Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
MEXATE vs CLADRIBINE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
MEXATE is an antimetabolite that inhibits dihydrofolate reductase (DHFR), reducing tetrahydrofolate synthesis and interfering with DNA, RNA, and protein synthesis. It also inhibits thymidylate synthetase and has immunomodulatory and anti-inflammatory effects.
Cladribine is a purine nucleoside analog that is phosphorylated intracellularly to its active triphosphate form, which inhibits DNA synthesis and repair, leading to cell death, particularly in lymphocytes. It also depletes adenosine deaminase (ADA) and accumulates in cells with high deoxycytidine kinase activity.
Rheumatoid arthritis (moderate to severe active disease in adults),Polyarticular juvenile idiopathic arthritis,Psoriasis (severe, recalcitrant, disabling),Neoplastic diseases: gestational choriocarcinoma, chorioadenoma destruens, hydatidiform mole; acute lymphocytic leukemia (ALL); meningeal leukemia; Burkitt lymphoma; advanced non-Hodgkin lymphomas; mycosis fungoides; advanced head and neck cancer; osteosarcoma (adjunctive treatment),Off-label: ectopic pregnancy, inflammatory bowel disease, graft-versus-host disease, sarcoidosis, systemic lupus erythematosus, vasculitis
FDA-approved: Treatment of hairy cell leukemia.,Off-label: Chronic lymphocytic leukemia (CLL), multiple sclerosis (relapsing forms), Waldenström macroglobulinemia, cutaneous T-cell lymphoma, and as part of conditioning regimens for hematopoietic stem cell transplantation.
10-25 mg/m2 orally or intramuscularly once weekly for rheumatoid arthritis; 50 mg/m2 intravenously once weekly for psoriasis; 30-40 mg/m2 intravenously weekly for certain cancers (dose varies by protocol).
0.09 mg/kg/day IV over 2 hours for 7 consecutive days; or 0.14 mg/kg/day IV over 2 hours for 5 consecutive days (total dose 0.7 mg/kg per course).
Terminal elimination half-life is 3-10 hours for low-dose therapy (≤30 mg/m²). For high-dose therapy (>100 mg/m²), terminal half-life extends to 8-15 hours due to saturable elimination. A third, prolonged terminal phase (8-72 hours) is observed in some patients due to enterohepatic recirculation.
Terminal elimination half-life is approximately 5.4 hours (range 4.6–6.7 hours) after intravenous administration; prolonged in renal impairment.
Methotrexate is primarily metabolized by hepatic aldehyde oxidase to 7-hydroxymethotrexate. It undergoes polyglutamation intracellularly. Less than 10% is metabolized by cytochrome P450 enzymes. Excretion is primarily renal via glomerular filtration and active tubular secretion.
Cladribine is primarily metabolized intracellularly by deoxycytidine kinase to its active triphosphate. It is also phosphorylated by deoxyguanosine kinase in mitochondria. Catabolism involves deamination by adenosine deaminase (ADA) to 2-chloroadenine, which is further metabolized.
Renal excretion of unchanged drug is the primary route of elimination, accounting for 80-90% of the dose. Biliary/fecal excretion is minor (<10%).
Renal (approximately 50% as unchanged drug); fecal elimination is minimal (<5%).
50-60% bound, primarily to albumin.
Approximately 20–30% bound to plasma proteins.
0.4-0.8 L/kg (total body water). Vd increases with dose, indicating tissue distribution.
Approximately 4.5 L/kg (range 2.3–9.6 L/kg), indicating extensive tissue distribution.
Oral: 30-70% (dose-dependent, saturable absorption). Intramuscular: 80-100%. Subcutaneous: approximately 100%.
Oral: approximately 37–55% (first-pass metabolism); subcutaneous: approximately 100%.
GFR >50 m L/min: no adjustment; GFR 10-50 m L/min: reduce dose by 50%; GFR <10 m L/min: avoid use.
GFR <50 m L/min: reduce dose by 50%; GFR <10 m L/min: avoid use.
Child-Pugh A: 75% of normal dose; Child-Pugh B: 50% of normal dose; Child-Pugh C: contraindicated.
Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: contraindicated.
For leukemia: 20-40 mg/m2 orally or intravenously once weekly; for juvenile idiopathic arthritis: 10-15 mg/m2 orally once weekly (max 25 mg/week).
0.09 mg/kg/day IV over 2 hours for 7 consecutive days; or 0.14 mg/kg/day IV over 2 hours for 5 consecutive days (total dose 0.7 mg/kg per course). No specific pediatric dose adjustments beyond weight-based dosing.
