How does this medication work? What will it do for me?

Tucatinib belongs to the class of medications called antineoplastics (anticancer medications). Specifically, it is a protein kinase inhibitor. It is used in combination with other anticancer medications to treat metastatic (cancer that has spread to other parts of the body) breast cancer that is HER2-receptor positive and has progressed despite treatment with other anticancer medications.

Tucatinib works by interfering with the growth of certain cancer cells, slowing or stopping the growth of the tumour.

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.

What form(s) does this medication come in?

50 mg
Each round, convex, yellow, film-coated tablet, debossed with "TUC" on one side and "50" on the other side, contains 50 mg of tucatinib. Nonmedicinal ingredients: colloidal silicon dioxide, copovidone, crospovidone, potassium chloride, sodium bicarbonate, sodium chloride, magnesium stearate, and microcrystalline cellulose; coating: polyvinyl alcohol, titanium dioxide, macrogol/polyethylene glycol, talc, and non-irradiated yellow iron oxide.

150 mg
Each oval-shaped, yellow, film-coated tablet, debossed with "TUC" on one side and "150" on the other side, contains 50 mg of tucatinib. Nonmedicinal ingredients: colloidal silicon dioxide, copovidone, crospovidone, potassium chloride, sodium bicarbonate, sodium chloride, magnesium stearate, and microcrystalline cellulose; coating: polyvinyl alcohol, titanium dioxide, macrogol/polyethylene glycol, talc, and non-irradiated yellow iron oxide.

How should I use this medication?

The recommended dose of tucatinib is 300 mg (two 150 mg tablets) taken by mouth two times a day, along with trastuzumab and capecitabine. Tucatinib tablets should be swallowed whole with some water. Do not crush, chew, or split these tablets. They may be taken with or without food, and at the same time as capecitabine. Try to take the two doses 12 hours apart, at about the same time every day.

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.

It is important to take this medication exactly as prescribed by your doctor.

If you vomit after taking a dose of tucatinib, do not take another dose. Take your next dose at your usual dose time. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for 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 in its original container at room temperature. Protect it from light and moisture, and keep it out of the reach of children. If you have any medication remaining in the original container 3 months after opening the bottle, safely discard the medication.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you are allergic to tucatinib or any ingredients of the medication.

What side effects are possible with this medication?

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.

  • abdominal pain
  • decreased appetite
  • flu-like symptoms (e.g., fatigue, fever, sore throat, headache, sudden lack of energy)
  • hair loss
  • joint pain
  • low energy level
  • mouth sores
  • muscle weakness
  • nausea
  • night sweats
  • nosebleeds
  • open wounds or sores
  • redness or swelling in the mouth
  • trouble swallowing
  • 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:

  • accidental urination
  • bleeding from the rectum
  • chest discomfort or pain
  • diarrhea
  • fast, pounding heartbeat
  • fever
  • pain, tingling, or numbness in the hands or feet
  • painful urination
  • rash
  • signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
  • signs of dehydration (e.g., decreased urine, dry skin, dry and sticky mouth, sleepiness, dizziness, headache, thirst, confusion)
  • signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
  • signs of hand-foot syndrome (e.g., painful swelling, blistering, redness of the palms of the hands or soles of the feet)
  • signs of heart failure (e.g., fast, irregular heartbeat or pulse, chest pain, sudden weight gain, difficulty breathing, leg swelling)
  • 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)
  • symptoms of low blood pressure (e.g., dizziness or lightheadedness when rising from a sitting or lying position)
  • unexplained vaginal bleeding

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

  • seizures
  • symptoms of a severe infection (blood infection causing dangerously low blood pressure; fever, dizziness, chills, rapid breathing, fast heartbeat)

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.

Are there any other precautions or warnings for 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.

Birth control: The effects on the developing baby if either parent is taking tucatinib during pregnancy have not been determined. It is likely that exposure to tucatinib could cause harm to the baby. Women who could become pregnant and are taking tucatinib should use an effective method of birth control such as condoms during treatment and for 1 week after the last dose of this medication.

