Abitrexate

/ Salomon, Levin & Elstein Ltd

The dose must be adjusted carefully depending on the body surface area if methotrexate is used for the treatment of tumour diseases. Fatal cases of intoxication have been reported after administration of incorrect calculated doses. Health care professionals and patients should be fully informed about toxic effects. Treatment should be initiated by or occur in consultation with a doctor with significant experience in cytostatic treatment. Methotrexate may be administered by intramuscular, intravenous (bolus injection or infusion), intrathecal, intraventricular or intra-arterial. For intrathecal administration, Methotrexate is administered as a 1 mg/ml solution, using an appropriate sterile preservative-free medium such as Sodium Chloride Injection. Dosages are based on the patient’s bodyweight or surface area, except in the case of intrathecal or intraventricular administration, when a maximum dose of 15 mg is recommended. Dosage should be reduced in cases of hematological deficiency and hepatic or renal impairment. When administered by infusion, Methotrexate should only be diluted with normal saline. Larger doses (more than 100 mg) are usually administered by intravenous infusion over periods not exceeding 24 hours. Part of the dose may be administered as an initial rapid intravenous injection Methotrexate has been used with beneficial effects in a wide variety of neoplastic diseases, alone and in combination with other cytotoxic agents, hormones, immunotherapy, radiotherapy or surgery. Therefore, dosage schedules vary considerably depending on the clinical use, particularly when intermittent high-dose regimens are followed by the administration of calcium leucovorin in order to rescue normal cells from toxic effects. Dosage regimens for calcium leucovorin rescue are discussed at the end of this section. The following are some examples of the dosages of Methotrexate that have been used for particular indications:
Choriocarcinoma and Other Trophoblastic Tumors: By the intramuscular route, in doses of 15-30 mg daily for a 5-day course. Such courses are usually repeated 3-5 times as required, with rest periods of 1 or more weeks between courses, until any toxic symptoms subside. The effectiveness of therapy is ordinarily evaluated by 24-hour quantitative analysis of urinary human chorionic gonadotrophin (HCG), which should return to normal or less than 50 IU/24 hours, usually after the 3rd or 4th course of treatment, and also usually followed by a complete resolution of measurable lesions in 4-6 weeks. After the normalization of HCG, 1 or 2 courses of Methotrexate are usually recommended. Before each course of the drug, careful clinical assessment is essential. Higher doses of up to 60 mg i.m. every 48 hours may be administered for 4 doses, followed by calcium leucovorin rescue. This course is repeated at 7-day intervals until levels of urinary HCG return to normal. Not less than 4 courses of treatment are usually necessary. Patients with complications, such as extensive metastases, may be treated with Methotrexate in cyclic combination with other cytotoxic drugs.
Chorioadenoma Destruens and Hydatidiform Mole: Since hydatidiform mole may be followed by choriocarcinoma, prophylactic chemotherapy with Methotrexate has been recommended. Chorioadenoma destruens is considered to be an invasive form of hydatidiform mole. Methotrexate is administered in these disease states in doses similar to those recommended for choriocarcinoma.
Lymphoblastic Leukemia: Daily administration of Methotrexate 3.3 mg/m², in combination with prednisone 60 mg/m², is used as induction therapy in acute lymphatic (lymphoblastic) leukemia in children and young adolescents. Methotrexate alone, or in combination with other agents, appears to be a drug of choice for securing maintenance of drug-induced remissions. When remission is achieved and supportive care has produced general clinical improvement, maintenance therapy is initiated with intramuscular methotrexate 30 mg/m², twice weekly. It has also been administered intravenously in doses of 2.5 mg/kg body weight, every 14 days. If relapse does occur, reinduction of remission can again usually be obtained by repeating the initial induction regimen.
