Methotrexate Other names: Amethopterin 4-amino-10-methylfolic acid

Caution should be used when NSAIDs and salicylates are administered concomitantly with methotrexate. These drugs have been reported to reduce the tubular secretion of methotrexate and thereby may enhance its toxicity. Concomitant use of NSAIDs and salicylates has been associated with fatal methotrexate toxicity.

Methotrexate is extensively protein bound and may be displaced by certain drugs such as salicylates, hypoglycaemics, diuretics, sulphonamides, diphenylhydantoins, tetracyclines, so causing a potential for increased toxicity when used concurrently.

Methotrexate is excreted to a significant extent by the kidneys, and therefore should be used with caution in patients with impaired renal function. The health care provider may need to adjust the dose to prevent accumulation of drug. The table below provided recommended starting doses in renally impaired patients; dosing may need further adjustment due to wide intersubject pK variability.

Table 1a. Dose adjustments for methotrexate doses <100 mg/m² in patients with renal impairment:

Table 1b. Dose adjustments for methotrexate doses >100 mg/m² in patients with renal impairment:

Concomitant use of other drugs with nephrotoxic or hepatotoxic potential (including alcohol) should be avoided.

Treatment with more than one DMARD in various regimens is being tried but there is little evidence available to assess benefit. A meta-analysis of 5 different combinations of DMARDs demonstrated that although efficacy might be greater than single DMARDs, toxicity was also increased.

A potential interaction may exist between methotrexate and proton-pump inhibitors (e.g. omeprazole, pantoprazole). Omeprazole may inhibit methotrexate clearance resulting in potentially toxic methotrexate levels.

Use caution when administering high-dose methotrexate to patients receiving proton pump inhibitor (PPI) therapy. Case reports and published population pharmacokinetic studies suggest that concomitant use of some PPIs, such as omeprazole, esomeprazole and pantoprazole, with methotrexate (primarily at high dose), may elevate and prolong serum levels of methotrexate and/or its metabolite hydroxymethotrexate, possibly leading to methotrexate toxicities. In two of these cases, delayed methotrexate elimination was observed when high-dose methotrexate was co-administered with PPIs, but was not observed when methotrexate was co-administered with ranitidine. However, no formal drug interaction studies of methotrexate with ranitidine have been conducted.

Renal tubular transport is also diminished by penicillins; use of these with methotrexate should be carefully monitored.

Methotrexate affects spermatogenesis and oogenesis and may decrease fertility. In humans, methotrexate has been reported to cause oligospermia, menstrual dysfunction and amenorrhoea. These effects appear to be reversible after discontinuation of therapy in most cases.

In oncologic indications, women who are planning to become pregnant are advised to consult a genetic counselling centre, if possible, prior to therapy and men should seek advice about the possibility of sperm preservation before starting therapy as methotrexate can be genotoxic at higher doses.

An increased risk of hepatitis has been reported following the use of methotrexate and the acitretin metabolite, etretinate. Consequently, the concomitant use of methotrexate and acitretin should be avoided.

The administration of amiodarone to patients treated with methotrexate for psoriasis has caused ulcerated skin lesions.

L-asparaginase antagonizes the activity of methotrexate.

Methotrexate is extensively protein bound and may be displaced by certain drugs such as chloramphenicol and p-aminobenzoic acid, and the acidic anti-inflammatory agents, so causing a potential for increased toxicity when used concurrently.

Enhance the toxicity of methotrexate when co-administered with cyclosporine, retinoids and corticosteroids.

Renal tubular secretion of methotrexate is reduced by ciprofloxacin. The use of methotrexate with this medicine should be carefully monitored.

When intravenous methotrexate is given concomitantly with intravenous cytarabine, the risk of serious neurological adverse events such as headache, paralysis, coma, and stroke-like episodes may be increased.

Concomitant use of methotrexate with leflunomide may increase the risk of pancytopenia.

Methotrexate may increase the bioavailability of mercaptopurine by interference with first-pass metabolism.

