title: A bioreversible prodrug approach designed to shift mechanism of brain uptake for amino-acid-containing anticancer agents.
abstract: By derivatization at the N-terminus of amino acid-based anticancer agents (e.g. melphalan and acivicin) to form a drug delivery system (TDDS), we demonstrate a change in the mechanism of brain uptake from the large neutral amino acid transporter (LAT) pathway to passive. An in situ rat brain perfusion technique was used to determine the brain capillary permeability-surface area (PA) product for [(14)C]L-Leu as control (5.18 +/- 0.32 x 10(-2) mL/s/g), which was inhibited competitively (to 7-18% of control) by an excess concentration of the amino-acid-containing anticancer agents, acivicin and melphalan. However, TDDS did not compete for LAT-mediated brain uptake of the radiotracer [(14)C]L-Leu. Brain uptake of TDDS was determined after in situ brain perfusion followed by RP-HPLC along with LC-MS/MS detection of the analytes in brain samples. The PA product for CH(3)-TDDS containing melphalan (5.09 +/- 2.0 x 10(-2) mL/s/g) shows that these agents rapidly cross the blood-brain barrier. Furthermore, competition studies of CH(3)-TDDS with [(3)H]verapamil suggest that the TDDS interacts significantly with the multidrug resistant efflux system (P-glycoprotein) at the blood-brain barrier. Therefore, TDDS were shown to lack LAT-mediated brain uptake. The drug delivery systems, however, showed uptake predominantly via the passive route along with recognition by the multidrug resistant efflux protein at the cerebrovasculature.
authors.affiliation: Department of Pharmaceutical Sciences, University of Maryland, Baltimore, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Killian
authors.forename: P J
authors.initials: PJ
authors.lastname: Chikhale
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D026905:Amino Acid Transport Systems; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics; D001667:Binding, Competitive / Q000187:drug effects; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004337:Drug Carriers / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics; D066298:In Vitro Techniques; D007555:Isoxazoles / Q000378:metabolism / Q000493:pharmacokinetics; D008297:Male; D008558:Melphalan / Q000378:metabolism / Q000493:pharmacokinetics; D010477:Perfusion; D011355:Prodrugs / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics; D011849:Radioactive Tracers; D051381:Rats; D017207:Rats, Sprague-Dawley; D014700:Verapamil / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D026905:Amino Acid Transport Systems; D000596:Amino Acids; D000970:Antineoplastic Agents; D002352:Carrier Proteins; D004337:Drug Carriers; D007555:Isoxazoles; D011355:Prodrugs; D011849:Radioactive Tracers; D014700:Verapamil; C006303:acivicin; D008558:Melphalan