Cladribine belongs to the group of cancer-fighting medications known as antineoplastics, and specifically to the group of antineoplastics known as antimetabolites. Cladribine is used to treat a type of blood cancer known as hairy cell leukemia. Cladribine fights cancer by preventing the growth of cancer cells, which eventually results in their destruction.

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.

The recommended dose of cladribine varies according to body weight. The medication is usually given at a dose of 0.09 mg per kg of body weight per day.

Many things can affect the schedule and 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. Very careful handling of this medication is required. It is always administered in a hospital or similar setting with access to sterile equipment for preparation.

Cladribine is given as an intravenous (into the vein) injection. The medication is usually injected through a specially prepared site on the skin and is given for 7 days by a continuous infusion. Very careful handling of this medication is required. It is always administered in a hospital or similar setting with access to sterile equipment for preparation.

Your doctor may want you to drink extra fluids while taking this medication in order to help you pass more fluid and protect your kidneys.

It is important this medication be given exactly as recommended by your doctor. If you miss an appointment to receive cladribine, contact your doctor as soon as possible to reschedule your appointment.

As well as interfering with the genetic material DNA of cancer cells, cladribine can interfere with some of your normal cells. This may cause a number of side effects such as unusual tiredness. Keep track of any side effects and report them to your doctor.

This medication is available as a 1 mg/mL injection.

Do not use cladribine if you are allergic to cladribine or any ingredients of the 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 uses 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 using 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.

• constipation
• diarrhea
• dizziness
• headache
• joint pain
• loss of appetite
• muscle pain
• nausea
• overall feeling of discomfort or illness
• sleeping problems
• unusual tiredness
• 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:

• numbness or tingling of the hands of feet
• pain, swelling, or redness at site of injection
• shortness of breath
• signs of bleeding (e.g., bloody nose, blood in urine, coughing blood, cuts that don't stop bleeding)
• skin rash
• stomach pain
• sweating, pale skin
• swelling of feet or lower legs
• unusually fast heartbeat

Contact your doctor immediately if any of the following side effects occur:

• fever or chills
• flu-like symptoms (e.g., cough, hoarseness, sore throat, fever or chills)
• difficulty moving arms or legs
• shortness of breath
• 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 infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• 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)
• signs of a skin reaction at the injection site (e.g., red streaks along vein where medication was injected, pain at injection site, redness, or warmth at site of injection)

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.

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.

Blood clotting: This medication can reduce the number of platelet cells in the blood. Platelets help the blood to clot, and a shortage could make you bleed more easily. Tell your doctor of any signs that your blood is not clotting as quickly. Such symptoms may include black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding.

Infection: As well as killing cancer cells, cladribine can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.

Kidney function: Cladribine may cause reduced kidney function. If you have reduced kidney function or kidney disease, 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.

Liver function: If you have reduced liver function or liver disease, 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.

Nerve damage: High doses of cladribine, and cladribine used with other treatments for cancer have been associated with damage to the nerves affecting the arms and legs. In some cases, permanent paralysis of the limbs has occurred. If you experience difficulty moving your arms or legs, or numbness and tingling in the limbs, inform your doctor immediately.

Red blood cells: Cladribine may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired or pale skin, contact your doctor as soon as possible.

Tumour lysis syndrome (TLS): In rare instances, cladribine may cause TLS, a potentially fatal condition that causes sudden kidney failure and abnormal heart rhythms. In the early stage of TLS, you may not have any symptoms, but your doctor will monitor for this condition with blood tests. If you experience symptoms of TLS (e.g., a pounding, fast, or irregular heartbeat; vomiting; fatigue or weakness; difficulty concentrating; swelling, numbness or tingling in hands, face, or feet; back pain; muscle cramps; fainting; or trouble breathing), contact your doctor immediately.

Pregnancy: Cladribine should not be used during pregnancy. There is a possibility of birth defects if either the man or woman is using cladribine at the time of conception, or if it is taken during pregnancy. Effective birth control should be practiced while using this medication and for at least 6 months after the last dose. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if cladribine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication for children have not been clearly established. It should only be prescribed or given by health care professionals familiar with the use of cancer chemotherapy in children.

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

• amphotericin B
• bacillus Calmette-Guérin (BCG)
• clozapine
• deferiprone
• denosumab
• echinacea
• fingolimod
• leflunomide
• natalizumab
• other cancer drugs
• pimecrolimus
• roflumilast
• tacrolimus
• tofacitinib
• vaccines

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 that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, 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.