The use of nitrous oxide anaesthesia potentiates the effect of methotrexate on folate metabolism, yielding increased toxicity such as severe unpredictable myelosuppression, stomatitis and neurotoxicity. Severe neurotoxicity has particularly been reported with intrathecal administration of methotrexate following nitrous oxide anaesthesia. While this effect can be reduced by administering calcium folinate, the concomitant use of nitrous oxide and methotrexate should be avoided.

Renal tubular transport is also diminished by probenecid; use of these with methotrexate should be carefully monitored.

Concomitant application of methotrexate and theophylline can reduce theophylline clearance.

Severe bone marrow depression has been reported following the concurrent use of methotrexate and co-trimoxazole or trimethoprim. Concurrent use should probably be avoided.

Vincristine and vinblastine increase the cellular uptake of methotrexate.

Vitamin preparations containing folic acid or its derivatives may decrease the effectiveness of methotrexate.

Methotrexate given concomitantly with radiotherapy may increase the risk of soft tissue necrosis and osteonecrosis.

Acute or chronic interstitial pneumonitis, often associated with blood eosinophilia, may occur and deaths have been reported. Symptoms typically include dyspnoea, cough (especially a dry non-productive cough), thoracic pain and fever for which patients should be monitored at each follow-up visit. Patients should be informed of the risk of pneumonitis and advised to contact their doctor immediately should they develop persistent cough or dyspnoea.

In addition, pulmonary alveolar haemorrhage has been reported with methotrexate used in rheumatologic and related indications. This event may also be associated with vasculitis and other comorbidities. Prompt investigations should be considered when pulmonary alveolar haemorrhage is suspected to confirm the diagnosis.

Methotrexate should be withdrawn from patients with pulmonary symptoms and a thorough investigation should be made to exclude infection. If methotrexate induced lung disease is suspected treatment with corticosteroids should be initiated and treatment with methotrexate should not be restarted.

When a patient presents with pulmonary symptoms, the possibility of Pneumocystis carinii pneumonia should be considered.

Methotrexate is given with special care to patients with a history of ulcer or ulcerative colitis.

Methotrexate is contraindicated during pregnancy in non-oncological indications.

Both men and women receiving methotrexate should be informed of the potential risk of adverse effects on reproduction. Women of childbearing potential should be fully informed of the potential hazard to the foetus should they become pregnant during methotrexate therapy. In cancer chemotherapy, methotrexate should not be used in pregnant women or women of childbearing potential who might become pregnant unless the potential benefits to the mother outweigh the possible risks to the foetus.

If pregnancy occurs during treatment with methotrexate and up to six months thereafter, medical advice should be given regarding the risk of harmful effects on the child associated with treatment and ultrasonography examinations should be performed to confirm normal foetal development.

In animal studies, methotrexate has shown reproductive toxicity, especially during the first trimester. Methotrexate has been shown to be teratogenic to humans; it has been reported to cause foetal death, miscarriages and/or congenital abnormalities (e.g. craniofacial, cardiovascular, central nervous system and extremity-related).

Methotrexate is a powerful human teratogen, with an increased risk of spontaneous abortions, intrauterine growth restriction and congenital malformations in case of exposure during pregnancy.

Spontaneous abortions have been reported in 42.5% of pregnant women exposed to low-dose methotrexate treatment (less than 30 mg/week), compared to a reported rate of 22.5% in disease-matched patients treated with drugs other than methotrexate.

Major birth defects occurred in 6.6% of live births in women exposed to low-dose methotrexate treatment (less than 30 mg/week) during pregnancy, compared to approximately 4% of live births in in disease-matched patients treated with drugs other than methotrexate.

Insufficient data is available for methotrexate exposure during pregnancy higher than 30 mg/week, but higher rates of spontaneous abortions and congenital malformations are expected, in particular at doses commonly used in oncologic indications.

When methotrexate was discontinued prior to conception, normal pregnancies have been reported.

