In selecting volunteers for the clinical study, patients received a systemic or topical anti acne therapy 3 months before or during the study, pregnant patients, patients planning to become pregnant, lactating patients, patients with skin diseases that might interfere with the diagnosis or evaluation of their hyper pigmentation were excluded from the study. Seventy-six patients with mild to moderate acne, 8 years or older, defined as a score of 1–30 on the global acne grading system (GAGS) scale [19], who were not satisfied with their previous acne therapies participated in the double-blind clinical trial study after giving written informed consent. Permission was obtained from the Mazandaran University of Medical Sciences ethical committee before starting the study. At the first visit, a detailed questionnaire including data of demographic status, acne duration and medical history was completed for each patient. Thereafter, the patients were randomly assigned to one of the two treatment groups, namely group A (where SP-NLC gel was used) and group B (where SP-ALC gel was used). Both the physicians and patients were blinded to the type of treatment. Every morning and evening, patients washed their face with non-medicated soap, then thoroughly rinsed and dried it. Over the 8-week course, each patient applied 2 tubes (each tube contained 30 g gel with the patient instructed to apply about 1 g of the gel containing 10 mg SP for SP-NLC gel (group A) or 50 mg drug of the SP-ALC (group B) during the 8 weeks) of the formulated gel and was asked to apply about 2 cm (knuckle) of the gel each morning and evening to the area and massage it for about 2 min. They were left on individual acne lesions for 2–3 h, after which they were washed off. Non-medicated cosmetics were permitted during the study. The patients were asked about adherence to the protocol and to report any side effects. During the trial the patients were prohibited from using any drugs or other skin care treatments for acne.