Imatinib (Oral)

Imatinib, taken by mouth, is an anti-cancer medicine suggested for the treatment and prevention of the reproduction of cancer cells.

Overview

Imatinib is an anti-cancer drug or antineoplastic developed for the treatment of several types of cancers, including bone marrow syndromes.

Imatinib is most notable for shrinking and stopping the growth of chronic or accelerated cancer cells.

It is sometimes prescribed independently or in conjunction with other medications to destroy and deter the multiplication of cancer cells.

The medication is sold and marketed under the U.S. trade name Gleevec, which is available in either tablet or capsule form.

The body produces a type of protein known as KIT, which regulates the multiplication of cells throughout the body. When the body produces excess amounts of KIT, this subsequently results in the acceleration of cancer cell growth and ultimately the development of a tumor.

Imatinib zones in on specific proteins, including KIT, and helps to stop and prevent the development of new cancer cells. In some events, Imatinib has been noted for killing these cells.

Imatinib is beneficial for:

  • Reducing the size of current tumors in the body
  • Inhibiting the growth of existing or new tumors
  • Stopping new tumors from growing post-surgery

Imatinib may be prescribed for a prolonged period to help stop cancers from reoccurring, including after a surgical removal.

  • In a study completed by the brand Gleevec, 53% of patients taking this drug for up to one year after surgery did not exhibit signs of a reoccurrence. Three years later, more than 75% of all patients using the medicine post-surgery successfully benefited from no reoccurring symptoms.

Conditions Treated?

Type Of Medicine?

  • Antineoplastic (Cancer) Agent
  • Tyrosine Kinase Inhibitor

Side Effects

Anti-cancer drugs such as Imatinib may cause serious side effects. Your healthcare provider will complete a full assessment before prescribing this medicine to determine if the benefits outweigh the risks.

The most commonly reported adverse reactions of Imatinib include:

  • A bitter taste in the mouth
  • A burning sensation in the stomach
  • A headache
  • A loss of appetite
  • A numb or tingling sensation
  • An abnormal heartbeat
  • Bleeding from the nose
  • Bloody stools or urine
  • Bluish or purplish marks on the skin
  • Changes in the color of urine or stools
  • Changes in the sound of the voice or hoarseness
  • Changes in vision or trouble seeing
  • Congestion in the ear
  • Constipation
  • Convulsions
  • Coughing blood or coffee ground-like substances
  • Coughing up a pinkish mucus
  • Cuts that take a long time to clot or heal
  • Dehydration and/or dry mouth
  • Diarrhea or runny stools
  • Difficulty focusing
  • Edema or swelling of the hands and lower body area
  • Excess bleeding following a surgical procedure
  • Excess perspiration
  • Excessive belching
  • Extreme drowsiness
  • Eye redness
  • Eyes that water easily
  • Feeling anxious, nervous, or depressed
  • Feeling dizzy or lightheaded
  • Feeling irritable
  • Feeling itchy
  • Feeling sick all the time
  • Feeling weak
  • Fevers or chills
  • Flu-like symptoms, including a sore throat, coughs, congestion or sneezing
  • Gassiness
  • Glands that feel swollen
  • Gums that bleed easily, including when brushing or flossing
  • Heartburn or indigestion
  • Jaundice
  • Lesions on the skin
  • Lethargy
  • Loss of sight (temporary)
  • Low urine output
  • Mood swings
  • Nails or lips that appear bluish
  • Pain and tenderness in the abdomen
  • Pain in the back or side
  • Pain in the bones
  • Pain in the joints
  • Pain in the muscles
  • Pain or discomfort in the chest
  • Pain or tightness in the chest
  • Pain throughout the body
  • Painful menstruation with more blood loss
  • Rashes on the skin
  • Skin that blisters or peels
  • Skin that bruises easily
  • Skin that looks pale
  • Stiffness in the joints or muscles
  • Stomach cramps
  • Stunted growth in children
  • Sudden weight gain
  • Sweating at night
  • Trembling or shaking
  • Trouble breathing or swallowing
  • Trouble passing urine
  • Trouble talking or expressing oneself clearly
  • Ulcers in the mouth
  • Vomiting and feeling nauseous
  • Weight loss

