Generic Name

Thioguanine

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Classification

FDA Approved Indications

• Acute myeloid leukemia (AML)

Mechanism of Action

Thioguanine is a purine analogue that gets incorporated into DNA and RNA, inhibiting nucleic acid synthesis and leading to cell death, particularly of rapidly dividing cells such as leukemia cells.

Dosage and Administration

Adult: Dose varies based on treatment protocol; typically 40-120 mg/m²/day orally in divided doses

Pediatric: Dosing based on body surface area, similar to adult dosing

Geriatric: Dose adjustments may be necessary, start at lower doses due to potential increased toxicity

Renal Impairment: Use with caution; dosage adjustments may be required

Hepatic Impairment: Use with caution; dose adjustments may be necessary

Pharmacokinetics

Absorption: Well absorbed orally

Distribution: Widely distributed including into tissues and fluids

Metabolism: Metabolized in the liver to active and inactive metabolites

Excretion: Excreted in urine

Half Life: Approximately 1-3 hours, but pharmacodynamic effects last longer

Contraindications

• Hypersensitivity to thioguanine

Precautions

• Patients with active infections, hepatic dysfunction, or bone marrow suppression

Adverse Reactions - Common

• Bone marrow suppression (including leukopenia, anemia, thrombocytopenia) (Common)
• Nausea, vomiting (Common)
• Mucositis (Common)

Adverse Reactions - Serious

• Myelosuppression leading to increased infection risk (Serious)
• Hepatotoxicity, including hepatic veno-occlusive disease (Serious)
• Secondary malignancies (rare) (Rare)

Drug-Drug Interactions

• Allopurinol increases thioguanine levels, increasing toxicity; monitoring required

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Report signs of infection, bleeding, or unusual bruising promptly
• Use effective contraception due to teratogenic potential
• Follow blood test schedules diligently

Special Considerations

Black Box Warnings:

• Potential for severe myelosuppression which can be fatal
• Risk of secondary malignancies

Genetic Factors: Thiopurine methyltransferase (TPMT) activity affects metabolism; testing recommended

Lab Test Interference: May interfere with certain laboratory tests involving nucleic acids

Overdose Management

Signs/Symptoms: Severe bone marrow suppression, bleeding, infection

Treatment: Supportive care, including blood products, antibiotics, and growth factors as needed; no specific antidote

Storage and Handling

Storage: Store at room temperature, away from light and moisture

Stability: Stable until expiration date on packaging