Key Terms: Anemia, Anthracyclines, Antineoplastics, Chemotherapy, Food and Drug Administration, Intravenous, Metastatic, Neutropenia, Radiation therapy, Sterility.
Definition
Dexrazoxane, known by the brand name Zinecard or may be referred to as ADR-529, is a medicine that protects the heart from damage caused by the chemotherapy drug doxorubicin.
Purpose
Dexrazoxane is approved by the Food and Drug Administration (FDA) as a protectant medicine given to women with metastatic breast cancer who are being treated with the chemotherapy drug doxorubicin. In most cases these women already will have received greater than 300 mg per square meter (mg/m2) of the chemotherapy drug doxorubicin before dexrazoxane is added. Dexrazoxane is given in combination with doxorubicin. Doxorubicin can cause damage to heart muscle and the risk of this damage increases as the total dose increases. The addition of dexrazoxane at the appropriate time in therapy can decrease the extent of damage to the heart muscle.
Description
Dexrazoxane is a clear, colorless solution. It is administered intravenously, into a vein, over a 15-30 minute period. Dexrazoxane is given within 30 minutes prior to receiving the doxorubicin. When doxorubicin gets into cells, it combines with iron to form toxic substances that destroy heart muscle. Dexrazoxane interferes with the doxorubicin binding to the iron compound so that the toxic substance is not formed and the heart muscle is protected.
Recommended Dosage
Dexrazoxane doses can be determined using a mathematical calculation that measures a person's body surface area (BSA). This number is dependent upon a patient's height and weight. The larger the person, the greater the body surface area. Body surface area is measured in units known as meters squared (m2). The body surface area is calculated and then multiplied by the drug dosage in mg/m2. This calculates the actual dose a patient is to receive.
Dexrazoxane is dosed in mg/m2 as a 10:1 ratio of the doxorubicin dose. For example, if a patient is to receive doxorubicin 50 mg/m2, then the patient would receive dexrazoxane 500 mg/m2. Once the dose is determined, the drug is administered either directly into the vein over a few minutes as an intravenous push, or as a quick infusion from an infusion bag. This is then followed by the doxorubicin intravenously.
Precautions
Blood counts will be monitored regularly while on dexrazoxane therapy. During a certain time period after receiving chemotherapy, there is an increased risk of getting infections. Caution should be taken to avoid unnecessary exposure to crowds and people with infections.
Patients should not expect their doctor to use dexrazoxane the first time they receive chemotherapy. It is thought that dexrazoxane may interfere with the chemotherapy drug's ability to destroy cancer cells. Dexrazoxane is therefore only used when absolutely necessary.
Patients who may be pregnant or are trying to become pregnant should tell their doctor before receiving dexrazoxane.
Chemotherapy can cause men and women to be sterile (not able to have children). It is unknown if dexrazoxane causes sterility.
Patients should check with their doctors before receiving live virus vaccines while on chemotherapy along with dexrazoxane.
Side Effects
The most common side effect from receiving the dexrazoxane is pain at the injection site. Another common side effect when dexrazoxane is given with chemotherapy is that the blood counts fall lower than with just chemotherapy alone. However, the time it takes for the blood counts to return to normal is the same with or without the dexrazoxane.
Low blood counts, referred to as myelosuppression, are expected due to chemotherapy with dexrazoxane administration. A low white blood cell count is called neutropenia, and patients are at an increased risk of developing a fever and infections. Platelets are blood cells in the body that allow for the formation of clots. When the platelet count is low, patients are at an increased risk for bruising and bleeding. Low red blood cell counts, referred to as anemia, may also occur due to chemotherapy administration. Low red counts cause fatigue.
Most other side effects occur due to the administration of the chemotherapy agents that accompany dexrazoxane. Common side effects include nausea and vomiting. Patients are given medicines before receiving chemotherapy that can help prevent or decrease these side effects from happening. Other common side effects are hair loss (alopecia), fatigue, loss of appetite, mouth sores, fevers, infections, diarrhea, and changes in liver function.
Less common side effects are nerve damage, swelling and inflammation of the veins where the chemotherapy is administered, difficulty swallowing, bleeding, itching, and skin reactions in areas of previous radiation.
All side effects a patient experiences should be reported to his or her doctor.
Interactions
Dexrazoxane should only be used with chemotherapy combinations that contain doxorubicin or other agents in the anthracycline class of antineoplastics.
Patients should tell their doctors if they have a known allergic reaction to dexrazoxane or any other medications or substances, such as foods and preservatives. Before taking any new medications, including nonprescription medications, vitamins, and herbal medications, the patients should notify their doctors.
—Nancy J. Beaulieu, RPh.,BCOP