When to call a doctor

If you suspect you have a severe adverse reaction to this medicine, do not hesitate to call 911. Some examples of medical emergencies include:

  • An allergic reaction: Accompanied by wheezing, trouble breathing, puffiness, and hives and/or welts.
  • A heart problem: Accompanied by an abnormal heartbeat, pain in the chest, weakness, and swelling.
  • Delayed growth: If you notice your child is exhibiting signs of delayed growth, such as a lower body weight or height, call your doctor.
  • New Infections: If you acquire a new infection, your body may be unable to adequately fight off viruses and bacteria. In these cases, medical intervention is required.
  • Liver problems: Accompanied by changes in stool or urine color, along with jaundice, sleepiness, nausea, tender stomach, and loss of appetite.

Dosage

The dose amounts for Imatinib vary from one patient to another and is based on:

  • The medication strength
  • The underlying condition
  • Division of daily doses
  • Intervals between daily doses
  • Timeline for treatment

The following tables provide an overview of average Imatinib doses based on the underlying condition being treated.

Do not start, stop, or alter your prescription without first consulting with your healthcare provider.

Imatinib Doses for ASM - Aggressive Systemic Mastocytosis

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 400 mg | 1X Daily

Imatinib Doses for CEL - Chronic Eosinophilic Leukemia

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 400 mg | 1X Daily

Imatinib Doses for HES - Hypereosinophilic Syndrome

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 400 mg | 1X Daily

Imatinib Doses for DFSP - Dermatofibrosarcoma Protuberans

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 800 mg | 1X Daily or 400 mg | 2X Daily

Imatinib Doses for GIST - Gastrointestinal Stromal Tumors

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 400 mg | 1X Daily (Max Daily Dose: 800 mg)

Imatinib Doses for MDS - Myelodysplastic Syndrome

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 400 mg | 1X Daily

Imatinib Doses for MPD - Myeloproliferative Diseases

  • Children: Varies Based on a Doctor's Evaluation
  • Adults: 400 mg | 1X Daily

Imatinib Doses for (Ph+ ALL) - Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia

  • Children: Varies Based On A Patient's Height or Weight (Max Daily Dose for Children 1 and Up: 600 mg)
  • Adults: 600 mg | 1X Daily

Imatinib Doses for (Ph+ CML) - Philadelphia Chromosome Positive Chronic Myeloid Leukemia

  • Children: Varies Based On A Patient's Height or Weight (Max Daily Dose for Children 1 and Up: 600 mg)
  • Adults: 400 mg | 1X Daily (Max Daily Dose: 800 mg)

Note: This dosage guide reflects the suggested preliminary amounts. The doctor may adjust the dose based on patients' tolerance and response to the treatment.

Imatinib is usually dispensed as either a 100 mg or 400 mg tablet or capsule. In most cases of treatment, 400 mg is prescribed daily for adult patients.

If the initial dose isn't causing the tumor to shrink, your healthcare provider may increase the dose to 800 mg per day.

Tips for taking oral Imatinib

To improve how this medicine works, follow these tips:

  • Take with Water: Taking Imatinib with a full glass of milk or water is recommended for preventing an upset stomach.
  • Swallow Whole: The tablet or capsule should be swallowed as-is, without crushing or breaking it. Patients who are unable to swallow pills should consult with a pharmacist to learn the next best course of action. Your pharmacologist may recommend dissolving the tablet in apple juice or water. However, there are specific dilution instructions available based on the medication strength. For example:

O Mix 100 mg tablets to 2oz (apple juice, water)

O Mix 400 mg tablets to 7oz (apple juice, water)

When diluting the pills or capsules, ensure the mix is fully dissolved and a homogeneous appearance is achieved by mixing it together thoroughly with a spoon. For best results, do not allow the mix to sit for long. Drink immediately.

Missed Doses

If you miss a dose of Imatinib, take it as soon as you remember. Nevertheless, do not double dose. If you have any concerns while taking this medicine, call your local pharmacy or healthcare provider for help.

