WARNINGS
General
Methotrexate must be used only by physicians experienced in antimetabolite chemotherapy.
Because of the possibility of serious toxic reactions (which can be fatal), methotrexate should be used only in neoplastic diseases (as indicated), or in patients with severe, recalcitrant, disabling psoriasis that is not adequately responsive to other forms of therapy. The patient should be informed by the physician of the risks involved and should be under a physician's constant supervision.
In all instances where the use of methotrexate is considered for chemotherapy, the physician must evaluate the need and usefulness of the drug against the risks of toxic effects or adverse reactions. Most such adverse reactions are reversible if detected early. When such effects or reactions do occur, the drug should be reduced in dosage or discontinued and appropriate corrective measures should be taken according to the clinical judgement of the physician. Reinstitution of methotrexate therapy should be carried out with caution, with adequate consideration of further need for the drug and alertness as to the possible recurrence of toxicity
The prescriber should specify the day of intake on the prescription for patients being treated for psoriasis. The prescriber should make sure that patients being treated for psoriasis understand that methotrexate should only be taken once a week. Patients should be instructed on the importance of adhering to the once-weekly intakes, and that mistaken daily use of the recommended dose has led to fatal toxicity.
Pulmonary
Acute or chronic interstitial pneumonitis and pleural effusion, often associated with blood eosinophilia, may occur at any time during therapy and has been reported at low doses. It is not always fully reversible, 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.
Pulmonary signs and symptoms, e.g. a dry non-productive cough, fever, cough, chest pain, dyspnoea, hypoxemia, and an infiltrate on chest X-ray, or a nonspecific pneumonitis occurring during methotrexate therapy, may be indicative of a potentially dangerous lesion. Methotrexate should be withdrawn from patients with pulmonary symptoms and a thorough investigation should be made to exclude infection (including pneumonia). If methotrexate induced lung disease is suspected treatment with corticosteroids should be initiated and treatment with methotrexate should not be restarted. Methotrexate-induced pneumonitis can occur at all doses.
Potentially fatal opportunistic infections, including Pneumocystis jirovecii pneumonia, may occur with methotrexate therapy. When a patient presents with pulmonary symptoms, the possibility of Pneumocystis jirovecii pneumonia should be considered.
Pulmonary function tests may be useful if lung disease (e.g. interstitial pneumonitis) is suspected, especially if baseline measurements are available.
Pleural effusions and ascites should be drained prior to initiation of methotrexate therapy.
Methotrexate toxicity
Methotrexate has the potential for serious, sometimes fatal toxicity. The toxic effects may be related in frequency and severity to the dose or frequency of administration but have been seen at all doses. Because the toxic reactions can occur at any time during therapy, the patients have to be observed closely and must be informed of the potential benefits and risks in the use of methotrexate (including the early signs and symptoms of toxicity), the need to see their physician promptly if they occur, and of the need for close follow up, including periodic laboratory tests to monitor toxicity (see also 'Laboratory Monitoring'). Folate deficiency states may increase methotrexate toxicity. If acute methotrexate toxicity occurs, patients may require folinic acid.
It should be noted that intrathecal doses are transported into the cardiovascular system and may give rise to systemic toxicity. Systemic toxicity of methotrexate may also be enhanced in patients with renal dysfunction, ascites, or other effusions due to prolongation of serum half-life. Blood counts should be monitored closely.
High-dose and low-dose regimens
The use of methotrexate high-dose regimens (≥500 mg/m2) requires meticulous care (see section 4.2 for pre-hydration instructions and folinic acid rescue).
Malignant lymphomas may occur in patients receiving low-dose methotrexate. These lymphomas may regress following withdrawal of methotrexate without requiring treatment.
Neurological
Cases of progressive multifocal leukoencephalopathy (PML) have been reported in patients receiving methotrexate, mostly in combination with other immunosuppressive medication. PML can be fatal and should be considered in the differential diagnosis in immunosuppressed patients with new onset or worsening neurological symptoms.
There have been reports of leukoencephalopathy following intravenous administration of methotrexate to patients who have had craniospinal irradiation. See 'Paediatric use' for specific warnings. Symptomatic patients were commonly noted to have leukoencephalopathy and/or microangiopathic calcifications on diagnostic imaging studies.
Chronic leukoencephalopathy has also been reported in patients who received repeated doses of high-dose methotrexate with folinic acid rescue even without cranial irradiation. There are also reports of leukoencephalopathy in patients who received oral methotrexate. Discontinuation of methotrexate does not always result in complete recovery.
