General Info:

For which conditions is this drug approved?

Allopurinol is FDA approved for management of patients with cancer who are receiving cancer therapy that causes elevations of uric acid levels in association with tumor lysis syndrome.
It is important for patients to remember that physicians have the ability to prescribe medication for conditions other than those for which the drug has been approved by the FDA. Patients who have received a prescription of this drug for a condition other than which it is approved may wish to discuss this issue with their physician.

What is the mechanism of action?

Allopurinol works by reducing the formation of uric acid.

Tumor lysis syndrome (TLS) is the development of electrolyte and metabolic disturbances that may occur following the treatment of cancer and can result in life-threatening complications if not managed appropriately. TLS is caused by the sudden, rapid death of cells, particularly cancer cells in patients with leukemia or lymphoma, in response to cancer therapies. TLS may occur spontaneously, although this is uncommon. When cancer cells are killed by therapy, they spill their inner (intracellular) contents, which accumulate in the body faster than can be eliminated. These intracellular contents cause the metabolic and electrolyte disturbances that result in TLS. Hyperuricemia is a component of TLS and refers to excess uric acid in the blood. Uric acid is the end product of the digestion of certain proteins and is normally eliminated through the urine. When excess uric acid is present, it is converted to crystals formed of sodium urate. These crystals may deposit in the tiny tubes that are part of the kidney and cause acute kidney damage, which can ultimately lead to kidney failure.

How is allopurinol typically given (administered)?

Allopurinol is usually given orally as a tablet, but also may be given intravenously (into a vein). Patients taking the oral tablet will take the tablet after a meal and with plenty of fluid. Patients may have an allergic-type reaction to treatment with allopurinol, although this is uncommon. Patients should tell their healthcare provider immediately at the first signs of a rash or other skin abnormalities, as more severe side effects may follow.

How are patients typically monitored?

Patients will usually have scheduled meetings with their healthcare provider while they are being treated with allopurinol. Typically, blood will be drawn to check levels of blood cells and to monitor functions of some organ systems, such as the kidneys or liver. Patients may also undergo physical examinations, scans or other measures to assess side effects and response to therapy. In addition, levels of electrolytes and products of metabolism will be measured frequently to monitor the possibility of developing TLS. Patients will also be monitored for allergic-type reactions that may occur with treatment with allopurinol, including skin abnormalities and liver dysfunction.

What are the most common side effects associated with treatment with allopurinol?

• Skin rash
• Nausea and vomiting
• Abnormalities of the kidneys
• Diarrhea

This is not a complete list of side effects. Some patients may experience other side effects that are not listed here. Patients may wish to discuss with their physician the other less common side effects of this drug, some of which may be serious.

Some side effects may require medical attention. Other side effects do not require medical attention and may go away during treatment. Patients should check with their physician about any side effects that continue or are bothersome.

What can patients do to help alleviate or prevent discomfort and side effects?

• Pay careful attention to the physician's instructions and inform the physician of any side effects.
• Wear sunscreen and protective clothing and try to minimize sun exposure.
• Drink plenty of fluids. (Patients should ask their physician about the amount of liquid to consume during a day.)
• Maintain adequate rest and nutrition.
• Eat small meals frequently to help alleviate nausea.