Irinox 40

Indications

Irinotecan is a cancer medicine used mainly for advanced or spread (metastatic) cancer of the colon or rectum, either with Fluorouracil and Folinic acid or on its own after other treatment. A special liposomal form is used for some advanced pancreatic cancers, and it is sometimes used for other solid tumours on specialist advice.

How It Works

Irinotecan blocks topoisomerase I, an enzyme cancer cells need to unwind and copy their DNA. With this enzyme blocked, the DNA breaks and the cancer cells die.

Dosage and Administration

Irinotecan is given in hospital by a doctor or nurse as a drip into a vein, usually over 30 to 90 minutes, in repeated cycles. The dose is based on body size, liver function, blood counts and the other medicines used, and is as prescribed by the cancer specialist. Medicines to prevent sickness and diarrhoea are usually given as well.

Interactions

• Rifampicin, Carbamazepine, Phenytoin, Phenobarbital and St John's wort can lower its effect and should be avoided.
• Ketoconazole and some HIV medicines such as Atazanavir can raise its levels and side effects.
• Other chemotherapy and radiotherapy add to its effect on the bone marrow.
• Live vaccines must be avoided during treatment.

Contraindications

• Chronic inflammatory bowel disease or bowel blockage.
• Severe bone marrow failure.
• High bilirubin (more than 3 times the upper normal limit) or severe liver problems.
• Pregnancy and breastfeeding.
• Allergy to irinotecan.

Side Effects

Common:

• Early reaction during or soon after the drip: sweating, stomach cramps, watery eyes, extra saliva and diarrhoea. An injection of Atropine is often given to treat or prevent it.
• Late diarrhoea, starting more than 24 hours after the dose, which can be severe. The team will explain how to take Loperamide and when to call.
• Low blood counts, raising the risk of infection, bleeding and anaemia.
• Nausea, vomiting, tiredness, loss of appetite and hair loss.

Get urgent medical help for diarrhoea that does not settle within 24 hours of starting treatment for it, any diarrhoea with fever, a temperature of 38°C or more, dizziness or very little urine (dehydration), black stools, unusual bleeding, or breathlessness.

Pregnancy and Lactation

Irinotecan can harm an unborn baby and must not be used in pregnancy. Both women and men should use reliable contraception during treatment and for the period the doctor advises afterwards. Do not breastfeed during treatment.

Precautions and Warnings

• People with a gene variant called UGT1A1*28 break down irinotecan more slowly and may need a lower dose.
• Regular blood counts and liver tests are needed.
• Drink plenty of fluids when diarrhoea starts.
• It can cause dizziness and blurred vision for a day after the drip; take care with driving.

Overdose

Overdose is rare as it is given in hospital. Too much causes severe diarrhoea and very low blood counts and is managed by the hospital team with fluids, infection treatment and close monitoring.

Therapeutic Class

Antineoplastic (anticancer), topoisomerase I inhibitor.

Storage

Stored by the hospital or pharmacy as directed on the pack, usually below 25°C, away from light; do not freeze. Keep out of the reach of children.