A transient acute neurologic syndrome has been observed in patients treated with high-dosing regimens. Manifestations of this neurologic syndrome may include behavioural abnormalities, focal sensorimotor signs, including transient blindness, and abnormal reflexes. The exact cause is unknown.
After the intrathecal use of methotrexate, the central nervous system toxicity that may occur can be classified as follows:
- acute chemical arachnoiditis manifested by e.g. headache, back pain, nuchal rigidity, and fever
- sub-acute myelopathy characterised by e.g. paraparesis/paraplegia associated with involvement with one or more spinal nerve roots
- chronic leukoencephalopathy manifested by e.g. confusion, irritability, somnolence, ataxia, dementia, seizures, and coma.
This central nervous system toxicity can be progressive and even fatal. There is evidence that the combined use of cranial radiation and intrathecal methotrexate increases the incidence of leukoencephalopathy. Signs of neurotoxicity (meningeal irritation, transient or permanent paresis, encephalopathy) should be monitored following intrathecal administration of methotrexate.
Intrathecal and intravenous administration of methotrexate may also result in acute encephalitis and acute encephalopathy with fatal outcome.
There have been reports of patients with periventricular CNS lymphoma who developed cerebral herniation with the administration of intrathecal methotrexate.
Cases of severe neurological adverse reactions that ranged from headache to paralysis, coma and stroke-like episodes have been reported mostly in juveniles and adolescents given intrathecal methotrexate in combination with intravenous cytarabine.
Proton-pump inhibitors
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.
Psoriasis
Deaths have been reported with the use of methotrexate in the treatment of psoriasis.
In the treatment of psoriasis, methotrexate should be restricted to severe recalcitrant, disabling psoriasis which is not adequately responsive to other forms of therapy, but only when the diagnosis has been established by biopsy and/or after dermatological consultation.
Hepatic
Methotrexate may be hepatotoxic, particularly at high dosage or with prolonged therapy. Liver atrophy, necrosis, cirrhosis, fatty changes, and periportal fibrosis have been reported.
Liver function tests: Treatment should not be initiated or should be discontinued if there are persistent or significant abnormalities in liver function tests, other non-invasive investigations of hepatic fibrosis, or liver biopsies.
Temporary increases in transaminases to two or three times the upper limit of normal have been reported in patients at a frequency of 13-20%. Persistent elevation of liver enzymes and/or decrease in serum albumin may be indicative for severe hepatotoxicity. In the event of a persistent increase in liver enzymes, consideration should be given to reducing the dose or discontinuing therapy.
Histological changes, fibrosis and more rarely liver cirrhosis may not be preceded by abnormal liver function tests. There are instances in cirrhosis where transaminases are normal. Therefore, non-invasive diagnostic methods for monitoring of liver condition should be considered, in addition to liver function tests. Liver biopsy should be considered on an individual basis taking into account the patient's comorbidities, medical history and the risks related to biopsy. Risk factors for hepatotoxicity include excessive prior alcohol consumption, persistent elevation of liver enzymes, history of liver disease, family history of hereditary liver disorders, diabetes mellitus, obesity and previous contact with hepatotoxic drugs or chemicals and prolonged methotrexate treatment.
Additional hepatotoxic medicinal products should not be given during treatment with methotrexate unless clearly necessary. Alcohol consumption should be avoided (see sections 4.5). Closer monitoring of liver enzymes should be undertaken in patients concomitantly taking other hepatotoxic medicinal products.
Increased caution should be exercised in patients with insulin-dependent diabetes mellitus, as during methotrexate therapy, liver cirrhosis developed in isolated cases without any elevation of transaminases.
Methotrexate has caused reactivation of hepatitis B infection or worsening of hepatitis C infections, in some cases resulting in death. Some cases of hepatitis B reactivation have occurred after discontinuation of methotrexate. Clinical and laboratory evaluation should be performed to evaluate pre-existing liver disease in patients with prior hepatitis B or C infections. Based on these evaluations, treatment with methotrexate may not be appropriate for some patients.
Renal
Methotrexate therapy in patients with impaired renal function should be undertaken with extreme caution because impairment of renal function will decrease methotrexate elimination.
Renal function should be monitored by renal function tests and urinalyses. If serum creatinine levels are increased, the dose should be reduced. If creatinine clearance is less than 30 ml/min, treatment with methotrexate should not be given. If creatinine clearance is less than 60 ml/min, methotrexate doses >100 mg/m2 not be given (see section 4.2 and 4.3).
Treatment with methotrexate doses of >100 mg/m2 should not be initiated at urinary pH values of less than 7.0. Alkalinisation of the urine must be tested by repeated pH monitoring (value greater than or equal to 6.8) for at least the first 24 hours after the administration of methotrexate is started.
