title: Prodrug approach for alphaIIbbeta3-peptidomimetic antagonists to enhance their transport in monolayers of a human intestinal cell line (Caco-2): comparison of in vitro and in vivo data.
abstract: OBJECTIVE
  Different lipophilic derivatives of a potent alphaIIbbeta3-antagonist with benzamidino-oxazolidinone structure were investigated with respect to transport and metabolism properties to evaluate their potential as prodrugs with improved absorption behavior.
  
  
  METHODS
  Intestinal transport and metabolism of the compounds were studied in Caco-2 monolayers under in vitro conditions and quantitated by a reversed-phase HPLC- method. Peroral bioavailability in cynomolgus monkeys and inhibition of platelet aggregation (guinea pig) were compared to in vitro permeability coefficients.
  
  
  RESULTS
  N-alkoxycarbonyl- and N-benzoyl-derivatization of the benzamidine-parent drug increased the apparent permeabilities across Caco-2 monolayers by a factor of 25-100 fold. Most prodrugs were transported mainly by passive diffusion, whereas the methoxycarbonyl-derivative EMD 122347 displayed directional transport from basolateral (BL) to apical (AP). This polarized efflux was concentration dependent (saturable kinetics with Km = 207 microM, Vmax = 0.275 nmol cm(-2) min(-1)) and could be reduced in the presence of verapamil (300 microM), an inhibitor of p-glycoprotein. Cell mediated cleavage of the prodrugs was low and showed only slight differences to hydrolysis in buffer solution, indicating a predominantly non enzymatic cleavage. Both peroral bioavailability (monkey) and the inhibition of ex-vivo platelet aggregation (guinea pig) gave the same rank order as the permeability coefficients obtained in Caco-2 monolayers.
  
  
  CONCLUSIONS
  Alkoxycarbonylamidine- and benzoylamidine promoieties of a RGD mimetic alphaIIbbeta3-antagonist considerably increased both effect bioavailabilities in animal experiments as well as in-vitro permeability in cell monolayers, demonstrating the potential of this approach to enhance transport of peptidomimetic drugs.
authors.affiliation: Department of Pharmaceutics and Biopharmacy, University of Marburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Kamm
authors.forename: P
authors.initials: P
authors.lastname: Raddatz
authors.forename: J
authors.initials: J
authors.lastname: Gante
authors.forename: T
authors.initials: T
authors.lastname: Kissel
mesh_terms: D000818:Animals; D001692:Biological Transport; D001711:Biotransformation; D002021:Buffers; D018938:Caco-2 Cells; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D004594:Electrophysiology; D006168:Guinea Pigs; D006801:Humans; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects*; D008252:Macaca fascicularis; D000442:Octanols / Q000737:chemistry; D010974:Platelet Aggregation / Q000187:drug effects; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors*; D011355:Prodrugs / Q000737:chemistry* / Q000493:pharmacokinetics*; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002021:Buffers; D000442:Octanols; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D011355:Prodrugs