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Reditrex Injection

--> Rheumatoid Arthritis including Polyarticular Juvenile Idiopathic Arthritis

RediTrex is indicated in the management of selected adults with severe, active rheumatoid arthritis (RA) (ACR criteria), or children with active polyarticular juvenile idiopathic arthritis (pJIA), who have had an insufficient therapeutic response to, or are intolerant of, an adequate trial of first-line therapy including full dose non-steroidal anti-inflammatory agents (NSAIDs).


RediTrex is indicated in adults for the symptomatic control of severe, recalcitrant, disabling psoriasis that is not adequately responsive to other forms of therapy, but only when the diagnosis has been established, as by biopsy and/or after dermatologic consultation. It is important to ensure that a psoriasis "flare" is not due to an undiagnosed concomitant disease affecting immune responses.

Limitation of Use

RediTrex is not indicated for the treatment of neoplastic diseases.

Reditrex Injection Dosage and Administration Important Dosing Information

RediTrex is a single-dose prefilled syringe (in a needle safety device) for once-weekly subcutaneous use only [see Warnings and Precautions (5.5)]. Administer RediTrex in the abdomen or the thigh. RediTrex is available in the following dosage strengths: 7.5, 10, 12.5, 15, 17.5, 20, 22.5 and 25 mg. Use another formulation of methotrexate for alternative dosing in patients who require oral, intramuscular, intravenous, intra-arterial, intrathecal dosing, doses less than 7.5 mg per week, doses more than 25 mg per week, high-dose regimens, or dose adjustments of less than 2.5 mg increments.

Rheumatoid Arthritis including Polyarticular Juvenile Idiopathic Arthritis

Recommended starting dose of methotrexate:

Adult RA: 7.5 mg once weekly.

pJIA: 10 mg/m2 once weekly.

For patients switching from oral methotrexate to RediTrex, consider any differences in bioavailability between oral and subcutaneously administered methotrexate [see Clinical Pharmacology (12.3)].

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. 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 RediTrex therapy [see Warnings and Precautions (5.4)]. Females of childbearing potential should not be started on RediTrex until pregnancy is excluded [see Contraindications (4) and Warnings and Precautions (5.2)].

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.

Maximal myelosuppression usually occurs in seven to ten days.


Recommended starting dose of methotrexate:

Psoriasis: single weekly oral, intramuscular, subcutaneous, or intravenous doses of 10-25 mg.

For patients switching from oral methotrexate to RediTrex, consider any differences in bioavailability between oral and subcutaneously administered methotrexate [see Clinical Pharmacology (12.3)].

Dosage may be gradually adjusted to achieve optimal clinical response; 30 mg/week should not ordinarily be exceeded. Once optimal clinical response has been achieved, the dosage should be reduced to the lowest possible amount of drug and to the longest possible rest period. The use of RediTrex may permit the return to conventional topical therapy, which should be encouraged.

Administration and Handling

RediTrex is a prefilled syringe intended for subcutaneous use under the guidance and supervision of a physician.

Patients may self-inject with RediTrex if a physician determines that it is appropriate, if they have received proper training in how to prepare and administer the correct dose, and if they receive medical follow-up, as necessary.

Visually inspect RediTrex for particulate matter and discoloration prior to administration.

Handle and dispose of RediTrex consistent with recommendations for handling and disposal of cytotoxic drugs1.

Pregnancy testing

Verify the pregnancy status of females of reproductive potential prior to initiating treatment with RediTrex [see Use in Specific Populations (8.1, 8.3)]

Dosage Forms and Strengths

RediTrex contains methotrexate in a sterile, preservative-free, solution in a pre-filled syringe (in a needle safety device) with a 29 gauge ½ inch needle for a single subcutaneous injection. RediTrex solution is yellow in color. RediTrex is available at a concentration of 25 mg/mL to administer the following doses of methotrexate solution:

  • 7.5 mg
  • 10 mg
  • 15 mg
  • 17.5 mg
  • 20 mg
  • 22.5 mg
  • 25 mg

RediTrex is contraindicated in the following:

  • Pregnancy

RediTrex can cause embryo-fetal toxicity and fetal death when administered during pregnancy. [see Warnings and Precautions (5.2), Use in Specific Populations (8.1)].

  • Alcoholism or Liver Disease

Patients with alcoholism, alcoholic liver disease or other chronic liver disease [see Warnings and Precautions (5.1)].

  • Immunodeficiency Syndromes

Patients who have overt or laboratory evidence of immunodeficiency syndromes [see Warnings and Precautions (5.1)].

  • Preexisting Blood Dyscrasias

Patients who have preexisting blood dyscrasias, such as bone marrow hypoplasia, leukopenia, thrombocytopenia, or significant anemia [see Warnings and Precautions (5.1)].

  • Hypersensitivity

Patients with a known hypersensitivity to methotrexate. Severe hypersensitivity reactions have been observed with methotrexate use [see Warnings and Precautions (5.1) and Adverse Reactions (6.1 and 6.2)].

Warnings and Precautions Organ System Toxicity

RediTrex should be used only by physicians whose knowledge and experience include the use of antimetabolite therapy. Because of the possibility of serious toxic reactions (which can be fatal), RediTrex should be used only in patients with psoriasis or rheumatoid arthritis with severe, recalcitrant, disabling disease which is not adequately responsive to other forms of therapy.

Deaths have been reported with the use of methotrexate in the treatment of malignancy, psoriasis, and rheumatoid arthritis. Patients should be closely monitored for bone marrow, liver, lung and kidney toxicities.

RediTrex has the potential for serious toxicity. Toxic effects may be related in frequency and severity to dose or frequency of administration but have been seen at all doses. Because they can occur at any time during therapy, it is necessary to follow patients on RediTrex closely. Most adverse reactions are reversible if detected early. When such reactions do occur, the drug should be reduced in dosage or discontinued and appropriate corrective measures should be taken. If necessary, this could include the use of leucovorin calcium and/or acute, intermittent hemodialysis with a high-flux dialyzer [see Overdosage (10)]. If RediTrex therapy is reinstituted, it should be carried out with caution, with adequate consideration of further need for the drug and increased alertness as to possible recurrence of toxicity. The clinical pharmacology of methotrexate has not been well studied in older individuals. Due to diminished hepatic and renal function as well as decreased folate stores in this population, relatively low doses should be considered, and these patients should be closely monitored for early signs of toxicity [see Use in Specific Populations (8.5)].


Diarrhea and ulcerative stomatitis require interruption of therapy: otherwise, hemorrhagic enteritis and death from intestinal perforation may occur.

If vomiting, diarrhea, or stomatitis occur, which may result in dehydration, RediTrex should be discontinued until recovery occurs. RediTrex should be used with extreme caution in the presence of peptic ulcer disease or ulcerative colitis.

Unexpectedly severe (sometimes fatal) gastrointestinal toxicity has been reported with concomitant administration of methotrexate (usually in high dosage) along with some nonsteroidal anti-inflammatory drugs (NSAIDs) [see Drug Interactions (7.1)].


RediTrex can suppress hematopoiesis and cause anemia, aplastic anemia, pancytopenia, leukopenia, neutropenia, and/or thrombocytopenia. In patients with preexisting hematopoietic impairment, RediTrex should be used with caution, if at all. In controlled clinical trials conducted with another formulation of methotrexate in rheumatoid arthritis (n=128), leukopenia (WBC

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