Meningeal Leukemia: Administer 12 mg/m² intrathecally, or an empirical dose of 15 mg. Dilute methotrexate to a concentration of 1 mg/ml using a sterile, preservative-free medium such as 0.9% Sodium Chloride Injection. Administer at intervals of 2-5 days, and repeat until the CSF cell count returns to normal. Then administer one additional dose. Administration at intervals of less than 1 week may result in increased subacute toxicity. For prophylaxis against meningeal leukemia, the dosage is the same as for treatment, except for the intervals of administration. The CSF volume is dependent on age, and not on body surface area (BSA). The CSF is at 40% of the adult volume at birth and reaches the adult volume in several years. Intrathecal methotrexate 12 mg/m² (maximum 15 mg) has resulted in low CSF methotrexate concentrations and reduced efficacy in children, and high concentrations and neurotoxicity in adults. The following dosage regimen is based on age instead of BSA, and appears to result in more consistent CSF methotrexate concentrations and less neurotoxicity. See prescribing information for Intrathecal Methotrexate Dosage According to Age. Because the CSF volume and turnover may decrease with age, a dose reduction may be indicated in elderly patients.
Lymphomas: In stage III, give methotrexate concomitantly with other antitumor agents. Treatment in all stages generally consists of several courses with 7-10 day rest periods between each course. Lymphosarcomas in stage III may respond to combined drug therapy with methotrexate 0.625-2.5 mg/kg body weight/day.
Mycosis Fungoides: Although the usual treatment is by orally-administered methotrexate, methotrexate has also been given intramuscularly in doses of 50 mg once a week, or 25 mg twice weekly.
Breast Cancer: Methotrexate in intravenous doses of 10-60 mg/m² is commonly included in cyclical combination regimens with other cytotoxic drugs in the treatment of advanced breast cancer. Similar regimens have also been used as adjuvant therapy in early cases following mastectomy and/or radiotherapy.
Osteosarcoma: Effective therapy requires several cytotoxic chemotherapeutic agents. In addition to high-dose methotrexate with leucovorin rescue, these agents may include doxorubicin, cisplatin and the combination of bleomycin, cyclophosphamide and dactinomycin (BCD) in the doses and schedule shown in the Table below. The starting dose for high-dose methotrexate treatment is 12g/m². If this is insufficient to produce a peak serum concentration of 1,000 micromole per L (0.001 mol/l) at the end of the methotrexate infusion, the dose may be increased to 15g/m² in subsequent treatments. If the patient is vomiting or unable to tolerate leucovorin orally, administer leucovorin I.V. or I.M. at the same dose and schedule. See prescribing information for Chemotherapy Regimens for Osteosarcoma.
Bronchogenic Carcinoma: Intravenous infusions of 20-100 mg/m² of Methotrexate have been included in cyclical combination regimens for the treatment of advanced tumors. Higher doses of Methotrexate with calcium leucovorin rescue may also be employed as sole treatment.
Head and Neck Cancer: Intravenous infusions of 240-1,080 mg/m² of Methotrexate with calcium leucovorin rescue may be used both as preoperative adjuvant therapy and in the treatment of advanced tumors. Intra-arterial infusions of Methotrexate are indicated for certain head and neck cancers, although this route of administration is not used extensively.
Bladder Carcinoma: Intravenous injections or infusions of Methotrexate in doses up to 100 mg every 1-2 weeks may be used in the treatment of bladder carcinoma. Diuretics and hydration are employed in an attempt to reduce the excessive drug toxicity that may occur in patients with renal impairment.
Psoriasis: Patients should be fully informed of the potential risks involved, and should be under the constant supervision of the treating physician. The usual dose in cases of severe, uncontrolled psoriasis unresponsive to conventional therapy is 10-25 mg, administered intramuscularly or intravenously once a week and adjusted according to the patient’s response.
Rheumatoid Arthritis: Initially, 10 mg/week may be administered either intramuscularly or intravenously. The dosage may be increased to 25 mg/week. Duration of treatment varied in clinical studies from 6 weeks to 13 weeks. An intramuscular dosage of 15 mg/week has been administered over a period of 6 months. An initial dosage of 10 mg/week IV, increased to a maximum of 50 mg/week IV has been administered over a period of 2 months. Particular attention should be given to the appearance of liver toxicity by performing liver function tests before initiating Methotrexate treatment, and repeating the tests at 2-4 month intervals during therapy. Therapy should not be instituted, or should be discontinued, if any abnormality of liver function tests or of a liver biopsy is present or develops during therapy. Such abnormalities should return to normal within 2 weeks, after which, treatment may be recommended at the discretion of the physician. The use of Methotrexate may permit the return to conventional topical therapy which should be encouraged.
