Vandetanib belongs to the group of cancer-fighting medications known as antineoplastics and more specifically to a class of medications called receptor tyrosine kinase inhibitors. These medications are antitumour medications that slow the growth of blood vessels that feed nutrients to cancer cells. By slowing the growth of these blood vessels, vandetanib can help reduce the size of tumours, which are collections of cancer cells. Vandetanib also works directly on cancer cells to kill them or slow down the speed at which they grow.

This medication is used to treat medullary thyroid cancer that is progressing or causing symptoms and where surgery is not an option or that has become metastatic (spread to other parts of the body). This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The regular adult dose of vandetanib is 300 mg taken by mouth, once daily. This medication should be taken at approximately the same time each day, and may be taken with or without food.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Vandetanib tablets should not be crushed, as this medication is irritating to the skin and soft tissue in the mouth. If you are not able to swallow these tablets whole, you may drop the whole tablet in half a glass of plain water and stir until it is dissolved (approximately 10 minutes). Drink the solution immediately. To make sure there is no medication left in the glass, add another half glass of water to the empty glass and drink that as well. Use only plain, uncarbonated water and do not crush the tablets.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, and it is 12 hours or more before your next dose, take the missed dose as soon as possible and continue with your regular schedule. If it is less than 12 hours until your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

100 mg
Each round, white, biconvex, film-coated tablet, impressed with "Z100" on one side and plain on the other, contains 100 mg of vandetanib. Nonmedicinal ingredients: calcium hydrogen phosphate dihydrate, crospovidone, hypromellose 2910, macrogol 300, magnesium stearate, microcrystalline cellulose, povidone, and titanium dioxide E171.

300 mg
Each oval, white, biconvex, film-coated tablet, impressed with"Z300" on one side and plain on the other, contains 300 mg of vandetanib. Nonmedicinal ingredients: calcium hydrogen phosphate dihydrate, crospovidone, hypromellose 2910, macrogol 300, magnesium stearate, microcrystalline cellulose, povidone, and titanium dioxide E171.

Do not take vandetanib if you:

• are allergic to vandetanib or any ingredients of the medication
• have long QT syndrome (a type of irregular heartbeat)
• have high blood pressure that is not controlled
• have uncorrected low levels of potassium, magnesium or calcium in your blood

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• acne
• back or joint pain
• changes in the way things taste
• cough
• diarrhea
• dry eyes
• dry mouth
• feeling tired, lack of energy
• hair loss
• headache
• increased sensitivity to sunlight
• indigestion
• loss of appetite
• mouth sores
• mild skin rash
• muscle weakness
• nausea
• nail problems
• red, irritated eyes
• stomach pain
• tremor
• trouble sleeping
• vision changes
• vomiting
• weight loss

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• confusion, difficulty thinking
• dizziness
• fainting
• high blood pressure
• numbness, tingling, or rash of the hands or feet
• severe diarrhea

• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)

• signs of bleeding (e.g., nose bleeds, blood in urine, coughing blood, cuts that don't stop bleeding)
• signs of dehydration (e.g., thirst, dry mouth, poor tear production, decreased need to urinate)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of heart rhythm changes (e.g., dizziness, fainting, rapid heartbeat, pounding heartbeat)

• signs of kidney problems (e.g., change in the amount or colour of urine, increased urination at night, blood in the urine, swelling in the feet or legs)

• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)

• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)

• slowed wound healing
• swelling of the ankles or feet
• symptoms of appendicitis (e.g., sudden abdominal pain that worsens with walking or cough, nausea, vomiting)
• symptoms of hand-foot syndrome (e.g., red, swollen balms, thick calluses and blisters on the hands and soles of the feet, tingling or burning feeling, skin tightness)
• symptoms of gallbladder inflammation (e.g., fever, nausea, pain radiating to shoulder or back, severe abdominal pain, vomiting)

• symptoms of glaucoma (e.g., blurred vision, seeing halos of bright colours around lights, red eyes, increased pressure in your eyes, eye pain or discomfort)

