Allopurinol

(AL-oh-PURE-ee-nahl)

  Action:
Inhibits xanthine oxidase, the enzyme responsible for conversion of hypoxanthine to xanthine and then to uric acid.

  Indications:

Tablets: Treatment of primary or secondary gout, hyperuricemia resulting from chemotherapy for malignancies, recurrent calcium oxalate renal calculi.

Tablets and injections: Management of patients with leukemia, lymphoma, and solid tumor malignancies when concurrently receiving cancer therapy that causes elevations of serum and urinary uric acid levels. Use injection in patients who cannot tolerate oral therapy. Unlabeled use(s):Prevention of fluorouracil-induced stomatitis and fluorouracil-induced granulocyte suppression.

  Contraindications:
Standard considerations.

  Route/Dosage:

Control of Gout/Hyperuricemia

Adults:
PO 100 to 800 mg/day. For amounts > 300 mg, give divided doses.

Secondary Hyperuricemia Associated with Malignancies

Children 6 to 10 yr:
PO 300 mg/day.

Children < 6 yr:
PO 150 mg/day.

Prevention of Uric Acid Nephropathy in Vigorous Chemotherapy of Neoplastic Disease

Adults:
PO 600 to 800 mg/day for 2 to 3 days.

Reduction of Risk of Acute Gouty Attacks

Adults: Initial dose:
PO 100 mg/day, increased by 100 mg at weekly intervals until adequate response is achieved or max recommended dose (800 mg/day) is reached.

Leukemia, Lymphoma, Solid Tumor Malignancies

Adults:
IV 200 to 400 mg/m²/day (max 600 mg/day).

Children:
IV Starting dose 200 mg/m²/day.

  Interactions:

Aluminum salts, uricosuric agents: May lessen effectiveness of allopurinol.

Ampicillin: May increase incidence of ampicillin-induced skin rash.

Cyclophosphamide: May enhance bone marrow suppression.

Theophyllines: Theophylline clearance may be decreased, leading to toxicity.

Thiopurines (eg, azathioprine, mercaptopurine): Toxicity of these drugs may be increased.

Drugs that are physically incompatible in solution with allopurinol sodium for injection are the following: amikacin; amphotericin B; carmustine; cefotaxime; chlorpromazine; cimetidine; clindamycin; cytarabine; dacarbazine; daunorubicin; diphenhydramine; doxorubicin; doxycycline; droperidol; floxuridine; gentamicin; haloperidol; hydroxyzine; idarubicin; imipenem plus cilastain; mechlorethamine; meperidine; metoclopramide; methylprednisolone sodium succinate; minocycline; nalbuphine; netilmicin; ondansetron; prochlorperazine edisylate; promethazine; sodium bicarbonate; streptozocin; tobramycin; vinorelbine tartrate.

  Lab Test Interferences:
None well documented.

  Adverse Reactions:

CNS:

Drowsiness; generalized seizure (injectable); headache; neuritis; paresthesias; peripheral neuropathy.

DERM:

Allergic vasculitis; alopecia; ecchymosis; skin rash. Allergic reactions may be severe and sometimes fatal.

EENT:

Epistaxis; myopathy; taste disturbance.

GI:

Abdominal pain; diarrhea; dyspepsia; gastritis; granulomatous changes; nausea; vomiting.

GU:

Renal failure; uremia.

HEMA:

Bone marrow depression; eosinophilia; leukocytosis; leukopenia; thrombocytopenia.

HEPA:

Cholestatic jaundice; elevated liver enzymes; hepatic necrosis; hepatitis; reversible hepatomegaly.

OTHER:

Acute gouty attacks; arthralgia; fever; myopathy; necrotizing angiitis.

  Precautions:

Pregnancy: Category C.

Lactation: Excreted in breast milk.

Children: Allopurinol is rarely indicated for use in children, except for hyperuricemia resulting from malignancy or with certain rare inborn errors of purine metabolism.

Acute gouty attacks: May occur during initial stages of therapy.

Bone marrow depression: Reported in patients given allopurinol.

Hypersensitivity: Discontinue drug at first appearance of skin rash or other signs of allergic reaction. Rash may be followed by more severe hypersensitivity reactions and, rarely, death.

Renal function impairment: Reduced dose is given in patients with this condition. Drug may exacerbate renal failure in certain patients.

  Administration/Storage:

• Administer immediately after meals. For patients who have difficulty swallowing, crush tablets and mix with food.
• Store tablets in tightly closed container in cool location.
• Store unreconstituted powder at room temperature.
• Store reconstituted solution at 20° to 25°C; do not refrigerate or dilute product.

  Assessment/Interventions:

• Obtain patient history, including drug history and any known allergies.
• Assess for renal toxicity and failure.
• Increase fluid intake to 2000 to 3000 mL/day (unless contraindicated) to prevent calculi formation.
• Obtain baseline CBC. Monitor frequently.
• For treatment of gout, obtain baseline uric acid level. Monitor q 1 to 2 wk for dosage adjustment, then monitor every few months.
• Monitor liver and kidney function, including BUN, serum creatinine, and Ccr, especially during early therapy.
• Monitor for decrease in joint swelling and pain.
• If urine output is decreased, dosage may need to be decreased. Consult health care provider.

  Patient/Family Education:

• Encourage patient to focus on weight loss or control.
• Tell patient to avoid purine-rich foods (eg, organ meats).
• Caution patient to avoid excessive intake of alcohol.
• Explain that gouty attacks may not end for 2 to 6 wk after beginning therapy.
• Instruct patient to stop taking medication and notify health care provider if rash or flu-like symptoms develop.
• Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.
• Instruct patient not to take otc medications without consulting health care provider.

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