Bernd U Riebesehl

Learn More
Root cultures of Senecio vulgaris, S. vernalis, S. erucifolius and S. squalidus were established. The patterns of pyrrolizidine alkaloids found in these root cultures were analyzed by high-resolution GC and GC-MS and compared with the alkaloids present in the respective plants. In vitro cultured roots produce alkaloid patterns and accumulate quantities(More)
Purpose. Appropriate physicochemical parameters are desired for the prediction of passive intestinal drug absorption during lead compound selection and drug development. Methods. Liposome distribution coefficients measured titrimetrically and solubility data at pH 6.8 were used to characterize 21 structurally diverse ionizable drugs covering a range from(More)
Drug partitioning to liposomes has been suggested as a model for partitioning to biomembranes but has been lacking a rapid analytical assay useful for drug screening. A fast pH-metric titration method for the determination of liposome partitioning of ionizable drugs using small unilamellar phosphatidylcholine vesicles prepared by sonic homogenization has(More)
Cholesterol esterase (CE) induced surface erosion of poly(ethylene carbonate) (PEC) and drug release from PEC under mild physiological environment was investigated. The degradation process was monitored by changes of mass and molecular weight (MW) and surface morphology of polymer films. During the whole period of degradation, MW of PEC was unchanged. Water(More)
The objective of this study was to investigate the effect of molecular weight (MW) on the drug release from poly(ethylene carbonate) (PEC) based surface-eroding in situ forming depots (ISFD). In phosphate buffered saline (PBS) pH 7.4, 63.7% of bovine serum albumin BSA was released from high MW PEC of 200 kDa (PEC200) in DMSO (15%, w/w) in 2 days, while(More)
We present an in situ hydrophobic salt forming technique for the encapsulation of weakly hydrophobic, ionizable active pharmaceutical ingredients (API) into stable nanocarriers (NCs) formed via a rapid precipitation process. Traditionally, NC formation via rapid precipitation has been difficult with APIs in this class because their intermediate solubility(More)
Macrophage induced surface degradation of poly(ethylene carbonate) (PEC) was investigated under in vitro conditions. Degradation of PEC with the MW of 41 kDa (PEC41) was slower than that of PEC with the MW of 200 kDa (PEC200). In terms of macrophage mediated drug release from PEC matrix, in cell-free medium, less than 1% of levofloxacin was released from(More)
  • 1