The trade name of irinotecan is Camptosar. The other names of this drug are Camptothecin-11 and CPT-11. Irinotecan chemotherapy is used for treatment of colon cancer in the metastatic stage. This drug is classified as a plant alkaloid and topoisomerase I inhibitor. It is used in treating colon cancer in combination with other chemotherapy agents like 5-fluorouracil, leucovorin, and irinotecan. This treatment is called FOLFIRI chemotherapy.

Working of Irinotecan

Irinotecan is a topoisomerase 1inhibitor, which prevents DNA from unwinding. Podophyllotoxins and camptothecan analogs are topoisomerase inhibitors. Chemically speaking, it is a semi synthetic analogue of the natural alkaloid called camptothecin. Camptothecan analogs are derived from the tree called Camptotheca acuminata. The plant alkaloids are cell-cycle specific i.e. they attack the cancer cells during specific phases of division.

Topoisomerase inhibitors like irinotecan interfere with the action of topoisomerase enzymes (topoisomerase I and II) that manage the structure of DNA required for replication.

Topotecan is also a Camptothecan analog and a topoisomerase I inhibitor.

Administration of Irinotecan

• This drug is given intravenously. There is no pill form of this drug. It is an irritant drug which means it damages the tissue if leaked out of the vein while infusing. Hence, it should be administered by highly skilled professionals. In case of chemotherapy spills, contact your nurse or your health care provider immediately.
• An irritants cause inflammation of the vein through which it is given along with tissue damage. You should notify your doctor if you notice redness, inflammation or pain at the IV site.
• The amount and frequency of this drug depends on various factors like, the height, weight and overall health of the patient. It also depends on the type and stage of the cancer.

Side Effects of Irinotecan Chemotherapy

Like any other chemotherapy drug, irinotecan has its set of side effects. Some of these are-

• Early diarrhea that occurs during infusion or within 24 hours of infusion along with symptoms like runny nose, increased salivation, watery eyes, sweating, flushing and abdominal cramping.
• Late diarrhea that occurs after 24 hours post infusion and persists for 10-15 days. You need to manage the diet with the help of your doctor and keep yourself hydrated in either of the cases of diarrhea.
• Nausea and vomiting. The doctors usually prescribe some antiemetics for chemotherapy to control this side effects.
• Weakness
• Low white blood cell count that hampers your immunity
• Low red blood cell count that causes anemia
• Hair loss
• Loss of appetite
• Fever
• Weight loss

Some relatively uncommon side effects of Irinotecan are-

• Constipation
• Shortness of breath
• Insomnia
• Cough
• Headache
• Dehydration
• Chills
• Skin rash
• Flatulence
• Flushing or redness of face during infusion
• Mouth sores
• Heartburn
• Swelling of feet and ankles

Precautions for Irinotecan Chemotherapy

• Make sure you inform your doctor about any medications and therapies you are taking or have taken in the past. This includes everything from prescribed medicines to herbs, OTC medicines, supplements, alternative therapies, etc.
• Do not take aspirin, products containing aspirin without consulting your doctor.
• Do not receive vaccinations with live vaccines without your doctor’s permission.
• Avoid consuming laxatives or stool stimulants as diarrhea is a common side effect of this drug which would only get worse because of laxatives
• Inform your doctor if you are pregnant, plan to conceive a child or a lactating mother as most chemotherapy drugs supposedly harm a developing fetus.
• Do not breast feed while taking irinotecan as it could enter the breast milk and harm the baby.

Irinotecan chemotherapy has been used as a second line of treatment where other drugs like oxaliplatin have failed in treating metastatic colorectal cancer. This therapy can be done in an outpatient setting and is tolerated well by most of the patients.