Leucovorin is a specific antidote for methotrexate and, following accidental overdosage, should be administered within one hour at a dosage equal to, or greater than, the methotrexate dose. It may be administered by i.v. bolus or infusion. Further doses may be required. The patient should be observed carefully and blood transfusions, renal dialysis and reverse barrier nursing may be necessary.
In cases of massive overdose, hydration and urinary alkalisation may be necessary to prevent precipitation of methotrexate and/or its metabolites in the renal tubules. Neither haemodialysis nor peritoneal dialysis has been shown to improve methotrexate elimination. Effective clearance of methotrexate has been reported with acute, intermittent haemodialysis using a high flux dialyser.
Cases of overdose, sometimes fatal, due to erroneous daily intake instead of weekly intake of oral methotrexate have been reported. In these cases, symptoms that have been commonly reported are haematological and gastrointestinal reactions.
60 months.
Patients with a known allergic hypersensitivity to methotrexate or any of the excipients should not receive methotrexate.
None stated.
Maize starch
Lactose
Pregelatinised starch
Polysorbate 80
Microcrystalline cellulose
Magnesium stearate
Purified water
Tablet.
'Capsule-shaped', uncoated, convex deep yellow tablets marked with 'M10' and scored on the same side.
In general, the incidence and severity of side effects are considered to be dose-related. Adverse reactions for the various systems are as follows:
Skin:
Stevens-Johnson Syndrome, epidermal necrolysis, erythematous rashes, pruritus, urticaria, 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 has been reported. The recall phenomenon has been reported in both radiation and solar damaged skin.
Haematopoietic:
Bone marrow depression is most frequently manifested by leucopenia, thrombocytopenia (which are usually reversible) and anaemia, or any combination may occur. Infection or hypogammaglobulinaemia has been reported.
Alimentary System:
Mucositis (most frequently stomatitis although gingivitis, pharyngitis and even enteritis, intestinal ulceration and bleeding) may occur. In rare cases the effect of Methotrexate on the intestinal mucosa has led to malabsorption or toxic megacolon. Nausea, anorexia and vomiting and/or diarrhoea may also occur.
Hepatic:
Hepatic toxicity resulting in significant elevations of liver enzymes, acute liver atrophy, necrosis, fatty metamorphosis, periportal fibrosis or cirrhosis or death may occur, usually following chronic administration.
Urogenital System:
Renal failure and uraemia may follow methotrexate administration, particularly after high doses or prolonged administration. Vaginitis, vaginal ulcers, cystitis, haematuria and nephropathy have also been reported.).
Pulmonary System:
Infrequently an 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.
In the treatment of rheumatoid arthritis, methotrexate induced lung disease is a potentially serious adverse drug reaction which may occur acutely at any time during therapy. It is not always fully reversible. Pulmonary symptoms (especially a dry, non productive cough) may require interruption of treatment and careful investigation.
Central Nervous System:
Headaches, drowsiness, ataxia and blurred vision have occurred following low doses of methotrexate, transient subtle cognitive dysfunction, mood alteration, or unusual cranial sensations have been reported occasionally. Aphasia, paresis, hemiparesis, and convulsions have also occurred following administration of higher doses.
There have been reports of leucoencephalopathy following intravenous methotrexate in high doses, or low doses following cranial-spinal radiation.
Other reports include eye irritation, malaise, undue fatigue, vasculitis, sepsis, arthralgia/myalgia, chills and fever, dizziness, loss of libido/impotence and decreased resistance to infection. Also opportunistic infections such as herpes zoster. Osteoporosis, abnormal (usually "megaloblastic") red cell morphology, precipitation of diabetes, other metabolic changes, and sudden death in relation to or attributed to the use of methotrexate.
Although very rare, anaphylactic reactions to methotrexate have been reported.
No further preclinical safety data are available.
Methotrexate is a folic acid antagonist and is classified as an antimetabolite cytotoxic agent.
Methotrexate has been used to produce regression in a wide range of neoplastic conditions including acute leukaemias, non-Hodgkin's lymphoma, soft-tissue and osteogenic sarcomas, and solid tumours particularly breast, lung, head and neck, bladder, cervical, ovarian, and testicular carcinoma.
Methotrexate has also been used in the treatment of severe, uncontrolled psoriasis which is not responsive to other therapy.
Methotrexate is a folic acid antagonist and its major site of action is the enzyme dihydrofolate reductase. Its main effect is inhibition of DNA synthesis but it also acts directly both on RNA and protein synthesis. Methotrexate is a phase specific substance, the main effect being directed during the S-phase of cell division.
The inhibition of dihydrofolate reductase can be circumvented by the use of leucovorin (folinic acid; citrovorum factor) and protection of normal tissues can be carried out by properly timed administration of leucovorin calcium.
When given in low doses, methotrexate is rapidly absorbed from the GI tract giving plasma concentrations equivalent to those achieved after i.v. administration. Higher doses are less well absorbed. About 50% has been shown to be protein bound. Biphasic and triphasic plasma clearance has been shown. The majority of the dose is excreted within 24 hours in the urine mainly as unchanged drug.
01/2018
Maxtrex Tablets 10.0 mg
Pfizer Limited
Ramsgate Road
Sandwich
Kent
CT13 9NJ
United Kingdom
None stated.