Interactions

Patients who take Imatinib by mouth in conjunction with certain medicines, foods, or vaccinations may be exposed to negative interactions. Read more below for details on the demonstrated negative interactions with Imatinib:

Drug interactions

The concomitant use of oral Imatinib with the following drugs have been proven to increase the chances of adverse reactions:

  • Domperidone
  • Tolvaptan
  • Ibrutinib
  • Phenobarbital
  • Doxorubicin
  • Fentanyl
  • Lurasidone
  • Enzalutamide
  • Lumacaftor
  • St John's Wort
  • Cilostazol
  • Venetoclax
  • Olaparib
  • Doxorubicin Hydrochloride Liposome
  • Sonidegib
  • Bosutinib
  • Ketoconazole
  • Flibanserin
  • Fosaprepitant
  • Naloxegol
  • Warfarin
  • Ergotamine
  • Lomitapide
  • Gemfibrozil
  • Fosphenytoin
  • Phenytoin
  • Ivacaftor
  • Tacrolimus
  • Piperaquine
  • Simeprevir
  • Suvorexant
  • Ginseng
  • Carbamazepine
  • Idelalisib
  • Hydrocodone
  • Ifosfamide
  • Rifampin
  • Aprepitant
  • Ivabradine
  • Acetaminophen
  • Mitotane
  • Dihydroergotamine
  • Levothyroxine
  • Clozapine
  • Pimozide
  • Eplerenone
  • Eliglustat
  • Cobimetinib
  • Brexpiprazole

An adjusted dose is generally required when Imatinib is prescribed in conjunction with any of the medications on this list.

Food interactions

Medical researchers advise against eating or drinking raw grapefruits, grapefruit juices, or any byproducts of grapefruit when undergoing treatment with Imatinib.

The contents of this citrus have been proven to increase blood volume, which subsequently increases the risk of bleeding in patients taking Imatinib.

Vaccines

One of the side effects of using Imatinib is a weakened immune system. As a result, patients are advised to avoid getting any new vaccinations, including the:

  • Adenovirus shot
  • Live bacillus of Calmette and Guerin shot
  • Live cholera shot
  • Live influenza virus shot
  • Live measles virus shot
  • Mumps virus shot
  • Live poliovirus shot
  • Live rotavirus shot
  • Live rubella virus shot
  • Smallpox shot
  • Typhoid shot
  • Varicella virus shot
  • Yellow fever shot

Interactions with underlying medical conditions

Tell your doctor if you have any pre-existing medical conditions before commencing treatment with Imatinib. The antineoplastic agent could cause certain conditions to get worse.

As a precaution, peruse this list of medical problems that have been proven to interact negatively with Imatinib:

  • A hole in the stomach
  • A low white blood cell count
  • Abdominal fluid
  • An underactive thyroid
  • Anemia
  • Any new infections
  • Bleeding
  • Fluid or edema in any organ
  • Heart conditions
  • Kidney or liver disease
  • Low platelet count

OTCs

Do not use any new over-the-counter medicines before first confirming the safety of doing so with your medical provider. This includes non-prescription vitamins, supplements, or herbal products. St. John's Wort is also noteworthy for causing adverse reactions when it is used in combination with Imatinib.

Warnings

Read the warning label included with your prescription to learn common precautions while undergoing treatment with Imatinib.

History of allergies

Tell your doctor if you have a history of allergies to any medicines you have taken. In particular, you should note any past adverse reactions to foods, dyes, animal products, or preservatives.

Crushed or broken tablets

Imatinib features potent cancer-fighting ingredients. If you come into contact with a broken or crushed pill, wash your hands immediately and thoroughly with soap and running water.

Proper use

Imatinib is an effective drug for patients with certain cancer diagnoses. However, if it is used incorrectly, serious side effects may occur. As a result:

1. Take Imatinib exactly as prescribed
2. Do not take more than the outlined dose amount
3. Do not extend the treatment unless your doctor has advised you to do so
4. Do not discontinue the treatment without first consulting with your healthcare provider

Patients should be mindful that even slight adjustments in the dosage can throw the system off balance and cause significant negative side effects to occur.