When used in oncological indications, methotrexate should not be administered during pregnancy in particular during the first trimester of pregnancy. In each individual case the benefit of treatment must be weighed up against the possible risk to the foetus. If the drug is used during pregnancy or if the patient becomes pregnant while taking methotrexate, the patient should be informed of the potential risk to the foetus.

Methotrexate is excreted in human milk. Because of the potential for serious adverse reactions in breast-fed infants, methotrexate is contraindicated during breast-feeding. Therefore breast-feeding must be discontinued prior and during administration.

Women of childbearing potential/Contraception in males and females

Women must not get pregnant during methotrexate therapy, and effective contraception must be used during treatment with methotrexate and at least 6 months thereafter. Prior to initiating therapy, women of childbearing potential must be informed of the risk of malformations associated with methotrexate and any existing pregnancy must be excluded with certainty by taking appropriate measures, e.g. a pregnancy test. During treatment pregnancy tests should be repeated as clinically required (e.g. after any gap of contraception). Female patients of reproductive potential must be counselled regarding pregnancy prevention and planning.

Contraception in males

It is not known if methotrexate is present in semen. Methotrexate has been shown to be genotoxic in animal studies, such that the risk of genotoxic effects on sperm cells cannot completely be excluded. Limited clinical evidence does not indicate an increased risk of malformations or miscarriage following paternal exposure to low-dose methotrexate (less than 30 mg/week). For higher doses, there is insufficient data to estimate the risks of malformations or miscarriage following paternal exposure.

As precautionary measures, sexually active male patients or their female partners are recommended to use reliable contraception during treatment of the male patient and for at least 6 months after cessation of methotrexate. Men should not donate semen during therapy or for 6 months following discontinuation of methotrexate.

Fertility

Methotrexate affects spermatogenesis and oogenesis and may decrease fertility. In humans, methotrexate has been reported to cause oligospermia, menstrual dysfunction and amenorrhoea. These effects appear to be reversible after discontinuation of therapy in most cases.

In oncologic indications, women who are planning to become pregnant are advised to consult a genetic counselling centre, if possible, prior to therapy and men should seek advice about the possibility of sperm preservation before starting therapy as methotrexate can be genotoxic at higher doses.

Central nervous system symptoms, such as fatigue and dizziness, can occur during treatment with methotrexate which have minor or moderate influence on the ability to drive and use machines.

Oral administration

In general, the incidence and severity of side effects are considered to be dose-related.

In the antineoplastic treatment, myelosuppression and mucositis are the predominant dose-limiting toxic effects of methotrexate. The severity of these reactions depends on the dose, mode and duration of application of methotrexate. Mucositis generally appears about 3 to 7 days after methotrexate application, leucopenia and thrombocytopenia follow a few days later. In patients with unimpaired elimination mechanisms, myelosuppression and mucositis are generally reversible within 14 to 28 days.

Most serious adverse reactions of methotrexate include bone marrow suppression, pulmonary toxicity, hepatotoxicity, renal toxicity, neurotoxicity, thromboembolic events, anaphylactic shock and StevensJohnson syndrome.

Most frequently (very common) observed adverse reactions of methotrexate include gastrointestinal disorders (e.g. stomatitis, dyspepsia, abdominal pain, nausea, loss of appetite) and abnormal liver function tests (e.g. increased alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), bilirubin, alkaline phosphatase). Other frequently (common) occurring adverse reactions are leukopenia, anaemia, thrombopenia, headache, tiredness, drowsiness, pneumonia, interstitial alveolitis/pneumonitis often associated with eosinophilia, oral ulcers, diarrhoea, exanthema, erythema and pruritus.

The occurrence and severity of adverse reactions depend on dosage level and frequency of administration of methotrexate. However, as severe adverse reactions may occur even at low doses, it is essential for the treating physician to monitor patients closely.

Most adverse reactions are reversible if they are detected early. If such adverse reactions occur, the dose should either be reduced or treatment discontinued and appropriate countermeasures taken. Methotrexate therapy should only be resumed with particular caution, after careful consideration of the need for treatment and with increased vigilance for the possible recurrence of toxicity.

