• Acute lymphoblastic leukemia.

Unlabeled Uses:

• Treatment of:
  • Some lymphomas,
  • Polycythemia vera,
  • Crohn's disease,
  • Psoriatic arthritis.

Contraindicated in:

• Hypersensitivity
• Severe hepatic impairment
• OB: Pregnancy
• Lactation: Lactation.

Use Cautiously in:

• Infection
• ↓bone marrow reserve
• Patients with homozygous TPMT enzyme deficiency or NUDT15 deficiency (substantial dose ↓ are required to avoid hematologic adverse events)
• Women of reproductive potential
• Geri: Older adults have ↑ risk of adverse reactions.

Derm: alopecia, hyperpigmentation.

Endo: gonadal suppression.

GI: anorexia, diarrhea, HEPATOSPLENIC T-CELL LYMPHOMA, HEPATOTOXICITY, nausea, vomiting.

GU: oligospermia.

Hemat: anemia, leukopenia, thrombocytopenia, MACROPHAGE ACTIVATION SYNDROME.

Metab: hyperuricemia.

Neuro: weakness.
Misc: fever, SECONDARY MALIGNANCY.

Drug-Drug:

• Allopurinol may ↑ risk of toxicity (↓ dose of mercaptopurine to 25–33% of the usual dose).
• A similar effect may occur with olsalazine, sulfasalazine, and mesalamine.
• May ↑ risk of bleeding with warfarin.
• ↑risk of hepatotoxicity with other hepatotoxic agents.
• ↑bone marrow depression with trimethoprim/sulfamethoxazole, other antineoplastics, or radiation therapy.
• May alter the effect of warfarin.
• ↓antibody response to live-virus vaccines and ↑ risk of adverse reactions.

Drug-Natural Products:

• Concomitant use with echinacea and melatonin may interfere with immunosuppression.

(Generic available)

• Tablets: 50 mg;
• Oral suspension (raspberry flavor): 20 mg/mL;

• PO (Adults): 1.5–2.5 mg/kg/day as a single dose.
• PO (Children): 2.5 mg/kg/day (75 mg/m²) single dose or divided doses (dose should be rounded to the nearest 25 mg).

Purixan

• Disrupts DNA and RNA synthesis (cell-cycle S-phase-specific).

• Death of rapidly proliferating cells, especially malignant ones.
• Also has immunosuppressant properties.

Therapeutic Classification: antineoplastics

Pharmacologic Classification: antimetabolites

Absorption: Variably and incompletely (5–50%) absorbed after oral administration.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Metabolized by liver. Converted to inactive metabolite by thiopurine methyltransferase (TPMT); nucleotide diphosphatase [NUDT15] is also involved in inactivation process. Nearly 50% is excreted unchanged by the kidneys.

Half-life: 1.3 hr.

Purinethol

(effects on blood counts)

• Explain purpose and side effects of medication to patient. Advise patient to read Patient Information before starting therapy. Emphasize the need for periodic lab tests to monitor for side effects. Take as directed. If dose is missed, take dose as scheduled; do not double dose.
• Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking other medications.
• Instruct patient to notify health care professional promptly if fever; chills; cough; hoarseness; sore throat; signs of infection; lower back or side pain; painful or difficult urination; bleeding gums; bruising; petechiae; blood in stools, urine, or emesis; ↑ fatigue; dyspnea; or orthostatic hypotension occur. Caution patient to avoid crowds and persons with known infections. Instruct patient to use soft toothbrush and electric razor and to avoid falls. Caution patient not to drink alcoholic beverages or take medication containing aspirin or NSAIDs; may precipitate gastric bleeding.
• Instruct patient to report yellowing of skin or eyes, anorexia, diarrhea, jaundice, ascites, dark-colored urine, clay-colored stools, abdominal pain, flank or joint pain, or swelling of feet or legs to health care professional promptly.
• Instruct patient not to receive any vaccinations without advice of health care professional.
• May cause fetal harm. Advise females of reproductive potential to use effective contraception during therapy and for 6 mo after last dose and to avoid breastfeeding during and for 1 wk after last dose of therapy. Advise males with female partners of reproductive potential to use effective contraception during and for 3 mo after last dose. May impair male and female fertility. May cause intrahepatic cholestasis of pregnancy (ICP) when used for inflammatory bowel disease. Discontinue therapy if ICP develops during pregnancy.

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