Evaluation of reological behaviour and drug release from Eythromycin gel

Erythromycin acts by inhibition of protein synthesis in susceptible organisms by reversibly binding to 50S ribosomal subunits, thereby inhibiting translocation of aminoacyl transfer-RNA and inhibiting polypeptide synthesis. Erythromycin was chosen as the model drug. Erythromycin topical preparations are used for acne treatment. The aim of this work was to identify a gel with suitable rheological properties (spreadability texture and viscosity) for topical administration. First the solubility of erythromycin in different solvents was evaluated, then formulations were prepared using gelling agent (HPC), pH of the formulations was adjusted to pH 7. The stability of gels was evaluated in three different temperatures, refrigerator, room temperature and 40°C oven. The in vitro release of drug was assessed using static diffusion cell with dialysis membrane. The concentration of drug was analyzed by means of UV spectrophotometer at 208.6 nm. Our findings showed that increasing the amount of gelling agent, induced decreasing the drug release mean while decreasing the amount of ethanol and increasing the amount of glycerin increased the release of drug. The results showed that release of drug follows first order release mechanism. These findings show that suitable spreadability and viscosity, that permitted the most rapid release of the active principle (and hence the shortest delay in transdermal absorption).