Tabulated list of adverse reactions

Frequencies in the table are defined according to the MedDRA convention: Very common (≥1/10) Common (≥ 1/100 to <1/10) Uncommon (≥1/1,000 to < 1/100) Rare (≥1/10,000 to <1/1,000) Very rare (<1/10,000) Not known (cannot be estimated from the available data)

Within each frequency grouping, adverse reactions are presented in order of decreasing seriousness.

¹ can be reversible
² Lymphoma/Lymphoproliferative disorders: there have been reports of individual cases of lymphoma and other lymphoproliferative disorders which subsided in a number of cases once treatment with methotrexate had been discontinued.
³ has been reported for methotrexate used in rheumatologic and related indications
⁴ see remarks on liver biopsy

Paediatric population

Frequency, type and severity of adverse reactions in children and adolescents are expected to be the same as in adults.

Description of selected adverse reactions

Lymphoma/Lymphoproliferative disorders: there have been reports of individual cases of lymphoma and other lymphoproliferative disorders which subsided in a number of cases once treatment with methotrexate had been discontinued.

Intramuscular / Intravenous / Intraarterial / Intrathecal administration

The most common adverse reactions include ulcerative stomatitis, leukopenia, nausea and abdominal distress. Although very rare, anaphylactic reactions to methotrexate have occurred. Others reported are malaise, undue fatigue, chills and fever, dizziness and decreased resistance to infection. In general, the incidence and severity of side effects are considered to be dose-related. Adverse reactions as reported for the various systems are as follows:

Skin: Severe, occasionally fatal, dermatologic reactions including erythema multiforme, Stevens-Johnson syndrome, skin necrosis, exfoliative dermatitis, epidermal necrolysis. Erythematous rashes, pruritus, urticaria, dermatitis, photosensitivity, pigmentary changes, alopecia, ecchymosis, telangiectasia, acne, furunculosis. Lesions of psoriasis may be aggravated by concomitant exposure to ultraviolet radiation. Skin ulceration in psoriatic patients and rarely painful erosion of psoriatic plaques have been reported. The recall phenomenon has been reported in both radiation and solar damaged skin.

Blood: Bone marrow depression, leukopenia, thrombocytopenia, anaemia, hypogammaglobulinaemia, haemorrhage from various sites, septicaemia, lymphoproliferative disorders (frequency very rare).

Alimentary System: Gingivitis, pharyngitis, stomatitis, mucositis, anorexia, vomiting, diarrhoea, haematemesis, melaena, gastrointestinal ulceration and bleeding, pancreatitis, enteritis, hepatic toxicity resulting in active liver atrophy, necrosis, fatty metamorphosis, periportal fibrosis, or hepatic cirrhosis. In rare cases the effect of methotrexate on the intestinal mucosa has led to malabsorption or toxic megacolon.

Hepatic: Hepatic toxicity resulting in significant elevations of liver enzymes, acute liver atrophy, necrosis, fatty metamorphosis, hepatitis, periportal fibrosis or cirrhosis or death may occur, usually following chronic administration.

Urogenital System: Renal failure, azotaemia, cystitis, haematuria, defective oogenesis or spermatogenesis, transient oligospermia, menstrual dysfunction, infertility, abortion, foetal defects, severe nephropathy. Vaginitis, vaginal ulcers, cystitis, haematuria and nephropathy have also been reported.

Pulmonary System: Acute or chronic interstitial pneumonitis, often associated with blood eosinophilia, may occur and deaths have been reported. Acute pulmonary oedema has also been reported after oral and intrathecal use. Pulmonary fibrosis is rare. A syndrome consisting of pleuritic pain and pleural thickening has been reported following high doses. Frequency Not Known: Pulmonary alveolar haemorrhage*.

* (has been reported for methotrexate used in rheumatologic and related indications)

Central Nervous System: Headaches, drowsiness, blurred vision, aphasia, cognitive disorder, hemiparesis and convulsions have occurred possibly related to haemorrhage or to complications from intraarterial catheterization. Convulsion, paresis, Guillain-Barre syndrome and increased cerebrospinal fluid pressure have followed intrathecal administration.

