| dc.description.abstracteng | PURPOSE Silicone oil (SO) tamponade is basically used as a mechanical tool to keep the retina reattached. It would be also effective, to use SO as a medical treatment of the underlying illness. The purpose of this study was to evaluate wheter SO can be used as a carrier for drug- delivery to guarantee a contemporary treatment of desiganted diseases. Corticosteroids are used intravitreal for numerous retinal diseases. Two efficient and intravitreal tested corticosteroids were chosen. The absolute solubility of triamcinolone (TA) and dexamethasone (DEXA) was determined in in-vitro studies and the interactions between endotamponade and TA/DEXA were monitored. METHODS A) High concentrations of TA and DEXA were mixed with SO. After 14 days at rest, the suspension was filtrated with 0.2 um filters to extract the unsolved TA and DEXA from the SO. Subsequently, deionized water was added and the release of TA and DEXA from the SO into the water has been determined at 2.5, 24, 72 and 96 hours with High-Pressure-Liquid-Chromatography (HPLC). B) Deionized water, in which moderate concentrations (1µg/ml) of TA and DEXA were solved, was overlayered with SO to determine diffusion of TA or DEXA into the SO. The concentration of TA/DEXA has been determined in the deinoized water before and after lamination with SO. C) The interactions of unsolved TA- and DEXA-crystals with SO should been evaluated. Therefore, TA or DEXA has been added to water in high concentrations to form a TA- or DEXA-WATER-SUPSENSION. Results A) DEXA was not soluble in SO. TA was soluble in very low concentrations (70ng/ml) and was release from SO into deionized water over at least 96 hours. B) No significant diffusion from TA nor DEXA into SO has been found. C) The DEXA-crystals accumulated at the bottom of the vials and showed no interaction with the SO-phase. The smaller TA-crystals accumulated in the interface between SO and water, while bigger crystals moved down to the bottom of the vials. Conclusion TA is soluble in SO at very low concentrations below therapeutic levels. TA crystals, which accumulated between the water and SO could act as a small depot and may be a reason for the fast decrease in concentration of TA injected into a SO filled eye. DEXA shows neither a solubility nor an interaction with SO.PURPOSE Silicone oil (SO) tamponade is basically used as a mechanical tool to keep the retina reattached. It would be also effective, to use SO as a medical treatment of the underlying illness. The purpose of this study was to evaluate wheter SO can be used as a carrier for drug- delivery to guarantee a contemporary treatment of desiganted diseases. Corticosteroids are used intravitreal for numerous retinal diseases. Two efficient and intravitreal tested corticosteroids were chosen. The absolute solubility of triamcinolone (TA) and dexamethasone (DEXA) was determined in in-vitro studies and the interactions between endotamponade and TA/DEXA were monitored. METHODS A) High concentrations of TA and DEXA were mixed with SO. After 14 days at rest, the suspension was filtrated with 0.2 um filters to extract the unsolved TA and DEXA from the SO. Subsequently, deionized water was added and the release of TA and DEXA from the SO into the water has been determined at 2.5, 24, 72 and 96 hours with High-Pressure-Liquid-Chromatography (HPLC). B) Deionized water, in which moderate concentrations (1µg/ml) of TA and DEXA were solved, was overlayered with SO to determine diffusion of TA or DEXA into the SO. The concentration of TA/DEXA has been determined in the deinoized water before and after lamination with SO. C) The interactions of unsolved TA- and DEXA-crystals with SO should been evaluated. Therefore, TA or DEXA has been added to water in high concentrations to form a TA- or DEXA-WATER-SUPSENSION. Results A) DEXA was not soluble in SO. TA was soluble in very low concentrations (70ng/ml) and was release from SO into deionized water over at least 96 hours. B) No significant diffusion from TA nor DEXA into SO has been found. C) The DEXA-crystals accumulated at the bottom of the vials and showed no interaction with the SO-phase. The smaller TA-crystals accumulated in the interface between SO and water, while bigger crystals moved down to the bottom of the vials. Conclusion TA is soluble in SO at very low concentrations below therapeutic levels. TA crystals, which accumulated between the water and SO could act as a small depot and may be a reason for the fast decrease in concentration of TA injected into a SO filled eye. DEXA shows neither a solubility nor an interaction with SO. | de |