The pharmacokinetics of methotrexate and its 7-hydroxy metabolite in patients with rheumatoid arthritis

Br J Clin Pharmacol. 1993 Apr;35(4):409-12. doi: 10.1111/j.1365-2125.1993.tb04158.x.


1. The pharmacokinetics of MTX and its 7-hydroxy metabolite (7-OHMTX) were investigated in nine patients with rheumatoid arthritis (RA). Each patient received 15 mg MTX i.v., i.m. and p.o. after an overnight fast in a randomized cross-over design. The plasma concentrations of MTX and 7-OHMTX were measured over 7 days and their urinary excretion over 24 h. 2. Plasma concentrations of MTX were described by a triexponential function after i.v. administration, a triexponential function with zero or first order absorption after oral administration, and a biexponential function with zero of first order absorption after i.m. injection. Plasma concentrations of 7-OHMTX were described by a biexponential function after all three routes of administration. The median terminal elimination half-lives of MTX and 7-OHMTX were 55 h and 116 h, respectively. The area under the plasma concentration-time curve (AUC (0,170 h)) of MTX did not differ between i.m. and oral administration indicating similar bioavailability after these routes of administration. The AUC (0,170 h) values of 7-OHMTX after i.v., oral and i.m. administration were similar. Over 80% of MTX was excreted in urine as intact drug and about 3% was excreted as 7-OHMTX during 24 h after drug administration. 3. Plasma concentrations of MTX and 7-OHMTX were measurable at the end of the dose interval in most of the patients and may help to identify non-responders or patients with increased risk of side-effects.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Aged
  • Arthritis, Rheumatoid / blood
  • Arthritis, Rheumatoid / metabolism*
  • Arthritis, Rheumatoid / urine
  • Female
  • Folic Acid Antagonists / pharmacokinetics*
  • Humans
  • Injections, Intramuscular
  • Male
  • Methotrexate / analogs & derivatives*
  • Methotrexate / blood
  • Methotrexate / pharmacokinetics*
  • Methotrexate / urine
  • Middle Aged


  • Folic Acid Antagonists
  • 7-hydroxymethotrexate
  • Methotrexate