Tretinoin-loaded liposomal formulations: from lab to comparative clinical study in acne patients.

Topical tretinoin is the most commonly used retinoid for acne. However, its irritative potential on the applied area and the barrier properties of the stratum corneum limit its use. The objective of the present study was to formulate tretinoin liposomal gel to obtain a formula with lower skin irritation potential and greater clinical effect. A statistical 2(4) factorial design was adopted. Sixteen formulae prepared and were properly evaluated. A candidate formula (F13G) prepared with 0.025% tretinoin, phospholipid- cholesterol-dicetylphosphate (9:1:0.01) and incorporated in 1% carbopol gel was selected for skin irritation test. Clinical study was conducted on acne patients and compared to marketed product. All liposomes formulations were spherical in shape. The addition of cholesterol in the film hydration method significantly decreased the vesicle size, and increased the percentage of incorporation efficiency at (p < 0.05). The presence of dicetylphosphate significantly increased drug release but did not affect the percentage of incorporation efficiency and vesicle size. The results of the clinical study in acne patients revealed that F13G showed significantly higher efficacy when compared to marketed product (p < 0.05).