For either adult RA or polyarticular-course JRA dosages may be adjusted gradually to achieve an optimal response. Limited experience shows a significant increase in the incidence and severity of serious toxic reactions, especially bone marrow suppression, at doses greater than 20 mg/wk in adults. Although there is experience with doses up to 30 mg/m2/wk in children, there are too few published data to assess how doses over 20 mg/m2/wk might affect the risk of serious toxicity in children. Experience does suggest, however, that children receiving 20 to 30 mg/m2/wk (0.65 to 1.0 mg/kg/wk) may have better absorption and fewer gastrointestinal side effects if methotrexate is administered either intramuscularly or subcutaneously.

Therapeutic response usually begins within 3 to 6 weeks and the patient may continue to improve for another 12 weeks or more.

The optimal duration of therapy is unknown. Limited data available from long-term studies in adults indicate that the initial clinical improvement is maintained for at least two years with continued therapy. When methotrexate is discontinued, the arthritis usually worsens within 3 to 6 weeks.

The patient should be fully informed of the risks involved and should be under constant supervision of the physician. (See Information for Patients under PRECAUTIONS). Assessment of hematologic, hepatic, renal, and pulmonary function should be made by history, physical examination, and laboratory tests before beginning, periodically during, and before reinstituting methotrexate therapy. (See PRECAUTIONS). Appropriate steps should be taken to avoid conception during methotrexate therapy (See PRECAUTIONS and CONTRAINDICATIONS).

All schedules should be continually tailored to the individual patient. An initial test dose may be given prior to the regular dosing schedule to detect any extreme sensitivity to adverse effects (See ADVERSE REACTIONS). Maximal myelosuppression usually occurs in 7 to 10 days.

 Psoriasis

Recommended Starting Dose Schedule

1. Weekly single oral, IM or IV dosage schedule: 10 to 25 mg per week until adequate response is achieved.2
2. Divided oral dose schedule: 2.5 mg at 12 hour intervals for three doses.2

Dosages in each schedule may be gradually adjusted to achieve optimal clinical response; 30 mg/week should not ordinarily be exceeded.

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.

Methotrexate Sodium Tablets for oral administration are available.

 Handling and Disposal

Procedures for proper handling and disposal of anticancer drugs should be considered. Several guidelines on this subject have been published.1-7 There is no general agreement that all of the procedures recommended in the guidelines are necessary or appropriate.

 Dilution Instructions for Liquid Methotrexate Injection

Isotonic liquid, preservative free, for single use only.

If desired, the solution may be further diluted immediately prior to use with an appropriate sterile, preservative free medium such as 5% dextrose solution, USP or sodium chloride injection, USP.

Parenteral drug products should be inspected visually for particu