Other reactions related to, or attributed to the use of methotrexate such as pneumonitis, metabolic changes, precipitation of diabetes, osteoporotic effects, abnormal changes in tissue cells and even sudden death have been reported.

There have been reports of leukoencephalopathy following intravenous methotrexate in high doses, or low doses following cranial-spinal radiation.

Cardiac disorders: Pericarditis, pericardial effusion.

Ear disorders: Tinnitus.

Eye disorders: Conjunctivitis.

Infections and infestations: Opportunistic infections (sometimes fatal e.g. fatal sepsis) have also been reported in patients receiving methotrexate therapy for neoplastic and non-neoplastic diseases, Pneumocystis carinii pneumonia being the most common. Other reported infections include, pneumonia, nocardiosis, histoplasmosis, cryptococcosis, Herpes Zoster, Herpes Simplex, hepatitis and cytomegalovirus infection, including cytomegaloviral pneumonia.

Musculoskeletal and connective tissue disorders: Arthralgia/myalgia, Osteonecrosis of jaw (secondary to lymphoproliferative disorders) - frequency unknown.

Psychiatric disorders: Mood altered

Vascular disorder: Vasculitis, hypotension, thromboembolic events (e.g. thrombophlebitis, pulmonary embolism, arterial, cerebral, deep vein or retinal vein thrombosis).

Adverse reactions following intrathecal methotrexate are generally classified into three groups, acute, subacute, and chronic. The acute form is a chemical arachnoiditis manifested by headache, back or shoulder pain, nuchal rigidity, and fever. The subacute form may include paresis, usually transient, paraplegia, nerve palsies, and cerebellar dysfunction. The chronic form is a leukoencephalopathy manifested by irritability, confusion, ataxia, spasticity, occasionally convulsions, dementia, somnolence, coma, and rarely, death. There is evidence that the combined use of cranial radiation and intrathecal methotrexate increases the incidence of leukoencephalopathy.

Additional reactions related to or attributed to the use of methotrexate such as osteoporosis, abnormal (usually ‘megaloblastic’) red cell morphology, precipitation of diabetes, other metabolic changes, and sudden death have been reported.

Subcutaneous administration

Summary of the safety profile

Most serious adverse reactions of methotrexate include bone marrow suppression, pulmonary toxicity, hepatotoxicity, renal toxicity, neurotoxicity, thromboembolic events, anaphylactic shock and Stevens-Johnson syndrome.

Most frequently (very common) observed adverse reactions of methotrexate include gastrointestinal disorders e.g. stomatitis, dyspepsia, abdominal pain, nausea, loss of appetite and abnormal liver function tests e.g. increased ALAT, ASAT, bilirubin, alkaline phosphatase. Other frequently (common) occurring adverse reactions are leukopenia, anaemia, thrombopenia, headache, tiredness, drowsiness, pneumonia, interstitial alveolitis/pneumonitis often associated with eosinophilia, oral ulcers, diarrhoea, exanthema, erythema and pruritus.

Tabulated list of adverse reactions

The most relevant undesirable effects are suppression of the haematopoietic system and gastrointestinal disorders.

The following headings are used to organise the undesirable effects in order of frequency:

Very common (≥1/10), common (≥1/100 to <1/10), uncommon (≥1/1,000 to <1/100), rare (≥1/10,000 to <1/1,000), very rare (<1/10,000), not known (cannot be estimated from the available data)

Infections and infestations

Uncommon: Pharyngitis.

Rare: Infection (incl. reactivation of inactive chronic infection), sepsis, conjunctivitis.

Neoplasms benign, malignant and unspecified (including cysts and polyps)

Very rare: Lymphoma (see “description” below).

Blood and lymphatic system disorders

Common: Leukopenia, anaemia, thrombopenia.

Uncommon: Pancytopenia.

Very rare: Agranulocytosis, severe courses of bone marrow depression, lymphoproliferative disorders (see “description” below).