Calcium Leucovorin Rescue: When administering high doses of methotrexate, the following guidelines for methotrexate therapy with leucovorin rescue should be closely observed
Methotrexate administration should be delayed until recovery if:
the WBC count is less than 1500mm³, the neutrophil count is less than 500mm³, the platelet count is less than 75,000mm³ ,the serum bilirubin level is more than 1.2 mg/dl, the ALT level is more than 450 U, mucositis is present, until there is evidence of healing, persistent pleural effusion and ascite are present; drain dry prior to infusion.
Adequate renal function must be documented. Serum creatinine must be normal and creatinine clearance must be more than 60 ml/min. before the initiating of therapy. Serum creatinine must be measured prior to each subsequent course of therapy. If serum creatinine has increased by 50% or more in comparison to a prior value, the creatinine clearance must be measured and documented to be more than 60 ml/min. (even if the serum creatinine is still within the normal range).
Patients must be well hydrated, and must be treated with sodium bicarbonate for urinary alkalinization. Administer 1,000 ml/m² of intravenous fluid over 6 hours prior to initiating of the methotrexate infusion. Continue hydration at 125 ml/m²/hour (3L/m²/day) during methotrexate infusion, and for 2 days after the infusion has been completed.
Alkalinize urine to maintain a pH above 7.0 during methotrexate infusion and leucovorin calcium therapy by giving sodium bicarbonate orally or by incorporation into a separate i.v. solution. Repeat serum creatinine and serum methotrexate 24 hours after starting methotrexate, and at least once daily until the methotrexate level is below 5×10-8 mol/l (0.05 micromolar).
Patients who experience delayed/early methotrexate elimination are likely to develop irreversible oliguric renal failure. In addition to appropriate leucovorin therapy, these patients require continuing hydration and urinary alkalinization and close monitoring of fluid and electrolyte status, until the serum methotrexate level has fallen to less than 0.05 micromolar and the renal failure has resolved.
Some patients will have abnormalities in methotrexate elimination or abnormalities in renal function following methotrexate administration which are significant, but less severe, than those described in the Table. These abnormalities may, or may not be, associated with significant clinical toxicity. If significant clinical toxicity is observed, leucovorin rescue should be extended for an additional 24 hours (total of 14 doses over 84 hours) in subsequent courses of therapy. When laboratory abnormalities or clinical toxicities are observed, the possibility that the patient is taking other medications which interact with methotrexate should be considered.
See prescribing information for full details.
Older People: Dose reduction should be considered in elderly patient due to reduced liver and kidney functin as well as reserves which occur with increased age.
Hepatic Function Impairment: If the bilirubin is between 3-5, or AST more than 180, dosage should be reduced by 25%. If bilirubin is more than 5, omit the dose. Methotrexate should be administered with great caution, if at all, to patients with significant current or previous liver disease, especially when caused by alcohol. Methotrexate is contraindicated if bilirubin values are >5 mg/dl (85.5 μmol/L).         

Antineoplastic chemotherapy: Treatment of gestational choriocarcinoma, chorioadenoma destruents and hydatidiform mole. Palliation of acute lymphocytic leukemia. Treatment and prophylaxis of meningeal leukemia. Greatest effect has been observed in palliation of acute lymphoblastic (stem cell) leukemias in children. In combination with other anticancer agents, may be used for the induction of remission, but is most commonly used in maintenance of induced remissions. May be used alone or in combination with other antineoplastics in the management of breast cancer, epidermoid cancers of the head and neck, lung cancer (particularly squamous cell and small cell types), bladder cancer and osteogenic cancer. Effective in the treatment of the advanced stages (III and IV Peter’s Staging System) of lymphosarcoma, particularly in children, and in advanced cases of mycosis fungoides.
Psoriasis: because of the high risk attending its use, treatment is indicated only in the symptomatic control of severe recalcitrant, disabling psoriasis which is not adequately responsive to other forms of therapy, and only when the diagnosis has been established, as by biopsy and/or after dermatological consultation.
Rheumatoid arthritis: Can be used in the treatment of selected adults with severe rheumatoid arthritis, only when the diagnosis has been well estabished according to rheumatological standards, with inadequate response to other forms of antirheumatic therapy, including full dose NSAIDs and usually a trial of at least one or more disease-modifying antirheumatic drugs.