Methotrexate may cause renal damage that may lead to acute renal failure. Close attention to renal function including adequate hydration, urine alkalinisation, and measurement of serum methotrexate and renal function are recommended.
As methotrexate is eliminated mainly via the kidney's, increased concentrations are to be expected in the presence of renal impairment, which may result in severe adverse reactions.
If there is the possibility of renal impairment (e.g. in elderly subjects), monitoring should take place at shorter intervals. This applies in particular when medicinal products that affect the elimination of methotrexate, or that cause kidney damage (e.g. non-steroidal anti-inflammatory drugs (NSAIDs)) or that can potentially lead to impairment of haematopoiesis, are administered concomitantly.
If risk factors such as renal function disorders, including mild renal impairment, are present, combined administration with NSAIDs is not recommended. Dehydration may also intensify the toxicity of methotrexate.
Concomitant use of proton pump inhibitors (PPIs) and high dose methotrexate should be avoided, especially in patients with renal impairment.
Skin Reactions
Severe, occasionally fatal, cutaneous or sensitivity reactions (e.g., toxic epidermal necrolysis, Stevens-Johnson syndrome, exfoliative dermatitis, skin necrosis, erythema multiforme, vasculitis and extensive herpetiform skin eruptions) may occur after the administration of methotrexate and recovery usually ensures after discontinuation of the therapy.
Photosensitivity: Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking methotrexate (see section 4.8). Exposure to intense sunlight or UV rays should be avoided unless medically indicated. Patients should use adequate sun-protection to protect themselves from intense sunlight.
Lesions of psoriasis may be aggravated by concomitant exposure to ultraviolet radiation.
Methotrexate given concomitantly with radiotherapy may increase the risk of soft tissue necrosis and osteonecrosis.
Radiation dermatitis and sunburn may be “recalled” by the use of methotrexate.
Other
Diarrhoea and ulcerative stomatitis are frequent toxic effects and require interruption of therapy, otherwise haemorrhagic enteritis and death from intestinal perforation may occur.
Methotrexate affects gametogenesis during the period of its administration and may result in decreased fertility which is thought to be reversible on discontinuation of therapy. Conception should be avoided during the period of methotrexate administration and for at least 6 months thereafter. Patients and their partners should be advised to this effect. See 'Fertility and reproduction'.
Methotrexate has some immunosuppressive activity and immunological responses to concurrent vaccination may be decreased. The immunosuppressive effect of methotrexate should be taken into account when immune responses of patients are important or essential. Immunisation with live virus vaccines is generally not recommended.
Deaths have been reported with the use of methotrexate. Serious adverse reactions including deaths have been reported with concomitant administration of methotrexate (usually in high doses) along with some NSAIDs (see section 4.5).
Concomitant administration of folate antagonists such as trimethoprim/sulphamethoxazole has been reported to cause an acute megaloblastic pancytopenia in rare instances.
Like other cytotoxic drugs, methotrexate may induce “tumour lysis syndrome” in patients with rapidly growing tumours. In rare cases, following intrathecal administration, tumour lysis syndrome has been observed. Appropriate supportive and pharmacologic measures may prevent or alleviate this complication.
Special populations
Paediatric use
Overdose by intravenous and intrathecal miscalculation of dosage (particularly in juveniles) has occurred. Special attention must be given to dose calculation (see section 4.2).
Serious neurotoxicity frequently manifested as generalised or focal seizures has been reported with unexpectedly increased frequency among paediatric patients with acute lymphoblastic leukaemia who were treated with intravenous methotrexate (1 g/m2).
Use in the elderly
Methotrexate should be used with extreme caution in elderly patients. Elderly patients should be monitored closely for early signs of methotrexate toxicity. Dose reduction should be considered in elderly patients due to reduced liver and kidney function as well as lower folate reserves which occur with increased age (see section 4.2).
PRECAUTIONS
Methotrexate toxicity and folate rescue
Serum methotrexate level monitoring can significantly reduce toxicity and mortality by allowing the adjustment of methotrexate dosing and the implementation of appropriate rescue measures (see section 4.2).
Patients subject to the following conditions are predisposed to developing elevated or prolonged methotrexate levels and benefit from routine monitoring of levels: pleural effusion, ascites, gastrointestinal tract obstruction, previous cisplatin therapy, dehydration, aciduria and impaired renal function.
Some patients may have delayed methotrexate clearance in the absence of these features. It is important that patients be identified within 48 hours since methotrexate toxicity may not be reversible if adequate folinic acid rescue is delayed for more than 42 to 48 hours.
