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Irinotecan

(eye-rin-oh-tee-kan)

Trade/other name(s): Camptosar, CPT-11, irinotecan hydrochloride

Why would this drug be used?

This drug is used to treat people with colon or rectal cancer. Your doctor may use it to treat other types of cancer.

How does this drug work?

Irinotecan is a chemotherapy drug made from a type of plant alkaloid known as a topoisomerase I inhibitor. It is thought to work by blocking the action of an enzyme in cells called topoisomerase I. Cells need this enzyme to keep their DNA in the proper shape when they are dividing into 2 cells. Blocking this enzyme leads to breaks in the DNA, which leads to cell death. Because cancer cells divide faster than normal cells, they are more likely than normal cells to be affected by irinotecan.

Before taking this medicine

Tell your doctor…

  • If you are allergic to any medicines, dyes, additives, or foods.
  • If you have ever had radiation therapy to the abdomen or pelvis, as this may put you at increased risk for lowered blood cell counts.
  • If you have ever had liver problems. This drug is cleared from the body mainly by the liver. Reduced liver function may result in more drug than expected staying in the body, which could lead to unwanted side effects. Your doctor may need to adjust your dose accordingly.
  • If you have inherited fructose intolerance. Irinotecan contains sorbitol.
  • If you have any other medical conditions such as kidney disease, heart disease, lung or breathing problems, diabetes, high blood pressure, gout, or infections. These conditions may require that your medicine dose, regimen, or timing be changed.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. This drug may cause problems with the fetus if taken at the time of conception or during pregnancy. Men and women who are taking this drug should use some kind of birth control during treatment. It is important to check with your doctor about what kinds of birth control can be used with this medicine. In pregnant women, treatment with this drug should be used only if the potential benefit to the mother outweighs the risk to the fetus.
  • If you are breast-feeding. While no studies have been done, this drug may pass into breast milk and affect the baby. Breast-feeding is not recommended during treatment with this drug.
  • If you think you might want to have children in the future. This drug may affect fertility. Talk with your doctor about the possible risk with this drug and the options that may preserve your ability to have children.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Irinotecan can interact with a number of drugs and supplements, which may either raise or lower the level of irinotecan in your blood. Tell your doctor if you are taking any of the following:

  • anti-depressant drugs nefazodone (Serzone), fluvoxamine (Luvox), fluoxetine (Prozac, Serafem)
  • antibiotics erythromycin, clarithromycin, and similar drugs
  • anti-fungal antibiotics such as ketoconazole and itraconazole
  • the anti-nausea drug aprepitant
  • certain blood pressure medicines such as diltiazem and verapamil
  • HIV drugs such as indinavir, ritonavir, amprenavir, fosamprenavir, nelfinavir, atazanavir, and others
  • anti-seizure drugs carbamazepine, phenobarbital, and phenytoin can make the body get rid of irinotecan faster
  • TB drugs rifampin and rifabutin
  • St. John's wort (an herbal dietary supplement)

Don't start or stop taking any drugs while you are on irinotecan without talking with your doctor first.

This drug can cause serious diarrhea. Try to avoid laxatives and stool softeners while taking this drug.

There may be more drugs that interact with irinotecan. Check with your doctor, nurse, or pharmacist about your other medicines, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

Grapefruit or grapefruit juice may also change the level of this drug in your blood. Check with your doctor, nurse, or pharmacist about whether these or other foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Irinotecan is given by an infusion into a vein (IV) over 90 minutes. It is usually given either once every 3 weeks, or weekly for 4 weeks followed by 2 weeks off. The dose will depend on a number of factors, including the treatment schedule, your body size, your age and general health, your blood counts, how well your liver is working, whether you have had radiation to your abdomen/pelvis, and whether you have any side effects such as diarrhea.

Precautions

One of the major side effects of this drug is diarrhea, which in some cases may be severe. This may start a few hours or a couple of days after the drug infusion. If left unchecked, it could lead to dehydration and serious chemical imbalances. Your doctor will prescribe medicine to help prevent or control this side effect. Make sure you get the medicine right away, so that you will have it at home when you need it. Take the medicine as prescribed as soon as you notice any loose stools. Be sure to let your doctor or nurse know if you are having diarrhea, especially if it lasts more than 24 hours, or if you get lightheaded, dizzy, or faint.

