Characterization of methotrexate transport and its drug interactions with human organic anion transporters.
Life-threatening drug interactions are known to occur between methotrexate and nonsteroidal anti-inflammatory drugs (NSAIDs), probenecid, and penicillin G. The purpose of this study was to characterize methotrexate transport, as well as to determine the site and the mechanism of drug interactions in the proximal tubule. Mouse proximal tubule cells stably expressing basolateral human organic anion transporters (hOAT1 and hOAT3) and apical hOAT (hOAT4) were established. The K(m) values for hOAT1-, hOAT3-, and hOAT4-mediated methotrexate uptake were 553.8 microM, 21.1 microM, and 17.8 microM, respectively. NSAIDs (salicylate, ibuprofen, ketoprofen, phenylbutazone, piroxicam, and indomethacin), probenecid, and penicillin G dose dependently inhibited methotrexate uptake mediated by hOAT1, hOAT3, and hOAT4. Kinetic analysis of inhibitory effects of these drugs on hOAT3-mediated methotrexate uptake revealed that these inhibitions were competitive. The K(i) values for the effects of salicylate, phenylbutazone, indomethacin, and probenecid on hOAT3-mediated methotrexate uptake were comparable with therapeutically relevant plasma concentrations of unbound drugs. In addition, in the presence of human serum albumin, the K(i) values were comparable with therapeutically relevant total plasma concentrations of drugs. In conclusion, these results suggest that methotrexate is taken up via hOAT3 and hOAT1 at the basolateral side of the proximal tubule and effluxed or taken up at the apical side via hOAT4. In addition, hOAT1, hOAT3, and hOAT4 are the sites of drug interactions between methotrexate and NSAIDs, probenecid, and penicillin G. Furthermore, it was predicted that hOAT3 is the site of drug interactions between methotrexate and salicylate, phenylbutazone, indomethacin, and probenecid in vivo.
Department of Pharmacology and Toxicology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka-shi, Tokyo 181-8611, Japan.
Michio
M
Takeda
Suparat
S
Khamdang
Shinichi
S
Narikawa
Hiroaki
H
Kimura
Makoto
M
Hosoyamada
Seok Ho
SH
Cha
Takashi
T
Sekine
Hitoshi
H
Endou
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D007700:Kinetics; D027381:Liver-Specific Organic Anion Transporter 1; D008727:Methotrexate / Q000493:pharmacokinetics*; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins; D029362:Organic Anion Transporters, Sodium-Independent / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010653:Phenylbutazone / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024683:Potassium Channels, Tandem Pore Domain; D011339:Probenecid / Q000494:pharmacology
D000894:Anti-Inflammatory Agents, Non-Steroidal; D027381:Liver-Specific Organic Anion Transporter 1; D009419:Nerve Tissue Proteins; D029362:Organic Anion Transporters, Sodium-Independent; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; C490280:SLC22A7 protein, human; C498886:SLC22A9 protein, human; C490281:Slc22a7 protein, mouse; C498887:Slco1b2 protein, mouse; C114338:organic anion transport protein 3; C420132:potassium channel subfamily K member 3; D010653:Phenylbutazone; D011339:Probenecid; D007213:Indomethacin; D008727:Methotrexate