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

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.