Abstract
Methotrexate (MTX) is the gold standard drug for the treatment of rheumatoid arthritis (RA), and it is frequently combined with leflunomide (LEF) to enhance its clinical efficacy. However, this combination can exacerbate liver toxicity, and the underlying mechanism has not yet been clarified. We investigated whether LEF affects the pharmacokinetics of MTX and its primary toxic metabolite, 7-hydroxyl methotrexate (7OH MTX), in mice. LEF significantly increased the plasma concentration (area under the plasma concentration–time curve) of MTX and 7OH MTX (2.4 and 4.5 times, respectively), decreased their bile excretion, and increased their accumulation in the liver and kidneys. When we investigated the effect of LEF on the MTX absorption, distribution, metabolism, and excretion process, we found that LEF had little effect on liver aldehyde oxidase and 7OH MTX formation. However, LEF significantly decreased the expression of the apical efflux transporter multidrug resistance–associated protein 2 (Mrp2) and increased that of the basolateral efflux transporters Mrp3/4, except there was no significant change in Mrp4 protein expression. Mrp2/3/4 alteration changed the distribution of MTX and 7OH MTX in plasma and tissues. Further studies suggested that LEF indirectly activated peroxisome proliferator–activated receptor α (PPARα), which was likely responsible for the Mrp2/3/4 alteration in the liver. The MTX plasma concentration change induced by LEF was reversed by the PPARα-specific antagonist GW6471. These results may partially explain the exacerbated liver toxicity caused by combination treatment with MTX and LEF and may raise concerns regarding the risk of potential drug-drug interactions between PPARα agonists and Mrp substrates in the clinic.
Footnotes
- Received September 11, 2017.
- Accepted March 26, 2018.
This work was supported by the “Organ Reconstruction and Manufacturing” Strategic Priority Research Program of the Chinese Academy of Sciences [Grant XDA16000000], the Independent Deployment Program of the Institute of Pharmaceutical Innovation of the Chinese Academy of Sciences [Grant CASIMM0120163012], the Hundred Talents Program of the Chinese Academy of Sciences, and the National Science Foundation of China [Grant 81573499].
↵This article has supplemental material available at molpharm.aspetjournals.org.
- Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics