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Updated: Jul 14, 2026

Comprehensive Evaluation of the Effectiveness and Safety of Placenta-Targeted Drug Delivery Using Three Complementary Methods
Published on: September 10, 2018
7-Hydroxymethotrexate as a urinary metabolite in human subjects and rhesus monkeys receiving high dose methotrexate
Abstract:
Human subjects and rhesus monkeys receiving the antitumor agent methotrexate at the high dose levels recently introduced into clinical use (greater than 50 mg/kg) excrete significant amounts of the metabolite 7-hydroxymethotrexate. The metabolite is not detected in these species after methotrexate therapy at conventional dose levels. The evidence indicates that in primates, the in vivo conversion of methotrexate to 7-hydroxymethotrexate is a dose-dependent phenomenon, with the enzyme system(s) catalyzing the reaction having a low affinity for the drug.
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