Methotrexate should not be used in pregnancy, and in patients in a poor state of nutrition. Methotrexate is furthermore contraindicated in patients with serious renal (Creatinine clearance less than 20 ml/min) severe liver disorders, bone marrow hypoplasia, leucopenia, thrombocytopenia, anaemia, alcohol abuse, methotrexate hypersensitivity and lung toxicity due to methotrexate. During methotrexate therapy no breastfeeding should be given. Serious, acute or chronic infections such as tuberculosis and HIV. Ulcers of the oral cavity and known active gastrointestinal ulcer disease. Concurrent vaccination with live vaccines.

The cytostatic drug methotrexate may only be used under strict supervision of a physician who is experienced in oncology. Treatment should take place in a hospital experienced in cancer chemotherapy. Fatal toxicity in association with intravenous and intrathecal administration due to dose miscalculation has been reported. Particular caution should be exercised when calculating the dose. Because of the risk of severe toxic reactions (which can be fatal), methotrexate must only be used in life-threatening neoplastic diseases. Deaths have been reported during treatment of malignancies with methotrexate. The doctor should inform the patient of the risks of treatment and the patient should be monitored constantly by the doctor. Methotrexate has reportedly caused fetal death and/or congenital malformations. Treatment of neoplastic diseases is not recommended in women of childbearing potential unless there are clear medical indications that the benefits of treatment can be expected to outweigh the conceivable risks. Methotrexate affects spermatogenesis and oogenesis during the period in which it is administered, which can result in reduced fertility. These effects may be reversible on discontinuing treatment.
Tumor lysis syndrome: Like other cytotoxic agents, methotrexate can induce tumour lysis syndrome in patients with rapidly growing tumours. Appropriate supportive treatment and pharmacological measures can prevent or alleviate such complications.
Methotrexate and NSAIDs: Unexpected severe (including fatal) myelosuppression, aplastic anaemia and gastrointestinal toxicity have been reported in connection with concomitant treatment with methotrexate (usually at a high dose) and non-steroidal anti-inflammatory agents (NSAIDs). Concomitant methotrexate treatment and radiotherapy can increase the risk of soft tissue necrosis and osteonecrosis. Intrathecal and intravenous administration of methotrexate can result in acute encephalitis and acute encephalopathy, possibly with a fatal outcome. Patients with periventricular CNS lymphoma who are given methotrexate intrathecally have reportedly developed cerebral herniation.
Methotrexate and pleural effusion/ascites: Methotrexate is eliminated slowly from collections of fluid (e.g. pleural effusion, ascites). This results in a prolonged terminal half-life and unexpected toxicity. In patients with significant collections of fluid, drainage of the fluid before treatment is started and monitoring of plasma methotrexate levels are recommended. If stomatitis, diarrhoea, haematemesis or black stool occurs, therapy with methotrexate should be discontinued due to the danger of haemorrhagic enteritis or death from intestinal perforation or dehydration. Conditions in which there is folic acid deficiency can increase the risk of methotrexate toxicity. In association with intrathecal administration or in high dose treatment, methotrexate must not be mixed with solutions which contain preservatives. Solutions of methotrexate which contain the preservative benzyl alcohol are not recommended for use in infants. Gasping syndrome with fatal outcome has been reported in infants following intravenous treatment with solutions containing the preservative benzyl alcohol. Symptoms include rapid onset of respiratory problems, hypotension, bradycardia and cardiovascular collapse.
For full details see prescribing information.

Ulcerative stomatitis, leukopenia, nausea and abdominal distress, malaise, fatigue, chills, fever, dizziness and decreased resistance to infection, rashes, pruritus, urticaria, photosensitivity, depigmentation, alopecia, ecchymosis, telangiectasia, acne and furunculosis, bone marrow depression, leukopenia, thrombocytopenia, anemia, hypogammaglobulinemia, hemorrhage and septicemia, anorexia, vomiting, diarrhea, hematemesis, melena, gastrointestinal ulceration and bleeding, enteritis, hepatic toxicity, renal failure, azotemia, cystitis, hematuria, severe nephropathy, defective oogenesis or spermatogenesis, menstrual dysfunction, infertility, abortion and fetal defects, interstitial pneumonitis and chronic interstitial obstructive pulmonary disease, CNS toxicity.
For full details see prescribing information.