Not known: Eosinophilia

Immune system disorders

Rare: Allergic reactions, anaphylactic shock, hypogammaglobulinaemia.

Metabolism and nutrition disorders

Uncommon: Precipitation of diabetes mellitus.

Psychiatric disorders

Uncommon: Depression, confusion.

Rare: Mood alterations.

Nervous system disorders

Common: Headache, tiredness, drowsiness.

Uncommon: Dizziness.

Very rare: Pain, muscular asthenia or paraesthesia in the extremities, changes in sense of taste (metallic taste), convulsions, meningism, acute aseptic meningitis, paralysis.

Not known: Encephalopathy/leukoencephalopathy.

Eye disorders

Rare: Visual disturbances.

Very rare: Impaired vision, retinopathy.

Cardiac disorders

Rare: Pericarditis, pericardial effusion, pericardial tamponade.

Vascular disorders

Rare: Hypotension, thromboembolic events.

Respiratory, thoracic and mediastinal disorders

Common: Pneumonia, interstitial alveolitis/pneumonitis often associated with eosinophilia. Symptoms indicating potentially severe lung injury (interstitial pneumonitis) are: dry, not productive cough, short of breath and fever.

Rare: Pulmonary fibrosis, Pneumocystis carinii pneumonia, shortness of breath and bronchial asthma, pleural effusion.

Not known: Epistaxis, pulmonary alveolar haemorrhage.

Gastrointestinal disorders

Very common: Stomatitis, dyspepsia, nausea, loss of appetite, abdominal pain.

Common: Oral ulcers, diarrhoea.

Uncommon: Gastrointestinal ulcers and bleeding, enteritis, vomiting, pancreatitis.

Rare: Gingivitis.

Very rare: Haematemesis, haematorrhea, toxic megacolon.

Hepatobiliary disorders

Very common: Abnormal liver function tests (increased ALAT, ASAT, alkaline phosphatase and bilirubin).

Uncommon: Cirrhosis, fibrosis and fatty degeneration of the liver, decrease in serum albumin.

Rare: Acute hepatitis.

Very rare: Hepatic failure.

Skin and subcutaneous tissue disorders

Common: Exanthema, erythema, pruritus.

Uncommon: Photosensitisation, loss of hair, increase in rheumatic nodules, skin ulcer, herpes zoster, vasculitis, herpetiform eruptions of the skin, urticaria.

Rare: Increased pigmentation, acne, petechiae, ecchymosis, allergic vasculitis.

Very rare: Stevens-Johnson syndrome, toxic epidermal necrolysis (Lyell’s syndrome), increased pigmentary changes of the nails, acute paronychia, furunculosis, telangiectasia.

Musculoskeletal and connective tissue disorders

Uncommon: Arthralgia, myalgia, osteoporosis.

Rare: Stress fracture.

Not known: Osteonecrosis of jaw (secondary to lymphoproliferative disorders).

Renal and urinary disorders

Uncommon: Inflammation and ulceration of the urinary bladder, renal impairment, disturbed micturition.

Rare: Renal failure, oliguria, anuria, electrolyte disturbances.

Not known: Proteinuria.

Reproductive system and breast disorders

Uncommon: Inflammation and ulceration of the vagina.

Very rare: Loss of libido, impotence, gynaecomastia, oligospermia, impaired menstruation, vaginal discharge.

General disorders and administration site conditions

Rare: Fever, wound-healing impairment.

Not known: Asthenia.

Description of selected adverse reactions

The appearance and degree of severity of undesirable effects depends on the dose level and the frequency of administration. However, as severe undesirable effects can occur even at lower doses, it is indispensable that patients are monitored regularly by the doctor at short intervals.

Lymphoma/Lymphoproliferative disorders: there have been reports of individual cases of lymphoma and other lymphoproliferative disorders which subsided in a number of cases once treatment with methotrexate had been discontinued.

Subcutaneous application of methotrexate is locally well tolerated. Only mild local skin reactions (such as burning sensations, erythema, swelling, discolouration, pruritus, severe itching, pain) were observed, decreasing during therapy.