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

Temozolomide belongs to the group of cancer-fighting medications known as antineoplastics, and specifically to the group of antineoplastics known as alkylating agents. Temozolomide prevents the growth of cancer cells by interfering with the genetic material DNA, which is necessary for the reproduction of cells. Because cancer cells reproduce more quickly than normal cells, cancerous cells are targeted by the medication. Temozolomide is used to treat specific types of brain tumours.

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?

Act Temozolomide is no longer being manufactured for sale in Canada. For brands that may still be available, search under temozolomide. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The recommended dose of temozolomide varies according to body surface area, and takes into account whether you have been previously treated with chemotherapy. Before each new cycle of treatment, your blood will be tested and your dose of temozolomide may change depending on the test results.

Temozolomide is normally taken once a day for 5 days followed by a rest period of 23 days. This 28-day cycle is repeated until treatment is complete, as assessed by your doctor.

For a specific type of newly diagnosed brain tumour called glioblastoma multiforme, temozolomide is given daily along with radiation for 42 days. 4 weeks after radiation is complete, 6 cycles of 28 days of treatment with temozolomide are started.

Temozolomide capsules should be swallowed whole, with a full glass of water at least one hour before a meal. Do not open or chew the capsules. In case of accidental contact with the capsule contents, flush the area with water.

Antinausea medications can be taken just before or after temozolomide to help reduce the risk of vomiting. If vomiting occurs after taking the medication, do not take a second dose. Contact your doctor for further instructions.

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 miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, check with your doctor. Do not take a double dose to make up for a missed one, unless your doctor tells you to do so.

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

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 use this medication if you:

  • are allergic to temozolomide or any ingredients of this medication
  • are allergic to dacarbazine (DTIC)
  • have severely reduced bone marrow function

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
  • blurred vision
  • changes in taste perception
  • constipation
  • diarrhea
  • dizziness
  • drowsiness
  • fatigue
  • hair loss
  • headache
  • itching
  • joint pain
  • lack of energy
  • loss of appetite
  • muscle weakness
  • nausea
  • rash
  • tingling sensation
  • trouble sleeping
  • weakness
  • weight loss
  • vomiting

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:

  • anxiety
  • burning, prickling, or tingling sensations in the hands or feet
  • confusion
  • difficulty speaking
  • fever or chills
  • hearing impairment
  • increased blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
  • memory problems
  • mouth sores or inflammation
  • pain, bruising, irritation, itching, warmth, swelling, or redness at the injection site
  • rapid mood changes
  • rash with skin swelling, including on the palms of the hands and soles of the feet (if you are not having difficulty breathing)
  • shortness of breath and cough
  • signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
  • signs of bleeding (such as easy bruising, bleeding gums, nosebleeds, vomiting blood, blood in the urine, dark tarry stools)
  • signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
  • signs of infection (fever, chills, cough, sore throat)
  • 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)
  • pneumonia (symptoms such as cough that does not go away, or trouble breathing and fever)
  • tremor

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

  • seizures
  • signs of an allergic reaction (such as difficulty breathing, hives, or swelling of the face or throat)
  • signs of bleeding in the stomach (e.g., bloody, black, or tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)
  • 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
  • swelling of the hands or feet with shortness of breath
  • symptoms of herpes simplex encephalitis (e.g., fever, headache, personality changes, seizures, vomiting)

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 defects: Temozolomide can have genotoxic effects, meaning that it may damage the genetic material contained in sperm. This could lead to birth defects. If you are a man being treated with temozolomide, you should not father a child during treatment and for up to 6 months after treatment.

Blood disorders: This medication can cause the levels of certain blood cells to drop. This may lead to problems with blood clotting, the immune system, or the transport of oxygen through the body. Contact your doctor immediately if you develop a fever, chills, easy bruising, paleness, or bleeding (symptoms may include black and tarry stools, blood in the urine, or cuts that won't stop bleeding) while taking this medication. Your doctor will arrange periodic blood testing to monitor various blood components.

Hepatitis B infection: Temozolomide has been linked to reactivation of Hepatitis B infection. If you have had hepatitis B in the past 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.

Kidney function: The safety and effectiveness of using this medication have not been established for people with kidney problems. You should be closely monitored by your doctor if you have kidney problems.

Liver function: Temozolomide may reduce liver function and can cause liver failure, including death. 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. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

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.

Male infertility: Irreversible infertility may result from treatment with temozolomide. Therefore, men who may want to father a child in the future should seek advice on cryoconservation (freezing for long-term storage) of sperm prior to starting treatment.

Pneumocystis carinii pneumonia (PCP): People who take temozolomide daily along with radiation may be at a higher risk of developing a serious form of pneumonia called pneumocystis carinii pneumonia (PCP). If you are taking temozolomide daily along with radiation, your doctor may prescribe medication to help prevent PCP. Regardless of how you're taking temozolomide, your doctor will monitor you during your treatment for symptoms of PCP (e.g., cough that doesn’t go away, trouble breathing, fever).

Vomiting: Nausea and vomiting are very common with temozolomide treatment. Antinausea medications taken before or after taking temozolomide may be recommended.

Pregnancy: This medication may harm the baby if used during pregnancy. Women should avoid becoming pregnant while taking this medication. Use effective birth control while using this medication and for 6 months after stopping the medication. Tell your doctor immediately if you become pregnant.

Breast-feeding: It is not known if temozolomide passes into breast milk. It is recommended that women should stop breast-feeding while taking this medication.

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

Seniors: People over the age of 70 are more likely to experience a decrease in white blood cell counts or platelet cells. This can affect their body's ability to fight infection or their blood's ability to clot.

What other drugs could interact with this medication?

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

  • aminosalicylate drugs (e.g., mesalamine, olsalazine, sulfasalazine)
  • amphotericin B
  • anti-psychotics (e.g., clozapine, promazine)
  • baricitinib
  • cladribine
  • deferiprone
  • denosumab
  • leflunomide
  • mesalamine
  • natalizumab
  • nivolumab
  • olaparib
  • ofatumumab
  • ozanimod
  • pimecrolimus
  • ruxolitinib
  • sphingosine 1-phosphate receptor (S1P) receptor inhibitors (e.g., fingolimod, ponesimod, siponimod)
  • sulfasalazine
  • tacrolimus
  • tofacitinib
  • upadacitinib
  • vaccines
  • valproic acid

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.

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