Abstract
We recently cloned and characterized the rat kidney-specific organic anion transporter, OAT-K1, which was suggested to mediate renal tubular transport of methotrexate. In this study, we investigated the interactions of nonsteroidal anti-inflammatory drugs (NSAIDs) with OAT-K1 by evaluating the effects of these drugs on renal distribution of methotrexate in vivo, and on methotrexate accumulation in the stably transfected LLC-PK1 cells expressing OAT-K1 (LLC-OAT-K1). NSAIDs such as indomethacin and ketoprofen had significant inhibitory effects on renal accumulation of methotrexate in rats after coadministration. Indomethacin and ketoprofen inhibited methotrexate accumulation by LLC-OAT-K1 cells in a competitive manner with the apparent inhibition constant values of 1.0 mM and 1.9 mM, respectively. Other NSAIDs including ibuprofen, flufenamate and phenylbutazone also showed potent inhibitory effects on methotrexate accumulation. However, indomethacin was not transportedvia OAT-K1. These results indicate that NSAIDs have potent inhibitory effects against the OAT-K1-mediated methotrexate transport, which suggests that the OAT-K1 may be one of interaction sites for methotrexate and NSAIDs in the kidney.
Footnotes
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Send reprint requests to: Professor Ken-ichi Inui, Ph.D., Department of Pharmacy, Kyoto University Hospital, Sakyo-ku, Kyoto 606–01, Japan.
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↵1 This work was supported by a Grant-in-Aid for Scientific Research (B) and a Grant-in Aid for Scientific Research on Priority Areas of “Channel-Transporter Correlation” from the Ministry of Education, Science, and Culture of Japan, and by the Japan Research Foundation for Clinical Pharmacology.
- Abbreviations:
- NSAID
- nonsteroidal anti-inflammatory drug
- oatp
- organic anion-transporting polypeptide
- Received March 11, 1997.
- Accepted August 6, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
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