Start at lowest effective dose (e.g., 5-7.5 mg/week) with close monitoring of renal function, hepatic function, and hematologic parameters due to increased toxicity risk.
No specific dose adjustment recommended; monitor renal function and adjust accordingly.
Boxed Warning: Methotrexate (MEXATE) can cause severe or fatal toxicities including bone marrow suppression, hepatic fibrosis/cirrhosis, pulmonary fibrosis, renal failure, and ulcerative stomatitis. Fatalities have been reported with inadvertent daily dosing instead of weekly. For rheumatoid arthritis and psoriasis, use only in patients with severe disease. Monitor for toxicity closely. Advise patients about risks of fatal toxicity.
WARNING: Neurotoxicity and Hematologic Toxicity. Cladribine can cause severe bone marrow suppression (neutropenia, anemia, thrombocytopenia) and neurotoxicity (including paralysis, coma, and death). Dose-dependent and more frequent in high doses.
Severe hematologic toxicity (bone marrow suppression, pancytopenia), hepatotoxicity (fibrosis, cirrhosis, acute hepatitis), pulmonary toxicity (pneumonitis, fibrosis), renal toxicity, gastrointestinal toxicity (stomatitis, ulceration), neurotoxicity (leukoencephalopathy), opportunistic infections, tumor lysis syndrome, photosensitivity, and dermatologic reactions. Avoid concomitant NSAIDs, salicylates, and nephrotoxic drugs. Monitor CBC, LFTs, creatinine, and chest imaging. Use caution in elderly, debilitated, or patients with renal impairment, ascites, or pleural effusions.
Myelosuppression: Monitor blood counts regularly; dose adjustment or discontinuation may be needed.,Neurotoxicity: Risk increased with high doses and in patients with renal impairment.,Nephrotoxicity: Use with caution in renal impairment; reduce dose if Cr Cl < 60 m L/min.,Hepatotoxicity: Monitor liver function tests.,Secondary malignancies: Increased risk of myelodysplasia and acute myeloid leukemia.,Infections: Increased susceptibility due to lymphopenia; consider prophylaxis.
Hypersensitivity to methotrexate, alcohol abuse, pre-existing liver disease (including hepatitis), renal impairment (creatinine clearance < 60 m L/min), pre-existing bone marrow suppression, immunodeficiency, active infections (e.g., tuberculosis), pregnancy, breastfeeding, lactation.
Hypersensitivity to cladribine or any component of the formulation.,Pre-existing severe bone marrow suppression (e.g., neutropenia, thrombocytopenia) unless due to underlying disease.,Pregnancy: Can cause fetal harm.,Lactation: Discontinue nursing or drug.
Avoid alcohol due to increased hepatotoxicity risk. No specific food restrictions; however, maintain adequate hydration. Folate-rich foods do not interfere but supplemental folic acid may be prescribed to reduce side effects.
No significant food interactions. Avoid grapefruit juice due to potential CYP3A4 interaction (though minimal). Maintain adequate hydration to prevent tumor lysis syndrome in hematologic malignancies.
Category X. 1st trimester: High risk of CNS, craniofacial, and skeletal malformations. 2nd and 3rd trimesters: Fetal growth restriction, oligohydramnios, and neonatal pancytopenia.
FDA Pregnancy Category D. First trimester: Avoid due to known teratogenicity in animal studies (skeletal and visceral malformations) and potential for MDS and AML. Second and third trimesters: Risk of fetal myelosuppression, intrauterine growth restriction, and preterm labor. Cladribine crosses the placenta and may cause fetal hematopoietic suppression.
Contraindicated. Methotrexate is excreted in human milk; M/P ratio approximately 0.08. Potential for severe neonatal toxicity.
Contraindicated during breastfeeding. Cladribine is excreted into human milk; M/P ratio not determined. Potential for severe adverse effects in nursing infants, including myelosuppression and immunosuppression. Discontinue breastfeeding during therapy and for at least 7 days after last dose.
Not applicable; contraindicated in pregnancy. If inadvertent exposure, discontinue and refer for fetal assessment.
No established dose adjustments in pregnancy. Use is contraindicated. If unavoidable, lowest effective dose and close monitoring for maternal and fetal toxicity. Pharmacokinetic changes in pregnancy (increased volume of distribution, renal clearance) may reduce exposure; however, risks outweigh benefits.
Mexate (methotrexate) is a folate analog antimetabolite used in high doses for malignancy and low doses for autoimmune diseases. Reserve leucovorin rescue for high-dose protocols to prevent severe myelosuppression. Monitor renal function and methotrexate levels; adjust hydration and alkalinization to prevent precipitation in renal tubules. Avoid concurrent NSAIDs and proton pump inhibitors which reduce methotrexate clearance. Screen for pregnancy before initiation. Administer weekly in low-dose regimens for rheumatoid arthritis to avoid acute toxicity.
