ABSTRACT
Tretinoin can be used in the treatment of a variety of skin diseases, depending on its concentration. Formulations containing 0.05% tretinoin have been used in acne vulgaris. An important objective of this study was to show the fact that using hydrophilic gels [formula I] or emollient cream [formula II] as topical formulation containing 0.05% tretinoin improves clinical efficacy while potentially reducing local irritation traditionally associated with the commercially available topical tretinoin product [formula III]. The gel samples studied were formulations of 0.05% tretinoin in carbopol 940 [a synthetic polymer, formula Ia], sodium carboxymethylcellulose [a semisynthetic polymer, formula Ib], and carbogum [a natural polymer, formula Ic]. Emollient cream is a mixture of polyoxyethylene [2] stearyl ether as surfactant, cetostearyl alcohol as cosurfactant, liquid paraffin and white petrolatum as an oil phase. The aqueous phase contains preservative and 60% water. Evaluations of the suggested formulae were performed through stability studies, rheological measurements, pH determination and tretinoin assay spectrophotometrically. In-vitro permeation study was also done in hydroalcoholic solution [50:50] using Nephrophan dialysis membrane. The gel preparation with the highest diffusion rate was submitted to clinical investigation in comparison to the prepared cream as well as the commercial one. Such clinical attempt was made on 18 patients with mild to moderate acne for a period of 12 weeks regarding the clinical efficacy and the degree of reducing adverse effects. The formulations studied showed both good chemical and physical stabilities when submitted to rheological determinations, pH measurements and drug assay through out a 6-mounth period. The hydrophilic gel formulations as well as the emollient cream exhibited better release profiles if compared with the commercial cream. This fact is reflected on the clinical results as both the gel and emollient cream significantly improved therapeutic response at all evaluation time intervals together with much less erythema and burning if compared to the commercial one. But the gel form gave the most distinct results