This drug may affect part of your nervous system that controls body secretions, leading to what is known as cholinergic syndrome. Symptoms can include runny nose, increased saliva, excess tears in the eyes, sweating, flushing, abdominal cramps, and diarrhea. Let your doctor or nurse know right away if you notice any of these symptoms, as there are medicines that can help control them.

You may have nausea and vomiting on the day you receive this drug or in the first few days after. Your doctor may give you medicine before your treatment to help prevent nausea and vomiting. Your doctor will likely prescribe anti-nausea medicines that you can take at home. Have these medicines on hand for when you need them. Call your doctor if you are unable to take fluids by mouth due to nausea and vomiting.

You may notice that you are dizzy and have trouble with your vision in the first 24 hours or so after you take this drug. Do not drive or operate machinery if you have this side effect.

This drug may cause sores in the mouth or on the lips, often within the first few weeks after starting treatment. This can cause mouth pain, bleeding, or even trouble eating. Your doctor or nurse can suggest ways to reduce this, such as changing the way you eat or how you brush your teeth. If needed, your doctor can prescribe medicine to help with the pain.

This drug may increase your risk of major blood clots in the veins of the legs or lungs, which can travel to other parts of the body such as the lungs or brain. Tell your doctor right away if you notice chest pain, shortness of breath, or swelling, pain, redness, or warmth in an arm or leg.

Your doctor will likely test your blood before and during your treatment, to check for effects of the drug on blood counts or on blood chemistry. Based on the test results, you may need medicines to help treat the effects. Your doctor may also need to reduce or delay your next dose of this drug, or even stop it altogether. Keep all your appointments for doctor visits and lab tests.

This drug can lower your white blood cell count, mainly in the weeks after the drug is given. This can increase your chance of getting an infection. Be sure to let your doctor or nurse know right away if you have any signs of infection, such as fever (100.5° or higher), chills, pain when passing urine, a new cough, or bringing up sputum.

This drug may lower your platelet count in the weeks after it is given, which can increase your risk of bleeding. Speak with your doctor before taking any drugs or supplements that might affect your body’s ability to stop bleeding, such as aspirin or aspirin-containing medicines, warfarin (Coumadin), or vitamin E. Tell your doctor right away if you have unusual bruising, or bleeding such as nosebleeds, bleeding gums when you brush your teeth, or black, tarry stools.

Tell your doctor or dentist that you are on this drug if you are planning to have surgery or any procedure.

Call your doctor if you have pain in your belly and you can't move your bowels, especially if you also have bloating and loss of appetite.

Rarely, people on this drug have serious lung problems, Tell your doctor right away if you have new or worsening cough, trouble breathing, and fever. Your doctor may need to stop your treatment to manage this problem.

Do not get any immunizations (vaccines) during or after treatment with this drug without your doctor's OK. This drug may affect your immune system, which can cause vaccines not to work, or even lead to serious infections. Try to avoid contact with people who have recently received a live virus vaccine, such as the oral polio vaccine or smallpox vaccine.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Common

  • diarrhea*
  • nausea/vomiting*
  • lowered white blood cell count with increased risk of infection*
  • hair thinning or loss, including face and body hair*
  • abdominal (belly) pain
  • loss of appetite
  • feeling weak

Less common

  • cholinergic syndrome (may include runny nose, increased saliva, sweating, tearing in the eyes, flushing, abdominal cramps, and diarrhea)*
  • sores in the mouth or on the lips*
  • constipation
  • fever and/or chills
  • feeling dizzy
  • skin rash
  • abnormal blood tests which suggest that the drug is affecting the liver (Your doctor will discuss the importance of this finding, if any.)

Rare

  • lowered blood platelet count with increased risk of bleeding*
  • major blood clots*
  • lowered red blood cell count (anemia)
  • shortness of breath
  • cough
  • feeling sleepy
  • allergic reaction with shortness of breath, itching, hives, swelling in the mouth or throat, or dizziness, which can happen with the first dose or later doses of this drug
  • death due to infection, bleeding, severe diarrhea, lung disease, or other problems

*See "Precautions" section for more detailed information.

There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 1996.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 12/17/2009
Last Revised: 12/17/2009