title: Dextran-methylprednisolone succinate as a prodrug of methylprednisolone: local immunosuppressive effects in liver after systemic administration to rats.
abstract: OBJECTIVE
  The purpose of this work was to study the local immunosuppressive effects of systemically administered methylprednisolone (MP) and its prodrug, dextran-methylprednisolone (DMP), in rat livers.
  
  
  METHODS
  Single 5 mg/kg (MP equivalent) doses of MP or DMP were injected intravenously to rats, and livers were isolated at different time points (0-72 h; n = 4/time point). Isolated livers were stimulated ex vivo with bacterial lipopolysaccharide, and outlet perfusate and bile samples were analyzed for their concentrations of tumor necrosis factor (TNF)-alpha by enzyme-linked immunosorbent assay. The area under the perfusate TNF-alpha concentration-time curve (AUC) was used as a measure of immune response. Hepatic concentrations of MP and DMP were also measured by high-performance liquid chromatography.
  
  
  RESULTS
  Both MP and DMP resulted in a decrease in lipopolysaccharide-induced increase in TNF-alpha AUC. MP injection 8 h before liver isolation resulted in a maximum of 50% decrease in TNF-alpha AUC. Compared with MP, the maximum effect of the prodrug (DMP) was both more intense (approximately 80% reduction in TNF-alpha AUC) and delayed (maximum inhibition at 24 h). Overall, the area under the effect (% inhibition of TNF-alpha)-time (%inhibition-h) for DMP (3,680 +/- 406) was approximately four times more than that for the parent drug (846 +/- 114). Whereas the MP concentrations in the liver were not quantifiable after the injection of the parent drug, relatively large concentrations of DMP and regenerated MP were found in the liver of DMP-injected rats.
  
  
  CONCLUSIONS
  After systemic administration to rats, both MP and DMP exhibit local immunosuppressive effects in the liver. The local effects of the prodrug (DMP), however, appear to be more intense and sustained than those of the parent drug (MP).
authors.affiliation: School of Pharmacy, Texas Tech University Health Sciences Center, 1300 Coulter, Amarillo, Texas 79106, USA.
authors.forename: Anjaneya P
authors.initials: AP
authors.lastname: Chimalakonda
authors.forename: Reza
authors.initials: R
authors.lastname: Mehvar
mesh_terms: D000818:Animals; D003911:Dextrans / Q000008:administration & dosage*; D004338:Drug Combinations; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008776:Methylprednisolone Hemisuccinate / Q000008:administration & dosage*; D011355:Prodrugs / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D003911:Dextrans; D004338:Drug Combinations; D007166:Immunosuppressive Agents; D011355:Prodrugs; D014409:Tumor Necrosis Factor-alpha; D008776:Methylprednisolone Hemisuccinate