Men taking this medication who have partners who could become pregnant should use effective birth control during treatment and for 1 week after the last dose.

Diarrhea: This medication can cause diarrhea that can lead to dehydration. Dehydration can cause many symptoms, including decreased urine production, dry and sticky mouth, sleepiness, dizziness, headache, thirst, and confusion. In some cases, dehydration can become a medical emergency. If you have diarrhea or any of these symptoms while taking this medication, let your doctor know.

Hand-foot syndrome: Hand-foot syndrome (Palmar-plantar erythrodysesthesia syndrome) is a side effect of some cancer treatments, including tucatinib. This side effect causes painful redness, blisters, and swelling on the palms of the hands and soles of the feet. If you experience these symptoms, tell your doctor as soon as possible.

Kidney function: Tucatinib should not be used by people with severely decreased kidney function.

Liver function: Decreased liver function or liver disease may cause this medication to build up in the body, causing side effects. If you have liver problems, 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.

Tucatinib can cause liver damage and decreased 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.

Pregnancy: There is no information about the safety and effectiveness of using tucatinib while pregnant. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if tucatinib passes into breast milk. If you are breast-feeding and are 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.

What other drugs could interact with this medication?

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

  • alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
  • aliskiren
  • antiarrhythmic medications (e.g., amiodarone, disopyramide, dronedarone, lidocaine, quinidine)
  • anticancer medications (e.g., docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, venetoclax, vincristine)
  • anticoagulants (e.g., apixaban, edoxaban, dabigatran, rivaroxaban)
  • antipsychotics (e.g., aripiprazole, clozapine, lurasidone, pimozide, quetiapine, risperidone)
  • apalutamide
  • aprepitant
  • azole antifungals (e.g., itraconazole, ketoconazole, voriconazole)
  • benzodiazepines (e.g., alprazolam, clonazepam, diazepam, lorazepam, midazolam)
  • bictegravir
  • bilastine
  • bosentan
  • bromocriptine
  • buspirone
  • calcitriol
  • calcium channel blockers (e.g., amlodipine, diltiazem, felodipine, verapamil)
  • cannabis
  • clarithromycin
  • clopidogrel
  • colchicine
  • corticosteroids (e.g., beclomethasone, budesonide, cortisone, dexamethasone, fluticasone)
  • conivaptan
  • cyclosporine
  • darifenacin
  • digoxin
  • domperidone
  • dutasteride
  • elagolix
  • eliglustat
  • enzalutamide
  • eplerenone
  • ergot alkaloids
  • estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
  • eszopiclone
  • everolimus
  • fesoterodine
  • fexofenadine
  • galantamine
  • gemfibrozil
  • glecaprevir and pibrentasvir
  • guanfacine
  • HIV protease inhibitors (e.g., atazanavir, darunavir, saquinavir)
  • ivabradine
  • lomitapide
  • lumacaftor and ivacaftor
  • macitentan
  • maraviroc
  • mefloquine
  • mifepristone
  • mirtazapine
  • nadolol
  • naloxegol
  • narcotic pain relievers (e.g., codeine, fentanyl, methadone, morphine, oxycodone)
  • nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
  • oxybutynin
  • phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
  • pimecrolimus
  • praziquantel
  • progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
  • other protein kinase inhibitors (e.g., axitinib, bosutinib, dabrafenib, imatinib, nilotinib, pazopanib)
  • quinine
  • repaglinide
  • rifampin
  • riociguat
  • romidepsin
  • rupatadine
  • salmeterol
  • saxagliptin
  • seizure medications (e.g., carbamazepine. phenobarbital, phenytoin, primidone)
  • sirolimus
  • solifenacin
  • "statin" cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
  • tacrolimus
  • ticagrelor
  • tolterodine
  • tolvaptan
  • trazodone
  • "triptan" migraine medications (e.g., almotriptan, eletriptan)
  • vilazodone
  • zolpidem
  • zopiclone

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.

All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: