Methotrexate can be administered orally, intramuscularly, intravenously, or intrathecally. The route of administration depends on the condition being treated. For instance, low-dose oral methotrexate is common in rheumatoid arthritis, while higher doses might be used in chemotherapy regimens. The pharmacokinetics of methotrexate varies, with oral bioavailability ranging from 70% at lower doses to 20% at higher doses due to saturation of absorption mechanisms.
