Psoriasis photochemotherapy refers to a specific treatment involving the administration of psoralen with ultraviolet A (UVA) phototherapy, which is usually shortened to PUVA phototherapy.
UVA radiation is present in sunlight and can be useful in the treatment of psoriasis due to its effect on the production of skin cells, slowing down rapid growth that plays a major role in the pathophysiology of the disease. Psoralen is a medication that can be administered orally or topically to increase the sensitivity of the patient’s skin to the light radiation and thus the effect of the therapy.
Scientific research has supported the use of PUVA in the treatment of psoriasis, finding that more than 85% of patients have a positive response to the therapy. In the majority of cases, the symptoms disappear and remission is induced, although the duration of this remission varies for different individuals and it is not able to cure the condition.
PUVA is recommended for adults in the treatment of various types of psoriasis that is moderate to severe, including:
- Plaque psoriasis
- Guttate psoriasis
- Psoriasis on the palms of hands
- Psoriasis on the soles of feet
It is not normally used for children or young adults but is sometimes necessary for patients with severe psoriasis that is not responsive to other treatments.
The administration of PUVA is quite simple and involves the following process for the optimal results of the therapy.
- Administration with psoralen, orally or topically.
- Wait for absorption and effect of psoralen to begin.
- Exposure of affected areas of skin to UVA lamps for specified time.
The time of exposure to UVA in relation to the psoralen dosing is important and should be carried out precisely for the best results. For oral administration, UVA exposure should commence 75-120 minutes after taking the pill. For topical administration, UVA exposure should commence approximately 15 minutes after application.
Similarly to UVB phototherapy, the exposure time is determined by the skin type and sensitivity to sunlight of the individual for optimal results with fewer side effects.
PUVA Adverse Effects
There are several side effects associated with the use of PUVA therapy, which include:
- Skin reddening
- Skin aging
There are some methods that may help to cope with some of these side effects. For example, administration of antihistamine medication or capsaicin extract can help to relieve itchiness. Additionally, rotating PUVA treatment with other therapies indicated for psoriasis can help to reduce the impact of side effects.
Skin Cancer Risk
There is a significantly increased risk of skin cancer with the administration of PUVA phototherapy, specifically squamous cell carcinoma and basal cell carcinoma. Scientific research has linked a greater number of PUVA treatments to a higher risk of these skin cancers.
For this reason, patients that have undergone long-term PUVA treatments should receive adequate care to monitor changes to the skin and detect early signs of skin cancer, should they present. Individuals that have had more than 150 PUVA treatments should have their skin examined by a dermatologist at least once a year.