ADHESIVE AND SPREADING PROPERTIES OF PHARMACEUTICAL GEL COMPOSED OF CELLULOSE POLYMER

Salicylic acid (SA) is an ideal exfoliant for use on acne and acne-prone skin. It was chosen as the model drug. Samples were prepared by simple dispersing different hydroxypropyl cellulose (HPC) amounts (0.5-2%) in isopropyl alcohol solution and keeping in 4, 25 and 40°C. In all these systems viscosity, spreading, adhesive properties and drug release were characterized. The silastic membrane was employed as a barrier in Franz diffusion cell to study in vitro drug release. The concentration of drug was analyzed by means of UV spectrophotometer at the maximum wave length of 302 nm. The increasing in HPC concentration caused increased viscosity. A relationship between the viscosity and bioadhesive strength was shown by HPC gels. The results demonstrated that the flux of SA decreased with increase in pH and SA permeation conformed to the pH partition hypothesis. The results showed that increasing of the HPC concentration caused in a reduction of SA release rate SA from gels and increasing of HPC was related to an increased viscosity of formulation. Also an increase in the ratio of collodion: drug (2:1) and a decrease in the ratio of isopropyl alcohol: drug (less than 3:1) caused the decrease of transparency of gel and the release rate. The results showed that diffusion of SA gel followed peppas model.