PERMEATION AND CONCENTRATION OF ERYTHROMYCIN BY SUPPORTED AND EMULSION LIQUID MEMBRANES

Erythromycin, a macrolide antibiotic, permeates through liquid membran es without a carrier. The contribution of local resistances to the ove rall permeation resistance is conceived from the permeation mechanism. According to measured distribution equilibria of erythromycin between aqueous and oil phases and previously reported dissociation equilibri um of erythromycin in the aqueous phase, the distribution coefficient of free erythromycin is constant for each oil phase and independent of proton concentration. In a supported liquid membrane, a high degree o f concentration is attained in the case of a 1-decanol membrane. Not o nly the membrane phase but also the two aqueous phases contribute to o verall resistance. For the heptane membrane, the controlling step is p redicted to be in the membrane phase. An emulsion liquid membrane also concentrates erythromycin in the stripping phase, however, it gives a low degree of concentration which is ascribed to undesirable reductio n of the overall permeation coefficient. For a m-xylene membrane, the controlling resistance is in the membrane and stripping phases, and fo r the heptane membrane, it is in the membrane phase.