Methotrexate (Page 4 of 7)

6.2 Postmarketing Experience

The following adverse reactions have been identified during postapproval use of methotrexate. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure

Cardiovascular: Thromboembolic events (including arterial thrombosis, cerebral thrombosis, deep vein thrombosis, retinal vein thrombosis, thrombophlebitis, and pulmonary embolus), pericarditis, pericardial effusion, hypotension, sudden death

Endocrine: Diabetes

Eye: Optic neuropathy, blurred vision, ocular pain, conjunctivitis, xerophthalmia

Gastrointestinal: Hemorrhagic enteritis, intestinal perforation, gingivitis, pancreatitis, pharyngitis, hematemesis, melena, gastrointestinal ulceration

Hematology: Aplastic anemia, lymphadenopathy, hypogammaglobulinemia

Hepatobiliary: Acute hepatitis, decreased serum albumin, fibrosis, cirrhosis

Immune system: Anaphylaxis, anaphylactoid reactions, vasculitis

Metabolism: Hyperglycemia

Musculoskeletal: Stress fracture, soft tissue and bone necrosis, arthralgia, myalgia, osteoporosis

Nervous system: Headaches, drowsiness, blurred vision, speech impairment (including dysarthria and aphasia), transient cognitive dysfunction, mood alteration, unusual cranial sensations, paresis, encephalopathy, and convulsions.

Renal: Azotemia, hematuria, proteinuria, cystitis

Reproductive: Defective oogenesis or spermatogenesis, loss of libido, impotence, gynecomastia, menstrual dysfunction

Respiratory: Pulmonary fibrosis, respiratory failure, chronic interstitial obstructive pulmonary disease, pleuritic pain and thickening, alveolitis

Skin: Toxic epidermal necrolysis, Stevens-Johnson syndrome, exfoliative dermatitis, skin necrosis, and erythema multiforme, erythematous rashes, pruritus, alopecia, skin ulceration, accelerated nodulosis, urticaria, pigmentary changes, ecchymosis, telangiectasia, photosensitivity, acne, furunculosis

7 DRUG INTERACTIONS

7.1 Effects of Other Drugs on Methotrexate

Drugs that Increase Methotrexate Exposure

Coadministration of methotrexate with the following products may increase methotrexate plasma concentrations, which may increase the risk of methotrexate severe adverse reactions. In some cases, the coadministration of methotrexate with these products may also subsequently reduce active metabolite formation, which may decrease the clinical effectiveness of methotrexate.

Increased organ specific adverse reactions may also occur when methotrexate is coadministered with hepatotoxic or nephrotoxic products.

If coadministration cannot be avoided, monitor closely for methotrexate adverse reactions when coadministered with:

Oral antibiotics (including neomycin)
Oral or intravenous penicillin or sulphonamide antibiotics
Antifolate drugs (e.g., dapsone, pemetrexed, pyrimethamine and sulphonamides)
Aspirin and other nonsteroidal anti-inflammatory drugs
Hepatotoxic products
Highly protein-bound drugs (e.g., oral anticoagulants, phenytoin, salicylates, sulfonamides, sulfonylureas, and tetracyclines)
Proton pump inhibitors
Weak acids (e.g., salicylates)
Probenecid
Nephrotoxic products

Nitrous Oxide

Coadministration of methotrexate with nitrous oxide anesthesia potentiates the effect of methotrexate on folate-dependent metabolic pathways, which may increase the risk of severe methotrexate adverse reactions. Avoid nitrous oxide anesthesia in patients receiving methotrexate. Consider alternative therapies in patients who have received prior nitrous oxide anesthesia.

Folic Acid

Coadministration of methotrexate with folic acid or its derivatives decreases the clinical effectiveness of methotrexate in patients with neoplastic diseases. Methotrexate competes with reduced folates for active transport across cell membranes. Instruct patients to take folic or folinic acid only as directed by their healthcare provider [see Warnings and Precautions (5.10)].

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Risk Summary

Methotrexate tablets are contraindicated in pregnant women with non-neoplastic diseases [see Contraindications (4)].

Based on published reports and its mechanism of action [see Clinical Pharmacology (12.1)] , methotrexate can cause embryo-fetal toxicity and fetal death when administered to a pregnant woman. There are no animal data that meet current standards for nonclinical developmental toxicity studies. Advise pregnant women with neoplastic diseases of the potential risk to a fetus.

In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Data

Human Data

Published data from case reports, 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 evaluated pregnancy outcomes in women taking methotrexate less than or equal to 30 mg/week after conception. The rate of spontaneous abortion and miscarriage in pregnant women exposed to methotrexate was 42% (95% confidence interval [95% CI] 29, 59), which was higher than in unexposed patients with autoimmune disease (22%; 95% CI: 17, 30) and unexposed patients with nonautoimmune disease (17%; 95% CI: 13, 23). Of the live births, the rate of major birth defects in pregnant women exposed to methotrexate after conception was higher than in unexposed patients with autoimmune disease (adjusted odds ratio (OR) 1.8 [95% CI: 0.6, 6]) and unexposed patients with non-autoimmune disease (adjusted OR 3.1 [95% CI: 1, 10]) (2.9%). Major birth defects associated with pregnancies exposed to methotrexate after conception were not always consistent with methotrexate-associated adverse developmental outcomes.

8.2 Lactation

Risk Summary

Limited published literature report the presence of methotrexate in human milk in low amounts, with the highest breast milk to plasma concentration ratio reported to be 0.08:1. There are no data on the effects of methotrexate or its metabolites on the breastfed child or their effects on milk production. Because of the potential for serious adverse reactions in a breastfed child, instruct women not to breastfeed during treatment with methotrexate tablets and for 1 week after the final dose.

8.3 Females and Males of Reproductive Potential

Methotrexate can cause malformations and fetal death at doses less than or equal to the recommended clinical doses [Use in Specific Populations (8.1)].

Pregnancy Testing

Verify the pregnancy status of females of reproductive potential prior to initiating methotrexate tablets [see Contraindications (4), Use in Specific Populations (8.1)].

Contraception

Females

Advise females of reproductive potential to use effective contraception during treatment with methotrexate tablets and for 6 months after the final dose.

Males

Methotrexate can cause chromosomal damage to sperm cells. Advise males with female partners of reproductive potential to use effective contraception during treatment with methotrexate tablets and for 3 months after the final dose.

Infertility

Females

Based on published reports of female infertility after methotrexate, advise females of reproductive potential that methotrexate can cause impairment of fertility and menstrual dysfunction during treatment with methotrexate tablets and after the final dose. It is not known if the infertility may be reversed in all affected females.

Males

Based on published reports of male infertility after methotrexate, advise males that methotrexate can cause oligospermia or infertility during treatment with methotrexate tablets and after the final dose. It is not known if the infertility may be reversed in all affected males.

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