| THIOGUANINE (TG, 6-THIOGUANINE)
Lanvis , Tabloid
Classifications: antineoplastic; antimetabolite; purine antagonist; Therapeutic: antineoplastic; antimetabolite
Pregnancy Category: D
40 mg tablets
Antimetabolite and purine antagonist with immunosuppressive activity. Highly toxic. Drug is incorporated into the DNA and
RNa of human bone marrow cells.
Delays myelosuppression; has potential mutagenic and carcinogenic properties.
In combination with other antineoplastics for remission induction in acute myelogenous leukemia and as treatment of chronic
myelogenous leukemia. Has little advantage over mercaptopurine.
Patients with prior resistance to this drug; severe bone marrow depression; pregnancy (category D), lactation.
Route & Dosage
Adult: PO 2 mg/kg/d, may increase to 3 mg/kg/d if no response after 4 wk
- Withhold drug and notify physician if toxicity develops. There is no known antagonist; prompt discontinuation of the drug
is essential to avoid irreversible myelosuppression from toxicity.
- Store at 15°30° C (59°86° F) in airtight container.
Adverse Effects (≥1%)Hematologic: Leukopenia, thrombocytopenia, anemia
. GI: Jaundice
, nausea, vomiting, anorexia, stomatitis
. Urogenital: Hyperuricemia. Other:
Hepatotoxicity (risk increased with long-term use).
Severe hepatotoxicity with busulfan;
may decrease immune response
; increase risk of bleeding with anticoagulants
; platelet inhibitors
, thrombolytic agents
; effects may be reversed by filgrastim, sargramostim.
Variable and incomplete absorption from GI tract. Peak:
8 h. Distribution:
Crosses placenta. Metabolism:
In liver. Elimination:
In urine. Half-Life:
Assessment & Drug Effects
- Lab tests: Monitor blood counts weekly (CBC with differential and platelet count); periodic LFTs with long-term use.
- Determine hematologic parameters for withholding drug.
- Monitor I&O ratio and report oliguria.
- Observe patient's skin and sclera for jaundice. It should be reported promptly as a symptom of toxicity; drug will be discontinued
- Expect that the drop in leukocyte count may be slow over a period of 24 wk. Treatment is interrupted if there is a
rapid fall within a few days.
Patient & Family Education
- Maintenance doses are continued throughout remissions.