Non steroidal anti-inflammatory drugs (NSAIDS) should not be administered prior to or simultaneously with high dose methotrexate treatment (>10 mg methotrexate per week). Increased serum levels of methotrexate have been reported at simultaneous administration of some NSAIDS with high dose methotrexate resulting in death by serious haematologic or gastrointestinal toxicity. NSAIDS, salicylates and other weak organic acids, like probenecid, can lower tubularly secretion of methotrexate resulting in increased toxicity. Use of methotrexate with these drugs should be made carefully under strict supervision. The potential toxicity of methotrexate is increased in particular at simultaneous use of NSAIDS when also diuretics are used. In rheumatology, a combination therapy of low-dose methotrexate and a NSAID is commonly used. Methotrexate bound to serum proteins may be displaced by salicylates, NSAID’s, sulphonamides, phenytoin, tetracyclines, chloramphenicol, p-amino-benzoic acid, doxorubicin, bleomycin, cyclophosphamide, aminoglycosides, allopurinol, vincristine, hydrocortisone, prednisone, asparaginase and cytosine arabinoside, hereby increasing the fraction of free methotrexate in plasma. Care should be taken in combining high dose methotrexate with potentially nephrotoxic therapy (e.g. cisplatin). Oral antibiotics (including tetracyclines, chloramphenicol and non-absorbable broad-spectrum antibiotics) may influence the intestinal flora and inhibit methotrexate (re)absorption. In isolated cases, trimethoprim/sulfamethoxazole has reportedly increased myelosuppression in patients treated with methotrexate, probably due to reduced tubular secretion and/or an additive antifolate effect Interaction with therapeutic radiation may occur. In combination with other cytostatic drugs pharmacodynamic interactions may occur; resulting in increased therapeutic activity and increased toxicity. No vaccination with live virus vaccines should be performed in patients receiving methotrexate. Partial or total protection can be obtained through inactivated vaccines. Vitamin preparations containing folic acid or folic acid derivatives may decrease the effect of systemically administered methotrexate. Preliminary human and animal studies have shown that after intravenous administration of calcium folinate a small amount penetrates into the cerebrospinal fluid, predominantly as 5-methyltetrahydrofolate, and this amount is a factor 1 to 3 lower than the normal methotrexate concentration after intrathecal administration. Nevertheless high doses of calcium folinate may lower the effectivity of intrathecally administered methotrexate. Folate deficiencies may increase methotrexate toxicity. In some cases a potentiation of the bone marrow suppression in patients treated with methotrexate by trimethoprim/sulphamethoxazole was reported, probably by additional folic acid antagonism. The combined use of methotrexate and sulphonamides is therefore strongly advised against. Ciprofloxacin: Excretion of methotrexate possibly reduced (increased risk of toxicity).
Leflunomide: Methotrexate in combination with leflunomide can increase the risk of pancytopenia.
Probenecid: Renal tubular transport is diminished by probenecid, and its use together with methotrexate must be avoided.
Penicillins: Penicillins can reduce renal clearance of methotrexate. Haematological and gastrointestinal toxicity have been observed in combination with high and low dose methotrexate.
Chemotherapeutic products: An increase in renal toxicity can be observed when high doses of methotrexate are given in combination with potentially nephrotoxic chemotherapeutic agents (e.g. cisplatin).
Cytarabine: Concomitant therapy with cytarabine and methotrexate can increase the risk of severe neurological side effects ranging from headache to paralysis, coma and stroke-like episodes.
Hepatotoxic products: The risk of increased hepatotoxicity when methotrexate is administered concurrently with other heptatotoxic products has not been studied. Hepatotoxicity has however been reported in such cases. Patients receiving concomitant treatment with drugs with a known hepatotoxic effect (e.g. leflunomide, azathioprine, sulfasalazine, retinoids) must be carefully monitored for signs of any increase in hepatotoxicity.
Theophylline: Methotrexate can reduce clearance of theophylline. Theophylline levels must therefore be monitored during concomitant treatment with methotrexate.
Mercaptopurine: Methotrexate increases plasma content of mercaptopurine. The combination of methotrexate and mercaptopurine can therefore require dose adjustment.
Drugs with high plasma protein binding: Methotrexate is partially bound to serum albumin. Other highly bound drugs such as salicylates, phenylbutazone, phenytoin and sulfonamides can increase the toxicity of methotrexate by means of displacement.
