New topical photodynamic therapy for treatment of hidradenitis suppurativa using methylene blue niosomal gel: a single‐blind, randomized, comparative study

Summary Background Hidradenitis suppurativa ( HS ), is a chronic, recurrent dermatosis affecting skin that contains apocrine glands. Photodynamic therapy using aminolaevulinic acid ( ALA ) activated by intense pulsed light ( IPL ) have shown variable success rates, with some adverse effects. Aims To evaluate the efficacy and safety of methylene blue ( MB ) as a photosensitizer delivered as a niosomal gel for the treatment of HS using IPL . Methods We enrolled 11 patients with HS in the study, which was a randomized split‐body study. One side of each patient's body was treated with niosomal MB ( NMB ) gel and the other side was treated with unloaded (free) MB ( FMB ) gel. The affected sites were irradiated using IPL with a 630 nm filter. Patients were followed up at 1, 3 and 6 months after treatment. Results Drug release from the FMB gel was significantly higher ( P  > 0.05) than from the NMB gel. Lesions showed 77.3% and 44.1% reduction on the NMB and FMB sides, respectively. A significant reduction in the Hidradenitis Suppurativa Lesion, Area and Severity Index ( HS ‐ LASI ) after treatment was elicited in both groups, with no pain, erythema or hyperpigmentation. Conclusion The combination of MB as a photosensitizer activated with 630 nm IPL as a light source is a successful PDT for HS . Delivery of MB in niosomes was more effective for drug penetration to the dermis compared with delivery by FMB gel. The 630 nm filter was not only a source of activation of MB but also a means of hair‐follicle destruction.