Preparation Of Benzoyl Peroxide Gel

Benzoyl peroxide(BPO)is a kind of strong oxidant,which is used for acne caused by propionibacterium acnes(PANCNE).BPO product formulated as gel was first approved in Canada and then launched in other countries in succession.In China,BPO gel was first approved to be imported in year 2002.BPO is metabolized into benzoic acid in skin and release free oxygen which can kill PANCAE and also cause skin drying and desquamating.In this study,we chose Benzihex? AC Gel produced by Galderma(Paris,France)as reference preparation,and developed self-made BPO gel by prescription and preparation screening and optimization,which in qualities was consistent with the reference preparation.First we established and validated determination methods of BPO assay,impurities,dissolution in vitro,transcutaneous permeation in vitro and skin retention,as well as determination methods of benzoic acid transcutaneous permeation in vitro and skin retention.BPO gel was prepared and compared in-vitro equivalence with reference preparation.Agar gel diffusion method was used to determine diffusion coefficient(K)of BPO,which served as an index of single-factor experiment for composition screening.The diameter(d0.9)of API particles was determined as 5.86?m and the percentage of Poloxamer 407 and Carbomer 980 respectively 0.3% and 1.5% in optimized prescription.Receiving medium was chosen with reference to the data of saturated solubility in different mediums.The comparability of release curves between self-made gel and reference gel was determined by similarity factor(f2),and the result revealed that the similarity of the two was high(f2=72).The transcutaneous permeation test was carried out using pig skin.The concentrations of BPO in receiving medium,on surface and inside the skin as well as benzoic acid inside skin were determined by HPLC.The results showed that most BPO in either self-made gel or reference gel were retained on the surface of skin,a small amount of BPO and benzoic acid were detected inside skin.The anti-bacteria test in vitro showed that the diameter of inhibition zones of self-made gel and reference gel were similar.Rabbit ear acne model was established and preliminary pharmacodynamics was then studied,which found that self-made gel had the same therapeutic effect as reference gel.In conclusion,through prescription and preparation optimizing self-made gel is consistent with the commercial reference gel.