title: Methotrexate pharmacokinetics and effects in women receiving methotrexate 50 mg and 60 mg per square meter for early abortion.
abstract: OBJECTIVE
  Our goal was to evaluate the pharmacokinetics and safety of methotrexate in doses of 50 mg/m2 and 60 mg/m2 in regimens for early abortion.
  
  
  METHODS
  A randomized controlled trial was performed in women requesting an abortion at < or = 49 days' gestation. Twenty women were treated with intramuscular methotrexate 50 mg/m2 (group 1) or 60 mg/m2 (group 2). Methotrexate levels were determined serially for the first 24 hours, then every 24 hours for 7 days. On the seventh day misoprostol 800 microg was administered vaginally. The misoprostol dose was repeated 24 hours later if abortion did not occur.
  
  
  RESULTS
  Complete abortion occurred in 9 of 10 (90%, 95% confidence interval 56% to 100%) patients in group 1 and all 10 (100%, 95% confidence interval 69% to 100%; p = 0.99) in group 2. Methotrexate levels peaked within 1 to 2 hours and were nondetectable within 48 hours in all patients in group 1 and 72 hours in group 2. Both the maximum concentration of methotrexate and the area under the curve were significantly greater for group 2. Methotrexate clearance rates were 7.89 +/- 1.98 L/hr and 5.55 +/- 0.83 L/hr (p = 0.003), respectively.
  
  
  CONCLUSIONS
  The serum levels of intramuscular methotrexate with 50 mg/m2 and 60 mg/m2 regimens indicate that these are safe treatment doses. Methotrexate 50 mg/m2 intramuscularly has the same clearance rates when administered during pregnancy as in a nonpregnant state, and maximum concentrations do not reach sustained toxic levels.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pennsylvania, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Creinin
authors.forename: M A
authors.initials: MA
authors.lastname: Krohn
mesh_terms: D000020:Abortifacient Agents, Nonsteroidal / Q000627:therapeutic use; D000028:Abortion, Induced; D000328:Adult; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008727:Methotrexate / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D016595:Misoprostol / Q000627:therapeutic use; D011247:Pregnancy
chemical_list: D000020:Abortifacient Agents, Nonsteroidal; D016595:Misoprostol; D008727:Methotrexate