Cladribine is a purine nucleoside analog that causes lymphocyte depletion, effective in hairy cell leukemia and multiple sclerosis. Monitor for severe lymphopenia, opportunistic infections (e.g., herpes zoster, tuberculosis), and delayed myelosuppression. Do not administer live vaccines during or after treatment. Due to high bioavailability after subcutaneous administration, adjust dose for renal impairment. Hypersensitivity reactions may occur; premedicate with antihistamines if needed.
Take exactly as prescribed—do not increase dose or frequency. Overdose can be fatal.,Avoid alcohol completely while on this medication.,Report any signs of infection, unusual bleeding, bruising, or mouth sores immediately.,Use effective contraception during treatment and for at least 3 months after stopping.,Do not take NSAIDs or aspirin without consulting your doctor.,Stay well hydrated; drink plenty of fluids unless otherwise instructed.,Avoid live vaccines during treatment.,Keep all follow-up appointments for blood tests and monitoring.
Cladribine can significantly lower your white blood cell count, increasing infection risk. Report fever, chills, or sore throat immediately.,Avoid live vaccines (e.g., MMR, shingles) during and for at least 6 months after treatment.,You may experience fatigue, nausea, headache, or skin reactions at injection site. These are common but report severe symptoms.,Use effective contraception during treatment and for at least 6 months after the last dose. Cladribine may harm a fetus.,You will need regular blood tests to monitor your blood cell counts, liver, and kidney function.
No interactions on record
"The combination of cabazitaxel and cladribine may potentiate myelosuppression due to overlapping bone marrow toxicity profiles. Cabazitaxel, a taxane antineoplastic, inhibits microtubule disassembly, while cladribine, a purine analog, incorporates into DNA and induces apoptosis in dividing and resting lymphocytes. Concurrent use increases the risk of severe neutropenia, thrombocytopenia, and anemia, potentially leading to febrile neutropenia or bleeding complications."
"Cladribine, a purine nucleoside analog with potent immunosuppressive properties, may reduce the pharmacodynamic effects of cardiac glycosides such as acetyldigitoxin. This interaction is hypothesized to occur through cladribine-induced modulation of myocardial cellular signaling pathways that decrease sensitivity to digitalis compounds, potentially leading to reduced inotropic efficacy. Clinically, this could manifest as diminished control of heart rate in patients with atrial fibrillation or worsening heart failure symptoms, particularly in those relying on acetyldigitoxin for rate control or inotropic support."
"The risk or severity of adverse effects can be increased when Pimecrolimus is combined with Cladribine."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about MEXATE vs CLADRIBINE, answered by our medical review team.
MEXATE is a Antineoplastic Agent that works by MEXATE is an antimetabolite that inhibits dihydrofolate reductase (DHFR), reducing tetrahydrofolate synthesis and interfering with DNA, RNA, and protein synthesis. It also inhibits thymidylate synthetase and has immunomodulatory and anti-inflammatory effects.. CLADRIBINE is a Antineoplastic Agent that works by Cladribine is a purine nucleoside analog that is phosphorylated intracellularly to its active triphosphate form, which inhibits DNA synthesis and repair, leading to cell death, particularly in lymphocytes. It also depletes adenosine deaminase (ADA) and accumulates in cells with high deoxycytidine kinase activity.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between MEXATE and CLADRIBINE depend on the specific clinical indication. These are both Antineoplastic Agent agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of MEXATE is: 10-25 mg/m2 orally or intramuscularly once weekly for rheumatoid arthritis; 50 mg/m2 intravenously once weekly for psoriasis; 30-40 mg/m2 intravenously weekly for certain cancers (dose varies by protocol).. The standard adult dose of CLADRIBINE is: 0.09 mg/kg/day IV over 2 hours for 7 consecutive days; or 0.14 mg/kg/day IV over 2 hours for 5 consecutive days (total dose 0.7 mg/kg per course).. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between MEXATE and CLADRIBINE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. MEXATE is classified as Category C. Category X. 1st trimester: High risk of CNS, craniofacial, and skeletal malformations. 2nd and 3rd trimesters: Fetal growth restriction, oligohydramnios, and neonatal pancytopenia.. CLADRIBINE is classified as Category C. FDA Pregnancy Category D. First trimester: Avoid due to known teratogenicity in animal studies (skeletal and visceral malformations) and potential for MDS and AML. Second and third. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.