Thioguanine

INTRODUCTION

Indications

Induction and consolidation of remission in acute nonlymphocytic leukemia (in combination with other agents).

Action

Incorporated into DNA and RNA, subsequently disrupting synthesis (cell-cycle S phase–specific). Therapeutic Effects: Death of rapidly replicating cells, especially malignant ones. Immunosuppressive properties.

Adverse Reactions/Side Effects

EENT: loss of vibratory sense. GI: diarrhea, hepatotoxicity, jaundice, nausea, stomatitis, vomiting, anorexia, hepatic veno-occlusive disease. GU: gonadal suppression. Derm: dermatitis, rash. Hemat: anemia, leukopenia, thrombocytopenia, pancytopenia. Metab: hyperuricemia. Neuro: unsteady gait.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Watch for signs of leukopenia (fever, sore throat, signs of infection), thrombocytopenia (bruising, nose bleeds, bleeding gums), or unusual weakness and fatigue that might be due to anemia or other blood dyscrasias. Report these signs to the physician.

• Monitor vibratory sensation. Report loss of vibratory sense or other sensory dysfunction.

• Assess gait, and notify physician and family/caregivers if patient is not safe when ambulating independently.

Interventions

• For patients who are medically able to begin exercise, implement appropriate resistive exercises and aerobic training to maintain muscle strength and aerobic capacity during cancer chemotherapy or to help restore function after chemotherapy.

• Provide gait training and balance activities. Guard against falls and trauma due to unsteady gait (See Appendix E).

Patient/Client-Related Instruction

• Advise patient to decrease risk of infections (frequent hand washing, etc.) and avoid contact with persons with contagious diseases.

• Advise patient about the likelihood of GI reactions, including nausea, vomiting, diarrhea, and inflammation in or around the mouth. Instruct patient to report severe or prolonged GI problems, and to also report signs of hepatotoxicity such as anorexia, abdominal pain, severe nausea and vomiting, yellow skin or eyes, fever, sore throat, malaise, weakness, facial edema, lethargy, and unusual bleeding or bruising.

• Advise patient that rashes, dermatitis, and other skin reactions are likely. Report severe or unexpected skin reactions to the physician.

Pharmacokinetics

Absorption: Variable and incomplete (average, 30%) following oral administration.

Distribution: Probably does not enter the CSF. Crosses the placenta.

Metabolism and Excretion: Highly metabolized by the liver.

Half-life: 11 hr.

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Pregnancy or lactation; Tumors with demonstrated resistance to thioguanine or mercaptopurine (usually complete cross-resistance).

Use Cautiously in: Patients with childbearing potential; Infections; Decreased bone marrow ...