White high density polyethylene container with high density polyethylene screw closure containing 100 tablets.
PL 00057/1009
Each tablet contains methotrexate Ph. Eur. 10.0 mg.
For excipients, see 6.1.
- The prescriber may specify the day of intake on the prescription.
- Patients should be aware of importance of adhering to the once weekly intakes.
Methotrexate should be used with extreme caution in patients with haematological depression, renal impairment, diarrhoea, ulcerative disorders of the GI tract and psychiatric disorders. Hepatic toxicity has been observed, usually associated with chronic hepatic disease. The administration of low doses of methotrexate for prolonged periods may give rise, in particular, to hepatic toxicity. Liver function should be closely monitored. If hepatic function abnormalities develop, methotrexate dosing should be suspended for at least two weeks. It is only appropriate to restart methotrexate provided the abnormalities return to normal and the re-exposure is deemed appropriate.
Particular care and possible cessation of treatment are indicated if stomatitis or GI toxicity occurs as haemorrhagic enteritis and intestinal perforation may result.
Reversible eosinophilic pulmonary reactions and treatment-resistant, interstitial fibrosis may occur, particularly after long-term treatment.
Renal lesions may develop if the urinary flow is impeded and urinary pH is low, especially if large doses have been administered.
Renal function should be closely monitored before, during and after treatment. Reduce dose of methotrexate in patients with renal impairment. High doses may cause the precipitation of methotrexate or its metabolites in the renal tubules. A high fluid throughput and alkalinisation of the urine to pH 6.5 - 7 by oral or intravenous administration of sodium bicarbonate (5x625mg tablets every three hours) is recommended as a preventative measure.
Haematopoietic suppression caused by methotrexate may occur abruptly and with apparently safe dosages. 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 therapy should be withdrawn immediately and appropriate supportive therapy given. Patients should be advised to report all symptoms or signs suggestive of infection.
Malignant lymphomas may occur in patients receiving low dose methotrexate, in which case therapy must be discontinued. Failure of the lymphoma to show signs of spontaneous regression requires the initiation of cytotoxic therapy.
Methotrexate has been shown to be teratogenic; it has been reported to cause foetal death and/or congenital abnormalities. Therefore, it is not recommended in women of childbearing potential unless the benefits can be expected to outweigh the considered risks. If this drug is used during pregnancy for antineoplastic indications, or if the patient becomes pregnant while taking this drug, the patient should be appraised of the potential hazard to the foetus.
Following administration to a man or woman conception should be avoided by using an effective contraceptive method for at least 3 months after using Maxtrex Tablets 10mg.
Methotrexate has some immunosuppressive activity and therefore the immunological response to concurrent vaccination may be decreased. In addition, concomitant use of a live vaccine could cause severe antigenic reaction.
Methotrexate should only be used by clinicians that are familiar with the various characteristics of the drug and its mode of action. Before beginning methotrexate therapy or reinstituting methotrexate after a rest period, a chest x-ray, assessment of renal function, liver function and blood elements should be made by history, physical examination and laboratory tests. This will include a routine examination of lymph nodes and patients should report any unusual swelling to the doctor.
Patients receiving low-dose methotrexate should:
- Have a full blood count and renal and liver function tests before starting treatment. These should be repeated weekly until therapy is stabilised, thereafter patients should be monitored every 2-3 months throughout treatment.
- Patients should report all symptoms and signs suggestive of infection, especially sore throat.
If acute methotrexate toxicity occurs, patients may require treatment with folinic acid.
The disappearance of methotrexate from plasma should be monitored, if possible. This is recommended in particular when high, or very high doses are administered in order to permit calculation of an adequate dose of leucovorin (folinic acid) rescue.
Patients with pleural effusions and ascites should be drained prior to initiation of methotrexate therapy. A chest x-ray is recommended prior to initiation of methotrexate therapy or treatment should be withdrawn.
Methotrexate given concomitantly with radiotherapy may increase the risk of soft tissue necrosis and osteonecrosis.
Acute or chronic pneumonitis, often associated with blood eosinophilia, may occur and deaths have been reported. Symptoms typically include dyspnoea, cough (especially a dry productive cough) 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.
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.
Lung manifestations of RA and other connective tissue disorders are recognised to occur. In patients with RA, the physician should be specifically alerted to the potential for methotrexate induced adverse effects on the pulmonary system.
None known.
Method of Administration: Oral.
Dosage for cancer treatment:
A test dose of 5 - 10 mg parenterally is recommended, one week prior to therapy to detect idiosyncratic adverse events. Single doses, not exceeding 30 mg/m2, on not more than 5 consecutive days. A rest period of at least two weeks is recommended between treatments, in order to allow the bone marrow to return to normal.
Doses in excess of 100 mg are usually given parenterally, when the injectable preparation should be used. Doses in excess of 70 mg/m2 should not be administered without leucovorin rescue (folinic acid rescue) or assay of serum methotrexate levels 24 - 48 hours after dosing.
If methotrexate is administered in combination chemotherapy regimens, the dosage should be reduced, taking into consideration any overlapping toxicity of the other drug components.
Dosage for psoriasis:
For the treatment of severe psoriasis 10 - 25 mg orally, once a week is recommended. Dosage should be adjusted according to the patient's response and the haematological toxicity. The prescriber may specify the day of intake on the prescription.
None.
17 July 2002