Blood tests and follow-up visits

When using this medicine, plan for follow-up visits with your healthcare provider. Your doctor will monitor your progress and check:

  • If the medicine is improving the condition being treated
  • If any adverse side effects are developing or occurring

To help doctors better assess progress or drawbacks caused by Imatinib, blood and urine tests may be performed. Make every effort to keep all follow-up visits, including using a calendar to remind you when these are scheduled.

Skin irritations

One of the most common side effects of Imatinib is skin irritations. Consult your medical provider immediately if you experience the following signs of a severe skin allergy:

  • Cracked or peeling skin
  • Loose looking skin
  • Red marks on the skin
  • Acne-like rashes
  • Spikes in temperature
  • Blisters or abscesses on the skin

Risk of infections

Imatinib may compromise the immune system or the body's ability to fight off new infections. As a result, care should be taken to avoid others who may be sick as well as any person who has been recently immunized.

You should also check with your doctor before getting vaccinated. There is a greater risk of acquiring viruses if you receive a live vaccine.

As an extra layer of safety, patients taking Imatinib are advised to wear a protective face mask when visiting a hospital or clinic, or when encountering other household members who are sick.

Low blood and platelet count

Patients who take Imatinib may tentatively experience lower white blood cell or platelet counts. This dual effect increases the risk of bruising and bleeding as blood clotting processes are compromised.

If you bleed, the normal blood clotting processes may not work normally. This puts you at an increased chance of developing serious and potentially fatal health conditions associated with uncontrolled bleeding.

To lower this risk:

  • Avoid others who may be sick
  • Wash your hands thoroughly several times per day
  • Pay extra care when using knives or other sharp objects that are generally used in daily life, such as razor or nail cutter, for example.
  • Do not use your hands or fingers near your eyes or nose, as new infections can be easily transmitted this way.
  • Call your healthcare provider if you suspect a new infection.
  • Seek medical help right away if you have bruises on your skin; unusual bleeding, or any changes in stool color.
  • Do not play high-risk sports, such as football or boxing, for example. These increase the risk of sustaining an injury which may be difficult to treat. Additionally, contact sports increase patients' chances of bruising.

In some patients, unusual bleeding has been reported after brushing and flossing. As a result, patients may need to adjust their oral care regime to reduce the risk of bleeding.

Additionally, if you have any upcoming dental procedures, be sure to consult with your primary care provider.

Fluid retention and heart health issues

In some cases, Imatinib may result in heart health issues due to increased fluid retention. Some of the telltale signs of this condition include:

  • Pain or discomfort in the chest
  • Feeling excessively tired or weak
  • Trouble breathing
  • Abnormal heartbeat
  • Puffiness and inflammation, especially in the hands or feet

If these symptoms occur, consult your healthcare provider right away.

Liver disorders

People with a liver disease should not use Imatinib unless it is completely necessary. This drug may cause delays in waste removal processes and exacerbate or cause liver problems to occur. Some of the signs a liver issue are:

  • Urine color changes (dark yellow urine)
  • Feeling nauseous
  • Unexplained lethargy or drowsiness
  • Skin or eyes that appear yellow
  • Loss of appetite
  • Stomach that feels tender to the touch
  • Clay-colored stools

Risk of tumor lysis syndrome

Another risk associated with Imatinib is the development of tumor lysis syndrome, a serious and potentially fatal condition. To lower the risk, supplementary medicines are usually prescribed. Patients should be aware of the warning signs of tumor lysis syndrome, including:

  • Lower urinary output
  • Pain and stiffness in the joints
  • Pain and inflammation in the lower back or side
  • Abdominal pain
  • Sudden weight gain
  • Edema
  • Unexplained lethargy

If these symptoms occur, seek medical help right away.

Maintaining safety

Patients who use Imatinib may feel lightheaded, sleepy, or have sudden changes in vision. Extra precautions must be taken when performing high-risk activities, such as driving or operating heavy machinery.

For example, if you feel sleepy or faint when driving or using a machine, stop the activity and call for help. This warning should be applied to all activities that require you to be alert.

