Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug, and may not reflect the rates observed in practice.
The most frequently reported adverse reactions include ulcerative stomatitis, leukopenia, nausea, and abdominal distress. Other frequently reported adverse reactions are malaise, fatigue, chills, fever, dizziness, and decreased resistance to infection. Folate deficiency states may increase methotrexate toxicity.
Polyarticular Juvenile Idiopathic Arthritis
The approximate incidences of adverse reactions reported in pediatric patients with JIA treated with oral, weekly doses of methotrexate (5 to 20 mg/m2 /week or 0.1 to 0.65 mg/kg/week) were as follows (virtually all patients were receiving concomitant nonsteroidal anti-inflammatory drugs, and some also were taking low doses of corticosteroids): elevated liver function tests, 14%; gastrointestinal reactions (e.g., nausea, vomiting, diarrhea), 11%; stomatitis, 2%; leukopenia, 2%; headache, 1.2%; alopecia, 0.5%; dizziness, 0.2%; and rash, 0.2%. Although there is experience with dosing up to 30 mg/m2 /week in JIA, the published data for doses above 20 mg/m2 /week are too limited to provide reliable estimates of adverse reaction rates.
Additional adverse reactions which have been identified during postmarketing use of methotrexate are listed below by organ system.
Blood and Lymphatic System Disorders: Suppressed hematopoiesis causing anemia, aplastic anemia, pancytopenia, leukopenia, neutropenia, thrombocytopenia, lymphadenopathy, lymphoproliferative disorders (including reversible), hypogammaglobulinemia
Cardiovascular: Thromboembolic events (including arterial thrombosis, cerebral thrombosis, deep vein thrombosis, retinal vein thrombosis, thrombophlebitis, and pulmonary embolus), pericarditis, pericardial effusion, hypotension
Eye Disorders: Optic neuropathy, transient blindness, blurred vision, ocular irritation, conjunctivitis, xerophthalmia
Gastrointestinal Disorders: Gingivitis, pharyngitis, stomatitis, anorexia, nausea, vomiting, diarrhea, hematemesis, melena, gastrointestinal ulceration and bleeding, enteritis, pancreatitis
Hepatobiliary Disorders: Hepatotoxicity, acute hepatitis, chronic fibrosis and cirrhosis, decreased serum albumin, liver enzyme elevations
Immune System Disorders: Vasculitis, lymphomas, and anaphylactoid reactions
Infections: Fatal opportunistic infections (most commonly Pneumocystis jiroveci pneumonia). There have also been reports of other infections, pneumonia, sepsis, nocardiosis, histoplasmosis, cryptococcosis, Herpes zoster , Herpes simplex hepatitis, and disseminated Herpes simplex
Metabolism: Hyperglycemia and tumor lysis syndrome
Musculoskeletal System: Stress fracture, soft tissue necrosis, osteonecrosis, arthralgia, myalgia, osteoporosis
Nervous System Disorders: Headaches, drowsiness, blurred vision, transient blindness, speech impairment (including dysarthria and aphasia), hemiparesis, paresis and convulsions have also occurred following administration of methotrexate.
Following low doses, there have been reports of transient subtle cognitive dysfunction, mood alteration, unusual cranial sensations, leukoencephalopathy, or encephalopathy.
Renal Disorders: Azotemia, hematuria, proteinuria, cystitis
Reproductive Disorders: Defective oogenesis or spermatogenesis, menstrual dysfunction, loss of libido, impotence, vaginal discharge, gynecomastia
Respiratory Disorders: Pulmonary fibrosis, respiratory failure, chronic interstitial obstructive pulmonary disease, pleuritic pain and thickening alveolitis
Skin Disorders: Erythematous rashes, pruritus, urticaria, photosensitivity, pigmentary changes, alopecia, ecchymosis, telangiectasia, acne, furunculosis, erythema multiforme, toxic epidermal necrolysis, Stevens-Johnson syndrome, skin necrosis, skin ulceration, accelerated nodulosis, and exfoliative dermatitis.
Penicillins may reduce the renal clearance of methotrexate; increased serum concentrations of methotrexate with concomitant hematologic and gastrointestinal toxicity have been observed with methotrexate. Monitor patients accordingly [see Warnings and Precautions (5.1, 5.4)].