The method of monitoring methotrexate concentrations varies from institution to institution. Monitoring of methotrexate concentrations should include determination of a methotrexate level at 24, 48, or 72 hours, and assessment of the rate of decline in methotrexate concentrations (to determine how long to continue folinic acid rescue).
Methotrexate has a high potential toxicity, usually dose related, and should be used only by physicians experienced in antimetabolite chemotherapy, in patients under their constant supervision. The physician should be familiar with the various characteristics of the drug and its established clinical usage.
Fertility and reproduction
Fertility
Methotrexate has been reported to cause impairment of fertility, oligospermia, menstrual dysfunction and amenorrhoea in humans, during and for a short period after cessation of therapy, affecting spermatogenesis and oogenesis during the period of its administration - effects that appear to be reversible on discontinuing therapy. In addition, methotrexate causes embryotoxicity, abortion and foetal defects in humans.
Teratogenicity – Reproductive risk
Methotrexate causes embryotoxicity, abortion and foetal malformations in humans. Therefore, the possible risks of effects on reproduction, pregnancy loss and congenital malformations should be discussed with female patients of childbearing potential (see section 4.6). The absence of pregnancy must be confirmed before methotrexate is used. If women of a sexually mature age are treated, effective contraception must be used during treatment and for at least 6 months after. Pregnant psoriatic patients should not receive methotrexate.
For contraception advice for men see section 4.6.
Haematologicical
Patients undergoing therapy should be subject to appropriate supervision so that signs or symptoms of possible toxic effects or adverse reactions may be detected and evaluated with minimal delay.
Methotrexate can suppress haematopoiesis and cause anaemia, aplastic anaemia, pancytopenia, leukopenia, neutropenia, and/or thrombocytopenia. Clinical sequelae such as fever, infections and haemorrhage from various sites may be expected. Pre-treatment and periodic haematological studies are essential to the use of methotrexate in chemotherapy as haematopoietic suppression may occur abruptly and on apparent safe dosage, and any profound drop in blood cell count indicates immediate stopping of the drug and appropriate therapy. In patients with malignant disease who have pre-existing bone marrow aplasia, leukopenia, thrombocytopenia or anaemia, methotrexate should be used with caution, if at all (refer to section 4.3). In the treatment of neoplastic diseases, methotrexate should be continued only if the potential benefit outweighs the risk of severe myelosuppression.
Laboratory monitoring
Before beginning methotrexate therapy or reinstituting methotrexate after a rest period, assessment of renal function, liver function and blood elements should be made by history, physical examination and laboratory tests.
In general, the following laboratory tests are recommended as part of essential clinical evaluation and appropriate monitoring of patients chosen for or receiving methotrexate therapy: complete haemogram, haematocrit, urinalysis, renal function tests, liver function tests and chest X-ray. The purpose is to determine any existing organ dysfunction or system impairment. The tests should be performed prior to therapy, at appropriate periods during therapy and after termination of therapy.
Full blood counts should be closely monitored before, during and after treatment. If a clinically significant drop in white-cell or platelet count develops, methotrexate should be withdrawn immediately. Patients should be advised to report all symptoms or signs suggestive of infection.
These laboratory parameters should be performed with reference to local or national clinical guidelines, at regular intervals, with increased frequency in specific circumstances as per clinician's discretion.
Other
Methotrexate is bound in part to serum albumin after absorption, and toxicity may be increased because of displacement by certain drugs such as salicylates, sulphonamides, phenytoin and some antibacterials such as tetracycline, chloramphenicol and para-aminobenzoic acid. These drugs, especially salicylates and sulphonamides, whether antibacterial, hypoglycaemic or diuretic, should not be given concurrently until the significance of these findings is established. See section 4.5
Vitamin preparations containing folic acid or its derivatives may alter response to methotrexate.
Methotrexate should be used with extreme caution in the presence of infection, peptic ulcer, ulcerative colitis, debility, and in extreme youth and old age. If profound leukopenia occurs during therapy, bacterial infection may occur or become a threat. Cessation of the drug and appropriate antibiotic therapy is usually indicated. In severe bone marrow depression, blood or platelet transfusions may be necessary.
Excipient information
Methotrexate 50 mg/2 ml and 250 mg/10 ml contain less than 1 mmol sodium (23 mg) per vial, that is to say essentially 'sodium free'.
Methotrexate 500 mg/20 ml contains 41.1 mg sodium per vial, equivalent to 2.06% of the WHO recommended maximum daily intake of 2 g sodium for an adult.
Methotrexate 1 g/40 ml contains 82.2 mg sodium per vial, equivalent to 4.11% of the WHO recommended maximum daily intake of 2 g sodium for an adult.