Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Abnormal heart rhythms: Vandetanib may cause a heart rhythm problem called QT prolongation. Sudden death has been reported in patients taking this medication. If you have a history of QT prolongation, slow or irregular heart beat, irregular heart rhythm, heart failure, heart attack, heart disease, taking other medications known to cause QT prolongation, or a family history of sudden cardiac death at less than 50 years of age, discuss with your doctor how this medication may affect your medical condition, or how your medical condition may affect the dosing and effectiveness of this medication. Your doctor will perform tests at regular intervals to monitor for any changes in your heart rhythm.
Bleeding: This medication can reduce the number of platelet cells in the blood. Platelets help the blood to clot, and a shortage could make you bleed more easily. Tell your doctor of any signs that your blood is not clotting as quickly as usual. Such symptoms may include black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding.
Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including platelets, in your blood.
Drowsiness/reduced alertness: This medication may cause drowsiness or blurred vision. If you are feeling tired or weak or you have blurred vision while taking vandetanib, avoid driving, operating machinery and doing other tasks that require alertness.
Fluid and electrolyte balance: Vandetanib may cause the levels of electrolytes such as potassium, magnesium, and calcium in the blood to change while taking this medication. If you experience symptoms of fluid and electrolyte imbalance such as muscle pains or cramps; dry mouth; numb hands, feet, or lips; or racing heartbeat, contact your doctor as soon as possible. Your doctor will do blood tests regularly to monitor the levels of these electrolytes in your blood while you are taking this medication.
Grapefruit juice: Grapefruit juice affects how vandetanib is removed from the body. It may cause too much of the medication to build up in the body and cause possibly harmful side effects. Do not drink grapefruit juice or eat grapefruit at any time while taking this medication.
Heart failure: People taking vandetanib have experienced heart failure (the heart is not able to pump blood efficiently). This may be accompanied by fluid retention (see below) or fluid in the lungs (pulmonary edema). If you experience shortness of breath, chest pain, swelling, or weight gain, contact your doctor immediately.
High blood pressure: Vandetanib can cause increased blood pressure, which may become dangerously high and cause stroke. If blood pressure cannot be controlled, the dose of this medication may need to be decreased.
Infection: As well as killing cancer cells, vandetanib can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.
Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Vandetanib has been reported to cause decreased liver function and, in some cases, liver failure that has caused death. If you have a history of liver disease or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. This medication is not recommended for people with moderately to severely reduced liver function.
If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.
Lung inflammation: Lung inflammation (interstitial lung disease) causing difficulty breathing has occurred on rare occasions in some people taking this medication. This complication can be serious and sometimes fatal. If you experience new or worsening shortness of breath or cough (with or without fever) at any time while you are taking vandetanib, contact your doctor immediately.
Reversible posterior leukoencephalopathy syndrome (RPLS): This is a rare disease of the brain that may occur when using medications like vandetanib. If you have had a previous episode of RPLS, vandetanib may not be an appropriate medication for you. Make sure your doctor knows you have experienced this before. If you experience signs and symptoms of RPLS, such as headache, seizures, change in awareness or consciousness or vision changes, contact your doctor immediately.
Skin sensitivity: This medication may increase the sensitivity of the skin to sunlight, increasing the risk of sunburn. Wear protective clothing and sunblock while taking vandetanib and for 4 months afterwards.
Vandetanib can also cause severe skin reactions that may be life-threatening. If you notice any unusual skin rash or peeling, a rash that develops quickly or develops with fever, contact your doctor immediately.
Thyroid function: This medication may affect how thyroid hormone is used by your body. Some people who take thyroid hormone replacement need to have an increased dose of thyroid medication when they take vandetanib. If you have thyroid disease or have had your thyroid gland removed, discuss with your doctor how this medication may affect your medical condition. Your doctor may want to test your thyroid function regularly with blood tests while you are taking this medication.
Wound healing: Vandetanib may slow the speed at which wounds heal. Ensure any health care professionals, including dentists and other doctors, are aware that you are taking this medication.
Pregnancy: This medication may cause harm to an unborn fetus and should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately. Women of childbearing age who are taking vandetanib should use an effective method of birth control (e.g., birth control pill, condoms) during treatment and for at least 3 months after the last dose of vandetanib.
Men receiving this medication must use an effective method of contraception during treatment and for two months following the last dose.
Breast-feeding: It is not known if vandetanib passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
The safety and effectiveness of using this medication have not been established for children.