An overview of phototherapy for psoriasis

An overview of phototherapy for psoriasis
An overview of phototherapy for psoriasis

Ultraviolet light therapy is effective for many patients with psoriasis, according to a presentation by Henry W. Lim, MD, during the recent 2014 American Academy of Dermatology Annual Meeting.

Lim, Chairman and C.S. Livingood Chair of the Department of Dermatology at Henry Ford Hospital in Detroit, reviewed the application of ultraviolet-based therapy for psoriasis, described the side effects of UV therapy and explained how to select the appropriate patient for UV-based therapy.

UV-based therapy options include narrowband ultraviolet B (NB-UVB), targeted phototherapy, and psoralen and UVA Light Therapy (PUVA), also known as photochemotherapy.

NB-UVB

Patients with psoriasis who are treated with NB-UVB should have noticeable improvement within 20 to 30 treatments, according to Lim. Once optimal improvement has been achieved, treatment can be tapered to twice weekly for 4 weeks, and once weekly for 4 weeks until treatment can be discontinued. Once weekly regimen can be used for maintenance therapy.

Lim cited data from a 2012 study of healthy adults in Finland with the same baseline levels of vitamin D levels, who were treated with either NB-UVB or oral vitamin D3. Patients in the NB-UVB group received treatment three times per week for 4 weeks and patients in the oral vitamin D3 group received 20 mcg (800 IU/d) for 4 weeks.

Those treated with NB-UVB had a 41.0 nmol/L mean increase in 25-Hydroxyvitamin D levels compared with a mean increase of 20.2 nmol/L with the oral vitamin D3.

“A short course of NB-UVB effective way of increasing vitamin D levels in the winter,” Lim said.

Side effects of this treatment can include a slight increase in the risk for basal cell carcinoma for patients treated with both NB-UVB and PUVA.

Targeted phototherapy

Studies of targeted phototherapy with a 308-nm Excimer Laser have also demonstrated positive results as a psoriasis treatment.

In a 2002 study that involved 92 patients with psoriasis, 72% of patients had more than 75% clearing of lesions after six treatments, and 50% of patients had a more than 90% clearing with 10 or less treatments.

Noticeable improvement typically occurs with six to 10 treatments, Lim said. Therapy should be discontinued after 15 to 20 treatments, without tapering.

This therapy is ideal for patients with less than 10% body surface area involvement, Lim noted. However, it is problematic for use on areas of the face. Other drawbacks include expense, as insurance may not cover the treatment.

PUVA

PUVA, a type of phototherapy that combines the use of ultraviolet A (UVA) light therapy and a psoralen medication, typically yields noticeable improvements in psoriasis within 20 to 30 treatments.

Initial dosing begins at 0.5 J/cm2, with incremental dosing amounts and the maximum dose determined based on skin type 1-6. Once optimal improvement has been achieved, treatment should be tapered to twice weekly for 4 weeks, and once weekly for 4 weeks and then discontinued.

The dose should be held at once weekly regimen, Lim said.  He spoke specifically about Oxsoralen Ultra (Valeant Pharmaceuticals International), a liquid formulation of 8-methoxypsoralen (8-MOP) 0.5 mg to 0.6 mg/kg given 1 hour prior to UVA.

Treatment with Oxsoralen should not exceed 70 mg and can be given twice or three times weekly. Patients treated with Oxsoralen should have a baseline eye exam, Lim recommended.

PUVA is contraindicated in patients younger than 10 years, women who are pregnant, nursing mothers and anyone with a history of melanoma, lupus erythematosus and xeroderma pigmentosum. It should also be used with caution in other patients, including those aged 10 to 18 years, and those with a history of photosensitivity, exposure to ionizing radiation, arsenic and methotrexate.

Side effects commonly noted with PUVA treatment include nausea (caused by the psoralen), phototoxicity, pruritus and nail changes. There is also some evidence that PUVA may increase the risk for basal cell carcinoma, squamous cell carcinoma and melanoma.

References

  1. Lim HW. Abstract #C016. Presented at: American Academy of Dermatology 2014 Meeting; March 21-25, 2014: Denver.

Disclosure: Lim serves as a consultant and/or investigator for several manufacturers.

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