Liposomal Methylene Blue Hydrogel for Selective Photodynamic Therapy of Acne Vulgaris

Background: Photodynamic therapy (PDT) has been proposed as a treatment option for acne vulgaris. The authors have proposed in this work a liposomal delivery for methylene blue (MB) for selective acne treatment.

Objectives: To evaluate the efficacy and tolerability of liposomes loaded methylene blue (LMB) based photodynamic therapy in patients with mild-to-moderate acne vulgaris in a randomized, controlled and investigator blinded study.

Materials and methods: Liposomes loaded methylene blue (LMB) was prepared and studied for different pharmaceutical properties and formulated in hydrogel (MB 0.1%). Permeability and selective sebaceous gland targeting in mice skin was studied. Gel containing LMB was used for treating 13 patients complaining of mild-moderate acne vulgaris once a week for two weeks. Efficacy evaluation included changes in lesions counts, clinical assessments of clinical improvement by patients and evaluating dermatologists. Pain and local adverse effects were also evaluated.

Results: The mechanism of the drug released from liposomes (both in pH=5.5 and in pH=7.2) was following zero order kinetics with significant increase in the drug released in pH=5.5. Drug released from free methylene blue (FMB) gel was significantly higher (P≤0.05) with Higuichi’s diffusion model than LMB gel, which followed zero order kinetics. Free MB gel showed superficial destruction in the mice hair shaft while LMB showed complete destruction of pilosebaceous unit. After only two sessions, there was a 83.3% reduction in the number of inflammatory acne lesions and a 63.6% reduction in the number of non-inflammatory acne lesions. At 12 weeks, 90% of patients had a moderate-to-marked improvement of their acne in the treated areas. Most patients had no pain; also no serious adverse side effects were recorded. All the patients had no edema. Slight transient hyperpigmentation was seen only in three patients.

Conclusion: Liposomal MB hydrogel selectively delivered MB to sebaceous gland and was effective in photodynamic treatment of mild-to-moderate acne vulgaris.