Methotrexate

INTRODUCTION

Indications

Alone or with other treatment modalities in the treatment of: Trophoblastic neoplasms (choriocarcinoma, chorioadenoma destruens, hydatidiform mole), Leukemias, Breast carcinoma, Head carcinoma, Neck carcinoma, Lung carcinoma. Treatment of severe psoriasis and rheumatoid arthritis unresponsive to conventional therapy. Treatment of mycosis fungoides (cutaneous T-cell lymphoma).

Action

Interferes with folic acid metabolism. Result is inhibition of DNA synthesis and cell reproduction (cell-cycle S-phase–specific). Also has immunosuppressive activity. Therapeutic Effects: Death of rapidly replicating cells, particularly malignant ones, and immunosuppression.

Adverse Reactions/Side Effects

CNS: arachnoiditis (IT use only), dizziness, drowsiness, headaches, malaise. EENT: blurred vision, dysarthria, transient blindness. Resp: PULMONARY FIBROSIS, intestinal pneumonitis. GI: anorexia, hepatotoxicity, nausea, stomatitis, vomiting. GU: infertility. Derm: alopecia, painful plaque erosions (during psoriasis treatment), photosensitivity, pruritus, rashes, skin ulceration, urticaria. Hemat: APLASTIC ANEMIA, anemia, leukopenia, thrombocytopenia. Metab: hyperuricemia. MS: osteonecrosis, stress fracture. Misc: nephropathy, chills, fever, soft tissue necrosis.

PHYSICAL THERAPY IMPLICATIONS

NOTE: Higher doses used to treat cancer will cause more numerous and severe reactions. Use of methotrexate to treat arthritis is at a much lower dose and frequency—often just once a week.

Examination and Evaluation

• Assess pulmonary function periodically by measuring lung volumes, breath sounds, and respiratory rate (See Appendices I, J, K). Notify physician immediately if patient experiences signs of pulmonary fibrosis or pneumonitis such as dry cough, dyspnea, shortness of breath, cyanosis, and fever.

• Monitor any unusual weakness and fatigue that might be due to aplastic anemia. Report signs of anemia or other blood dyscrasias such as leukopenia (fever, sore throat, signs of infection), or thrombocytopenia (bleeding gums; bruising; petechiae; blood in stools, urine, or emesis).

• Report signs of arachnoiditis, especially following IT administration. Signs include tingling, numbness, or weakness in the legs; strange sensations such as insects crawling on skin or water trickling down the legs; muscle cramps, spasms, or twitching; and bowel, bladder, or sexual dysfunction.

• Assess any musculoskeletal pain that might indicate osteonecrosis, stress fracture, or soft tissue necrosis. Report signs of musculoskeletal lesions and suggest the need for additional diagnostic testing (radiographs, MRI).

• If treating rheumatoid arthritis, periodically assess patient's impairments (pain, range of motion), functional ability, and disability to help document whether antirheumatic drug therapy is successful.

• If treating psoriasis or cutaneous fungal infections, assess healing of skin lesions to help document drug effectiveness.

• Assess dizziness (See Appendix C) that might affect gait, balance, and other functional activities. Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and ...