<p>Methotrexate has a bioavailability of 64-90%, though this decreases at oral doses above 25mg due to saturation of the carrier mediated transport of methotrexate.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Inoue K, Yuasa H: Molecular basis for pharmacokinetics and pharmacodynamics of methotrexate in rheumatoid arthritis therapy. Drug Metab Pharmacokinet. 2014;29(1):12-9. Epub 2013 Nov 26. (PubMed ID 24284432)" href="#reference-A180322">1</a></sup>. Methotrexate has a T<sub>max</sub> of 1 to 2 hours.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Inoue K, Yuasa H: Molecular basis for pharmacokinetics and pharmacodynamics of methotrexate in rheumatoid arthritis therapy. Drug Metab Pharmacokinet. 2014;29(1):12-9. Epub 2013 Nov 26. (PubMed ID 24284432)" href="#reference-A180322">1</a></sup> oral doses of 10-15µg reach serum levels of 0.01-0.1µM.<sup class="text-reference-group"><a class="reference-popover-link" data-content="Inoue K, Yuasa H: Molecular basis for pharmacokinetics and pharmacodynamics of methotrexate in rheumatoid arthritis therapy. Drug Metab Pharmacokinet. 2014;29(1):12-9. Epub 2013 Nov 26. (PubMed ID 24284432)" href="#reference-A180322">1</a></sup></p>