Trimethoprim/sulfamethoxazole has been reported to increase bone marrow suppression in patients receiving methotrexate. Monitor patients accordingly [see Warnings and Precautions (5.1)].
The potential for increased hepatotoxicity when methotrexate is administered with other hepatotoxic agents has not been evaluated; however, hepatotoxicity has been reported in such cases. Monitor patients receiving XATMEP with other potential hepatotoxins (e.g., azathioprine, retinoids, and sulfasalazine) for possible signs of hepatotoxicity.
Probenecid may reduce renal elimination of methotrexate. Consider alternative drugs.
The use of nitrous oxide anesthesia potentiates the effect of methotrexate on folate-dependent metabolic pathways, resulting in the potential for increase toxicity. Avoid the simultaneous use of nitrous oxide and methotrexate.
Nonsteroidal Anti-Inflammatory Drugs (NSAIDs), Aspirin, and Steroids
Concomitant administration of some NSAIDs with high dose methotrexate therapy has been reported to elevate and prolong serum methotrexate levels, resulting in deaths from severe hematologic and gastrointestinal toxicity.
Caution should be used when NSAIDs and salicylates are administered concomitantly with lower doses of methotrexate, including XATMEP. These drugs have been reported to reduce the tubular secretion of methotrexate in an animal model and may enhance its toxicity.
Despite the potential interactions, studies of methotrexate in patients with rheumatoid arthritis, including patients with polyarticular juvenile idiopathic arthritis (pJIA), have usually included concurrent use of constant dosage regimens of NSAIDs, without apparent problems. It should be appreciated, however, that the doses used in pJIA (10 mg/m2 /week as starting dose) are somewhat lower than those used in acute lymphoblastic leukemia and that larger doses could lead to unexpected toxicity. Aspirin, NSAIDs, and/or low dose steroids may be continued, although the possibility of increased toxicity with concomitant use of NSAIDs including salicylates has not been fully explored. Steroids may be reduced gradually in patients who respond to methotrexate.
Methotrexate may decrease the clearance of theophylline. Monitor theophylline levels when coadministered with XATMEP.
Based on published reports and methotrexate’s mechanism of action, methotrexate is a teratogen that can cause embryo-fetal toxicity and fetal death when administered to a pregnant woman [see Data and Clinical Pharmacology (12.1)]. In pregnant women with non-malignant disease, XATMEP is contraindicated. Consider the benefits and risks of XATMEP and risks to the fetus when prescribing XATMEP to a pregnant patient with a neoplastic disease. There are no animal data that meet current standards for nonclinical developmental toxicity studies.
The estimated background risk of major birth defects and miscarriage for the indicated populations are unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Published data from cases, literature reviews, and observational studies report that methotrexate exposure during pregnancy is associated with an increased risk of embryo-fetal toxicity and fetal death. Methotrexate exposure during the first trimester of pregnancy is associated with an increased incidence of spontaneous abortions and multiple adverse developmental outcomes, including skull anomalies, facial dysmorphism, central nervous system abnormalities, limb abnormalities, and sometimes cardiac anomalies and intellectual impairment. Adverse outcomes associated with exposure during second and third trimesters of pregnancy include intrauterine growth restriction and functional abnormalities. Because methotrexate is widely distributed and persists in the body for a prolonged period, there is a potential risk to the fetus from preconception methotrexate exposure.
A prospective multicenter study by U.S. and European teratology information services evaluated pregnancy outcomes in women taking methotrexate less than or equal to 30 mg/week after conception. The rate of spontaneous abortion/miscarriage in pregnant women exposed to methotrexate was 42.5% (95% confidence interval [95% CI] 29.2-58.7), which was higher than in unexposed autoimmune disease comparators (22.5%, 95% CI 16.8-29.7) and unexposed nonautoimmune disease comparators (17.3%, 95% CI 13-22.8). Of the live births, the rate of major birth defects in pregnant women exposed to methotrexate after conception was higher than in autoimmune disease comparators (adjusted odds ratio (OR) 1.8 [95% CI 0.6-5.7]) and nonautoimmune disease comparators (adjusted OR 3.1 [95% CI 1.03-9.5]). Major birth defects associated with pregnancies exposed to methotrexate after conception were not always consistent with methotrexate-associated adverse developmental outcomes.
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