type of psoriasis is treated with PUVA in combination with etretinate, and the effect is better. It is best to take oral etretinate for about 10 days, plus photochemotherapy, which can reduce the accumulation of long-wave UV. Do not pay attention to the initial dose of long-wave UV, the amount should be slow to prevent the symptoms of erythroderosis.

3. Pustular psoriasis

Photochemotherapy is also often effective, and some patients who have long been treated with corticosteroids or cytokine inhibitors often have improved conditions after treatment with PUVA. Corticosteroids and cytostatics can also be gradually reduced to discontinuation, but the treatment time is longer, and the cumulative amount of long-wave ultraviolet light per unit area is also large.

For the above types of psoriasis after PUVA treatment, how to prevent recurrence, some people have advocated to continue the consolidation treatment after the skin lesions subsided, but some reports prove that patients with consolidation treatment, the recurrence rate is no better than no consolidation The treated patients were significantly reduced, and the remission period was not extended, and the consolidation treatment would increase the cumulative amount of long-wave ultraviolet rays per unit area, so it is not recommended at present.