Methotrexate Pfizer Dosage/Direction for Use

Anti-neoplastic chemotherapy: Oral administration in tablet form is often preferred since absorption is rapid and effective serum levels are obtained.
Choriocarcinoma and similar trophoblastic diseases: Methotrexate is administered orally in doses of 15 to 30 mg daily for a 5 day course. Such courses are usually repeated for 3 to 5 times as required, with rest periods of one or more weeks interposed between courses, until any manifesting toxic symptoms subside. The effectiveness of therapy is ordinarily evaluated by 24 hour quantitative analysis of urinary chorionic gonadotropin hormone (CGH), which should return to normal or less than 50 IU/24 hr, usually after the 3^rd or 4^th course and usually be followed by a complete resolution of measurable lesions in 4 to 6 weeks. One to two courses of Methotrexate after normalization of CGH is usually recommended. Before each course of the drug, careful clinical assessment is essential. Cyclic combination therapy of Methotrexate with other antitumor drugs has been reported as being useful.
Since hydatidiform mole may precede or 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.
Leukemia: acute lymphatic (lymphoblastic) leukemia in children and young adolescents is the most responsive to present day chemotherapy. In young adults and older patients, clinical remission is more difficult to obtain and early relapse is more common. In chronic lymphatic leukemia, the prognosis for adequate response is less encouraging.
Methotrexate alone or in combination with steroids was used initially for induction of remission of lymphoblastic leukemias. More recently corticosteroid therapy in combination with other antileukemic drugs or in cyclic combinations with Methotrexate included appear to produce rapid and effective remissions. When used for induction, Methotrexate alone or in combination with other agents appears to be the 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, as follows: Methotrexate is administered 2 times weekly by mouth. If and when relapse does occur, reinduction of remission can again usually be obtained by repeating the initial induction regimen. Various experts have recently introduced a variety of dosage schedules for both induction and maintenance of remission with various combinations of alkylating and antifolic agents. Multiple drug therapy with several agents, including Methotrexate given concomitantly is gaining increasing support in both the acute and chronic forms of leukemia. The physician should familiarize himself with the new advances in antileukemic therapy.
Acute granulocytic leukemia is rare in children but common in adults. This form of leukemia responds poorly to chemotherapy and remissions are short with relapses common, and resistance to therapy develops rapidly.
Meningeal leukemia: Patients with leukemia are subject to leukemic invasion of the central nervous system. This may manifest characteristic signs or symptoms or may remain silent and be diagnosed only by examination of the cerebrospinal fluid which contains leukemic cells in such cases. Therefore, the CSF should be examined in all leukemic patients.
For the treatment of meningeal leukemia, Methotrexate is given at intervals of 2 to 5 days. Methotrexate is administered until the cell count of the cerebrospinal fluid returns to normal. At this point one additional dose is advisable.
For prophylaxis against meningeal leukemia, the dosage is the same as for treatment except for the intervals of administration. On this subject, it is advisable for the physician to consult the medical literature.
Lymphomas: In Burkitt's Tumor, Stages I-II, Methotrexate has produced prolonged remissions in some cases. Recommended dosage is 10 to 25 mg per day orally for 4 to 8 days. In stage III, Methotrexate is commonly given concomitantly with other antitumor agents. Treatment in all stages usually consists of several courses of the drug interposed with 7 to 10 day rest periods. Lymphosarcomas in Stage III may respond to combined drug therapy with Methotrexate given in doses of 0.625 mg to 2.5 mg/kg daily. Hodgkin's Disease responds poorly to Methotrexate and to most types of chemotherapy.
Mycosis fungoides (cutaneous T cell lymphoma): Therapy with methotrexate as a single agent appears to produce clinical remission in one half of the cases treated. Dosage is usually 2.5 to 10 mg daily by mouth for weeks or months. Dose levels of drug and adjustment of dose regimen by reduction or cessation of drug are guided by patient response and hematologic monitoring.
Psoriasis Chemotherapy: The patient should be fully informed of the risks involved and should be under constant supervision of the physician.
Assessment of renal function, liver function, and blood elements should be made by history, physical examination, and laboratory tests (such as CBC, urinalysis, serum creatinine, liver function studies, and liver biopsy if indicated) before beginning Methotrexate, periodically during Methotrexate therapy, and before reinstituting Methotrexate therapy after a rest period. Appropriate steps should be taken to avoid conception during and for at least eight weeks following Methotrexate therapy.
There are three commonly used general types of dosage schedules: 1. weekly oral intermittent large doses; 2. divided dose intermittent oral schedule over a 36 hour period; 3. daily oral with a rest period.
All schedules should be continually tailored to the individual patient. Dose schedules cited as follows pertain to an average 70 kg adult. An initial test dose one week prior to initiation of therapy is recommended to detect any idiosyncrasy.
Recommended starting dose schedules: 1. Weekly single oral: 10-25 mg per week until adequate response is achieved. With this dosage schedule, 50 mg per week should ordinarily not be exceeded.
2. Divided oral dose schedule: 2.5 mg at 12 hour intervals for three doses or at 8 hour intervals for four doses each week. With this dosage schedule, 30 mg per week should not be exceeded.
3. Daily oral dose schedule: 2.5 mg daily for five days followed by at least a two day rest period. With this dosage schedule; 6.25 mg per day should not be exceeded.
SPECIAL NOTE: Available data suggest that schedule 3 may carry an increased risk of serious liver pathology.
Dosages in each schedule may be gradually adjusted to achieve optimal clinical response, but not to exceed the maximum stated for each schedule.
Once optimal clinical response has been achieved, each dosage schedule should be reduced to the lowest possible amount of drug and to the longest possible rest period. The use of Methotrexate may permit the return to conventional topical therapy, which should be encouraged.
Rheumatoid arthritis (RA): 1. Single oral doses of 7.5 to 20 mg once weekly.
2. Divided oral doses of 2.5 to 7.5 mg every 12 hours for three doses, repeated weekly.
A total weekly dose 20 mg should not be exceeded. Once optimal clinical response has been achieved, dosing should be reduced to the lowest possible effective dose. The optimal duration of therapy is unknown; limited data from long term studies indicate that the initial clinical improvement is maintained for at least 2 years with continued therapy.
Pediatric use: Safety and effectiveness in pediatric patients have been established only in cancer chemotherapy.
Geriatric use: Fatal toxicities related to inadvertent daily rather than weekly dosing have been reported, particularly in elderly patients. It should be emphasized to the patient that the recommended dose is taken weekly for psoriasis.
Due to diminished hepatic and renal function as well as decreased folate stores in this population, relatively low doses (especially in RA and psoriasis indications) should be considered and these patients should be closely monitored for early signs of toxicity (see Precautions).