Furosemide: Concomitant administration of furosemide and methotrexate can result in increased levels of methotrexate due to competitive inhibition of tubular secretion.
For full details see prescribing information.

Pregnancy: Methotrexate can cause foetal death, embryotoxicity, abortion or teratogenic effects when administered to pregnant women. During pregnancy, especially in the first trimester, cytotoxic drugs must only be given when strictly indicated, weighing the needs of the mother against the risks to the foetus. Treatment with methotrexate during the first trimester has resulted in a high risk of malformations (in particular cranial malformation and malformation of the extremities).
Lactation: Methotrexate passes into breast milk in quantities such that there is a risk to the child even at therapeutic doses. Breast feeding must therefore be discontinued during treatment with methotrexate.
See prescribing information for full details.

Experience of overdose with the product has in general been associated with oral and intrathecal treatment, although overdose in association with intravenous and intramuscular administration has also been reported. Reports of oral overdose have often been due to accidental daily instead of weekly ingestion. Commonly reported symptoms following oral overdose include the symptoms and signs seen at pharmacological doses, in particular haematological and gastrointestinal reactions such as leukopenia, thrombocytopenia, anaemia, pancytopenia, neutropenia, myelosuppression, mucositis, stomatitis, oral ulceration, nausea, vomiting, gastrointestinal ulceration, gastrointestinal bleeding. In certain cases no symptoms were reported. There are reports of deaths associated with overdose. In these cases there were also reports of conditions involving sepsis or septic shock, renal failure and aplastic anaemia. The most common symptoms of intrathecal overdose are CNS symptoms including headache, nausea and vomiting, seizures or convulsions and acute toxic encephalopathy. In certain cases, no symptoms were reported. There have been reports of deaths following intrathecal overdose. In these cases there were also reports of cerebellar herniation accompanying elevated intracranial pressure and toxic encephalopathy.
Recommended treatment Antidote therapy: Folinic acid should be given parenterally at a dose at least the size of the methotrexate dose and should wherever possible be administered within an hour. Folinic acid is indicated to minimise toxicity and counter the effect of methotrexate overdose. Folinic acid treatment should be initiated as soon as possible. The longer the interval between the administration of methotrexate and the initiation of folinic acid, the less the effect of folinic acid in suppressing the toxic effect. Monitoring of serum methotrexate concentrations is necessary to be able to determine the optimum dose of folinic acid and the length of the treatment. In the event of a major overdose, hydration and alkalinisation of the urine may be required to prevent precipitation of methotrexate and/or its metabolites in the renal tubules. Neither standard haemodialysis nor peritoneal dialysis have been shown to increase the elimination of methotrexate. Acute intermittent haemodialysis with the use of highly permeable dialyser may be attempted for methotrexate intoxication. Intrathecal overdose may require intensive systemic supportive measures such as systemic administration of high doses of folinic acid, alkaline diuresis, acute CSF drainage and ventricular lumbar perfusion.

Sodium: Methotrexate solution or injection contains sodium as follows:
Methotrexate Injection 25 mg/ml Solution for Injection: Each ml contains 1.93 mg sodium.
Methotrexate Injection 1g/10 ml (100 mg/ml) Solution for Injection: Sodium content: Each ml contains 10 mg sodium. This should be taken into consideration by patients on a controlled sodium diet.
Incompatibilities: Methotrexate should not be mixed in the infusion bottle with other drugs.
Storage: Store in a dry place at room temperature (15-25°C) in a well closed packaging. Protect from light.
Do not use this medicine if the solution is not clear. Abitrexate solution can be further diluted with 0.9% Sodium Chloride Injection or 5% Dextrose Injection. Diluted solution stored between 15-250C and protected from light has a chemical and physical in-use stability of 24 hours. From a microbiological point of view, unless the method of dilution precludes the risk of microbial contamination, the product should be used immediately. If not used immediately, in-use storage times and conditions are the responsibility of the user.
Special precautions for disposal and other handling: Every form of contact with the fluid must be avoided. During preparation a strictly aseptic working technique should be used; protective measures should include the use of gloves, mask, safety goggles and protective clothing. Use of vertical laminar airflow (LAF) hood is recommended. If the solution is spilled, rinse with plenty of water. Gloves should be worn during administration. Waste-disposal procedures should take into account the cytotoxic nature of this substance.