Folic acid antagonists (antimetabolites, cytotoxics).

Methotrexate - neoplastic conditions

Each tablet contains methotrexate Ph. Eur. 2.5 mg.

Round, uncoated, convex deep yellow tablets marked with 'M2.5' on one side.

Methotrexate is a folic acid antagonist and is classified as an antimetabolite cytotoxic agent. Methotrexate is used in the treatment of adults with severe, active, classical or definite rheumatoid arthritis who are unresponsive or intolerant to conventional therapy. Methotrexate has also been used in the treatment of severe, uncontrolled psoriasis, which is not responsive to other therapy. 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.

Method of Administration: Oral

Dosage and Administration with reference to Rheumatoid arthritis and Psoriasis

Dosage for Rheumatoid arthritis

Adults:

In adults with severe, active, classical or definite rheumatoid arthritis who are unresponsive or intolerant to conventional therapy 7.5 mg orally once weekly or divided oral doses of 2.5 mg at 12 hour intervals for 3 doses (7.5 mg) as a course once weekly. The schedule may be adjusted gradually to achieve an optimal response but should not exceed a total weekly dose of 20 mg. Once response has been achieved, the schedule should be reduced to the lowest possible effective dose.

Dosage for psoriasis:

For the treatment of severe psoriasis 10 - 25 mg orally, once weekly, is recommended. Dosage should be adjusted according to the patient's response and the haematological toxicity.

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.

Safety and effectiveness in children have not been established, other than in cancer chemotherapy.

Methotrexate should be used with extreme caution in elderly patients, a reduction in dosage should be considered.

Methotrexate is contra-indicated in the presence of severe/significant renal or significant hepatic impairment. Liver disease including fibrosis, cirrhosis, recent or active hepatitis; active infectious disease; and overt or laboratory evidence of immunodeficiency syndrome(s). Serious cases of anaemia, leucopenia or thrombocytopenia. Maxtrex should not be used concomitantly with drugs with antifolate properties (eg co-trimoxazole). Methotrexate is teratogenic and should not be given during pregnancy or to mothers who are breast feeding.

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 2.5mg.

Patients with a known allergic hypersensitivity to methotrexate should not receive methotrexate.

Methotrexate should be used with extreme caution in patients with haematological depression, renal impairment, diarrhoea, and 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 (see Undesirable Effects section). 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 2.5mg.

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 or treatment should be withdrawn.

When to perform a liver biopsy in rheumatoid arthritis patients has not been established either in terms of a cumulative Methotrexate dose or duration of therapy.

Pleuropulmonary manifestation of rheumatoid arthritis has been reported in the literature. In patients with rheumatoid arthritis, the physician should be specifically alerted to the potential for Methotrexate induced adverse effects in the pulmonary system. Patients should be advised to contact their physicians immediately should they develop a cough or dyspnoea.

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) 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 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.

Methotrexate is immunosuppressive and may therefore reduce immunological response to concurrent vaccination. Severe antigenic reactions may occur if a live vaccine is given concurrently.

Methotrexate is extensively protein bound and may displace, or be displaced by, other acidic drugs. The concurrent administration of agents such as p-aminobenzoic acid, chloramphenicol, diphenylhydantoins, acidic anti-inflammatory agents, salicylates, sulphonamides, tetracyclines, thiazide diuretics, probenicid or sulfinpyrazone or oral hypoglycaemics will decrease the methotrexate transport function of renal tubules, thereby reducing excretion and almost certainly increasing methotrexate toxicity. Methotrexate dosage should be monitored if concomitant treatment with NSAID's is commenced, as concomitant use of NSAID's has been associated with fatal methotrexate toxicity. Concomitant administration of folate antagonists such as trimethoprim, cotrimoxazole and nitrous oxide should be avoided. Hepatic and nephrotoxic drugs should be avoided.

Acitretin (a treatment for psoriasis) is metabolised to eretinate. Methotrexate levels may be increased by eretinate and severe hepatitis has been reported following concomitant use.

Vitamin preparations containing folic acid or its derivatives may alter response to Methotrexate.

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. Methotrexate can decrease fertility. This effect appears to be reversible after discontinuation of therapy.

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.

Acute or chronic interstitial pneumonitis, often associated with blood eosinophilia, may occur and deaths have been reported.

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.

Pharmacia & Upjohn

(POM)

03 June 2009