Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
MEXATE vs CLOLAR
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.
Clolar (clofarabine) is a purine nucleoside antimetabolite that inhibits DNA synthesis and RNA transcription. It is phosphorylated intracellularly to its active triphosphate form, which competes with adenosine triphosphate for incorporation into DNA, leading to chain termination and inhibition of DNA polymerase and ribonucleotide reductase, resulting in apoptosis.
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: Treatment of relapsed or refractory acute lymphoblastic leukemia (ALL) in pediatric patients aged 1 to 21 years.,Off-label: Treatment of acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), chronic myeloid leukemia (CML) in blast crisis.
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).
5 mg/m2 intravenously over 2 hours daily for 5 consecutive days. Repeat every 28 days.
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 approximately 5.2 hours in patients with normal renal function; prolonged in renal impairment (up to 9.8 hours with Cr Cl <60 m L/min) and in elderly; clinical context: supports once-daily dosing adjustment for renal function.
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.
Clofarabine is partially metabolized by deamination via cytidine deaminase (CDA) to inactive 6-keto-clofarabine. Approximately 50-60% of the drug is excreted unchanged in urine.
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: 50-60% as unchanged drug; biliary/fecal: minimal (<5%)
50-60% bound, primarily to albumin.
47% bound to human plasma proteins, primarily albumin.
0.4-0.8 L/kg (total body water). Vd increases with dose, indicating tissue distribution.
Central Vd approximately 172 L/m² (extensive tissue distribution); in L/kg: ~4.6 L/kg (assuming 70 kg patient with BSA 1.73 m²). Clinical meaning: indicates wide distribution into total body water and tissues, exceeding total body water.
Oral: 30-70% (dose-dependent, saturable absorption). Intramuscular: 80-100%. Subcutaneous: approximately 100%.
Intravenous: 100% (only route of administration); oral: not available (no oral formulation).
GFR >50 m L/min: no adjustment; GFR 10-50 m L/min: reduce dose by 50%; GFR <10 m L/min: avoid use.
Cr Cl >= 60 m L/min: no adjustment. Cr Cl 30-59 m L/min: reduce dose by 20%. Cr Cl < 30 m L/min: contraindicated.
Child-Pugh A: 75% of normal dose; Child-Pugh B: 50% of normal dose; Child-Pugh C: contraindicated.
No specific guidelines; use caution in severe hepatic impairment (Child-Pugh class C) and consider dose reduction based on tolerability.
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).
1-21 years: 5 mg/m2 IV over 2 hours daily for 5 days every 28 days; reduce dose by 50% in patients with renal impairment.
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, but monitor renal function closely due to age-related decline and increased risk of toxicity.
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: HEMATOLOGIC TOXICITY, INFECTION, AND HEPATIC TOXICITY. Clolar suppresses bone marrow function, causing severe neutropenia, thrombocytopenia, and anemia. Fatal infections have occurred. Hepatic toxicity, including hepatic failure and death, has been reported. Monitor blood counts and liver function frequently.
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.
Bone marrow suppression: severe neutropenia, thrombocytopenia, and anemia require close monitoring. Infections: serious and fatal infections (bacterial, fungal, viral) may occur. Hepatic toxicity: elevation of liver enzymes, bilirubin, and hepatic veno-occlusive disease. Renal toxicity: increased creatinine, hematuria, and hemolytic uremic syndrome-like reactions. Cardiac toxicity: pericardial effusion, hypotension, and ventricular dysfunction. Tumor lysis syndrome. Hypersensitivity reactions. Use in pregnancy: embryo-fetal toxicity. Vaccination: avoid live vaccines.
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.
Absolute: Hypersensitivity to clofarabine or any component of the formulation. Relative: Severe hepatic impairment (bilirubin >3 mg/d L or transaminases >5x ULN). Severe renal impairment (creatinine clearance <30 m L/min).
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 specific food interactions are documented. However, maintain adequate hydration to reduce risk of nephrotoxicity and tumor lysis syndrome. Avoid grapefruit and grapefruit juice as they may affect metabolism via CYP3A4 (theoretical concern, though clofarabine is primarily renally excreted).
Category X. 1st trimester: High risk of CNS, craniofacial, and skeletal malformations. 2nd and 3rd trimesters: Fetal growth restriction, oligohydramnios, and neonatal pancytopenia.
Clofarabine is contraindicated in pregnancy. Based on its mechanism of action (inhibitor of DNA synthesis) and animal studies, there is a high risk of fetal harm if administered during pregnancy. In the first trimester, there is a significant risk of embryolethality and teratogenicity (structural anomalies). In the second and third trimesters, fetal growth restriction and central nervous system damage may occur. Pregnancy must be excluded before initiation.
Contraindicated. Methotrexate is excreted in human milk; M/P ratio approximately 0.08. Potential for severe neonatal toxicity.
No data available on the excretion of clofarabine into breast milk or its effects on the nursing infant. Due to potential for serious adverse reactions (e.g., myelosuppression, gastrointestinal toxicity), breastfeeding is contraindicated during therapy and for at least 3 months after the last dose. M/P ratio is unknown.
Not applicable; contraindicated in pregnancy. If inadvertent exposure, discontinue and refer for fetal assessment.
There are no established dose adjustments for clofarabine during pregnancy, as use is contraindicated. Physiological changes in pregnancy (e.g., increased plasma volume, altered renal clearance) may affect pharmacokinetics, but no dosing guidelines exist. If inadvertent exposure occurs, immediate discontinuation is recommended and the pregnancy should be managed by a maternal-fetal medicine specialist.
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.
Clolar (clofarabine) is a purine nucleoside analog indicated for pediatric relapsed/refractory acute lymphoblastic leukemia. Key pearls: (1) Monitor for systemic inflammatory response syndrome (SIRS) and capillary leak syndrome; premedicate with corticosteroids. (2) Requires aggressive hydration and allopurinol for tumor lysis prophylaxis. (3) Dose reductions needed for renal impairment (Cr Cl < 60 m L/min). (4) Avoid live vaccines during and after treatment.
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.
Clolar is a chemotherapy drug used to treat a type of leukemia in children that has not responded to other treatments.,You may experience side effects like fever, nausea, vomiting, diarrhea, and skin rashes. Report any signs of infection or unusual bleeding.,Drink plenty of fluids as directed to prevent kidney problems. You may receive IV fluids before and after treatment.,Avoid vaccinations without doctor approval, as live vaccines are not safe during treatment.,This drug can cause severe reactions including organ inflammation and fluid retention; seek immediate medical help if you have difficulty breathing, rapid weight gain, or swelling.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about MEXATE vs CLOLAR, 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.. CLOLAR is a Antineoplastic Agent that works by Clolar (clofarabine) is a purine nucleoside antimetabolite that inhibits DNA synthesis and RNA transcription. It is phosphorylated intracellularly to its active triphosphate form, which competes with adenosine triphosphate for incorporation into DNA, leading to chain termination and inhibition of DNA polymerase and ribonucleotide reductase, resulting in apoptosis.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between MEXATE and CLOLAR 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 CLOLAR is: 5 mg/m2 intravenously over 2 hours daily for 5 consecutive days. Repeat every 28 days.. 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 CLOLAR 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.. CLOLAR is classified as Category C. Clofarabine is contraindicated in pregnancy. Based on its mechanism of action (inhibitor of DNA synthesis) and animal studies, there is a high risk of fetal harm if administered du. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.