• symptoms of kidney stones (e.g., severe pain, nausea, vomiting, blood in the urine, fever, and chills)
• symptoms of laryngitis (e.g., sore or ticklish throat, difficulty swallowing, voice changes, hoarseness)

• symptoms of pneumonia (e.g., fever, chills, shortness of breath, cough)
• symptoms of an upper respiratory tract infection (e.g., congested or runny nose, cough, headache, fatigue)
• symptoms of a urinary tract infection (e.g., pain when urinating, urinating more often than usual, lower back or flank pain)

• worsening cough or shortness of breath

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• seizures
• signs of artery dissection (sudden severe pain in the chest, back, or abdomen)
• signs of aneurysm; bulge in the wall of any artery (e.g., chest, arm, leg, brain, heart – cough, coughing blood, unusual pain high in neck or back, problems swallowing, pulsing sensation in chest or abdomen)
• signs of heart failure (e.g., difficulty breathing, rapid or irregular heartbeat, shortness of breath)

• signs of sepsis (blood infection; e.g., fever, dizziness, chills, very high or very low body temperature, low blood pressure, pounding or rapid heartbeat, rapid, shallow breathing)

• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

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 by patients taking this medication. If you have a history of QT prolongation, slow or irregular heartbeat, 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. Vandetanib can also cause severe diarrhea which can affect electrolyte balance. 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.

Other fruits that should be avoided for similar reasons include starfruit, pomegranate, and Seville oranges.

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 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 for 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 2 months following the last dose.

Breast-feeding: It is not known if vandetanib passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

There may be an interaction between vandetanib and any of the following:

• alfuzosin
• amiodarone
• antiarrhythmics (e.g., amiodarone, disopyramide, dronedarone, flecainide, procainamide, propafenone)
• anticancer medications (e.g., capecitabine, fluorouracil, inotuzumab, oxaliplatin)
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apalutamide
• apomorphine
• atomoxetine
• azole antifungals (e.g., fluconazole, itraconazole, voriconazole)
• beta-adrenergic agonists (e.g., formoterol, indacaterol, olodaterol, salmeterol)
• bilastine
• bisphosphonates (e.g., alendronate, risedronate)
• bosentan
• buprenorphine
• buserelin
• danazol
• degarelix
• digoxin
• domperidone
• donepezil
• eliglustat
• enzalutamide
• fosphenytoin
• general anesthetics (medications to put you to sleep for surgery)
• goserelin
• grapefruit juice
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, rilpivirine)
• hydroxychloroquine
• hydroxyzine
• leuprolide
• lithium
• loperamide
• lumacaftor and ivacaftor
• macrolide antibiotics (e.g., azithromycin, clarithromycin, erythromycin)
• mefloquine
• metformin
• methadone
• metoclopramide
• metronidazole
• mifepristone
• mirtazapine
• mitotane
• modafinil
• pentamidine
• pitolisant
• primaquine
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, levofloxacin, moxifloxacin)
• ranolazine
• rifabutin
• rifampin
• romidepsin
• St. John's wort
• seizure medications (e.g., carbamazepine, eslicarbazepine, phenytoin, primidone)
• selective 5-HT receptor antagonists (e.g.,  granisetron, ondansetron)
• selective serotonin inhibitors (SSRIs; e.g., citalopram, escitalopram, fluoxetine, sertraline)
• solifenacin
• somatostatin analogues (e.g., lanreotide, octreotide, pasireotide)
• sotalol
• sphingosine 1-phosphate (S1P) receptor inhibitors (e.g., fingolimod, ponesimod, siponimod)
• tacrolimus
• tamoxifen
• testosterone
• tetrabenazine
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, desipramine, doxepin, imipramine, nortriptyline)
• triptorelin
• other tyrosine kinase inhibitors (e.g., ceritinib, dabrafenib, dasatinib, nilotinib)
• vardenafil
• vorinostat

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.