Topical psoralen enhances UVB efficacy in psoriasis
MedWire News: Topical application of 8-methoxypsoralen (MOP) gel increases the efficacy of narrowband ultraviolet (UV)B therapy in patients with psoriasis, Turkish study findings show.
The results indicate that topical 8-MOP plus UVB leads to greater and earlier improvement compared with UVB alone and increases the chances of total clearance of psoriasis.
“This combination may be useful particularly for treatment-resistant lesions,” say Dilek Seckin (Marmara University School of Medicine, Istanbul) and colleagues.
The researchers enrolled 19 patients with plaque psoriasis. The participants received phototherapy three times a week. Two symmetrical lesions were selected as target lesions. The lesion on one side was treated with 1% 8-MOP gel 30 minutes before UVB radiation for the first 12 sessions of phototherapy, while the target lesion on the other side received no additional treatment and served as a control.
At baseline and the third, sixth, ninth, and 12th sessions, target lesions were assigned a score of 0 to 4 based on the sum of erythema, desquamation, and induration, with 0 signifying none and 4 very severe.
In all, 16 of the patients completed the study. The mean improvement on the Psoriasis Area and Severity Index (PASI) was 63%, with PASI 75 and PASI 50 responses seen in 57% and 68% of patients, respectively.
The researchers report in the journal Photodermatology, Photoimmunology & Photomedicine that, while the total score of the target lesions decreased for both lesions, the decrease was greater for the target lesion receiving 8-MOP. By the third session, the target lesion score for the lesion treated with 8-MOP was significantly lower than that for the control lesion at the sixth session.
The average percentage decrease in the target lesion score was also greater on the 8-MOP-applied lesion than the control lesion at the third, sixth, and ninth sessions of phototherapy. However, the difference was only significant at the ninth treatment session, at 58.6% versus 37.7%, respectively.
Total clearance was seen at the 8-MOP-applied lesion in four (22%) patients, whereas none of the control lesions totally cleared. By the 12th session, five 8-MOP-applied lesions had totally cleared compared with two control lesions.
Side effects were more common in 8-MOP-applied lesions than control lesions, with pigmentation the most common side effect. It was usually mild to moderate in severity and became most evident at the sixth session.
Seckin et al conclude: “Addition of a topical 8-MOP gel to ongoing phototherapy may be considered in case of an insufficient response to phototherapy.”
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By Lucy Piper