Senior patients

Senior patients taking Imatinib may be more susceptible to the side effects of the drug due to the presence of other preexisting conditions. In medical studies, senior patients using this medicine reported more incidences of sudden weight gain and swelling compared to younger patients taking Imatinib. Be sure to create a full list of all current conditions and provide it to your healthcare provider before commencing treatment with Imatinib.

Pregnant or nursing mothers

Imatinib is proven to cause harm to unborn babies. As a result, it is not recommended for use in expecting mothers. As an extra precaution, women who are taking Imatinib are generally prescribed birth control before and after treatment to prevent pregnancy. Post-treatment with a birth control generally lasts for two weeks.

Pediatric patients

Imatinib may be prescribed in pediatric groups with caution. In most cases, doses are based on patients' age and weight or overall size.

Pediatric patients undergoing treatment with Imatinib should moreover be carefully monitored and assessed for proper development. This medicine is known to stunt growth in children.

Storage

Place the medicine in an airtight container and avoid:

  • Heat
  • Freezing temperatures
  • Direct sunlight
  • Moisture

The prescription label generally instructs patients to keep the capsules in the original container and to store at a room temperature of 25°C (77°F).

After each use, be sure to reseal the cap tightly.

Do not place this medicine within the reach of children or pets. In the event of an accidental dosage, contact 911 immediately. The American Association of Poison Control Centers is also available by calling 1(800) 222-1222.

Avoid flushing the medicine down drain ways or in a toilet.

If your doctor discontinues treatment with Imatinib, discard any unused portions of this medicine by taking it back to a local pharmacy.

Summary

Imatinib is a prescription-only medication used to treat various forms of cancers, including aggressive tumors in the bone marrow.

In the United States, Imatinib is available under the brand name Gleevec. It is prescribed for both adult and pediatric patients for different types of cancers.

Patients are advised to follow all directions outlined on the prescription label to reduce the chances of an adverse reaction to the drug.

This medicine is not suggested for pregnant or nursing mothers as it is proven to cause harm to unborn babies and newborns. To mitigate this risk, women who take Imatinib are advised to use an effective form of birth control while undergoing treatment and for up to two weeks after stopping the drug in order to prevent pregnancy.

Some of the serious side effects of using Imatinib are heart failure, fluid retention, a severe skin reaction, liver issues, uncontrolled bleeding, kidney disorders, and tumor lysis syndrome. If these adverse reactions occur, seek medical help right away.

To reduce the side effects associated with this anticancer medicine, be sure to tell your doctor of any pre-existing conditions, current medications, and your full medical history. Based on this information, your healthcare provider can make an informed decision on which negative drug interactions to avoid, and in some cases, prescribe additional medicines to offset the risks.

While taking Imatinib, do not start taking any new medicines, including over the counter vitamins or herbal supplements before first speaking with your healthcare provider.

Imatinib is known to suppress the immune system. As a result, patients are advised to stay away from others who are ill and avoid any new vaccines until safety is established with a medical provider.

You should use caution when driving or operating heavy machinery, as dizziness and fainting are common side effects of Imatinib. To be safe, arrange for a designated driver to take you to and from work, school, and/or appointments during treatment with Imatinib.

Patients should take this medicine exactly as prescribed and at the suggested times listed. Any slight modifications in dosage have been shown to cause adverse reactions.

Imatinib is usually taken at the same time each day by mouth and with a full glass of water to reduce stomach irritations. Though the rule of thumb is to swallow this medicine whole, some patients who are unable to do so for medical reasons can dissolve the tablet in a measured amount of water or apple juice, then drink it right away.

Imatinib is labeled as a targeted therapy for effectively stopping the reproduction of cancer cells in the body. The response rates have been favorable, though there is no guarantee the medicine will work or stop the reoccurrence of former cancers.

If the preliminary dose proves unsuccessful, healthcare providers may increase the dose by up to a maximum of 800 mg per day for adults. Pediatric prescriptions vary based on the size of the patient.

Patients should also be aware that Imatinib may be given alone or concomitantly with other anti-cancer medicines for best results. Ultimately, a full doctor's assessment is needed to dispense a personalized treatment with Imatinib.