Obinutuzumab belongs to the group of cancer-fighting medications called antineoplastics. Specifically, it is a monoclonal antibody that belongs to the group of antineoplastics known as biological response modifiers. It is used with the medication chlorambucil to treat chronic lymphocytic leukemia (CLL) for adults who have not previously been treated for CLL. It is also used with other chemotherapy, to treat follicular lymphoma (FL).

CLL is a blood cancer that causes too many white blood cells to be produced and causes them to live too long. FL is a type of non-Hodgkin's lymphoma that causes too many of a specific type of white blood cell (B-lymphocytes) to be produced. Obinutuzumab works by attaching to these white blood cells, causing them to die.

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.

For treating Chronic Lymphocytic Leukemia (CLL), the recommended adult dose of obinutuzumab is 1000 mg, given by intravenous infusion (into a vein), into a site specially prepared for giving this medication. Obinutuzumab is given as a series of 6 cycles, each lasting 28 days.

For the first cycle, 100 mg of obinutuzumab is given on Day 1, and the remaining 900 mg is given on Day 2. A dose of 1000 mg is given on Days 8 and 15. For the remaining cycles, a dose of 1000 mg is given on Day 1 of each cycle only.

When treating Follicular Lymphoma (FL), the recommended dose of obinutuzumab is 1000 mg, given by intravenous infusion on Day 1, Day 8, and Day 15 of the first cycle. For the remaining 5 cycles, obinutuzumab is only given on Day 1 of each 28-day cycle. If the first 6 - 8 cycles of treatment are effective, obinutuzumab may be continued as 1000 mg every two months for up to two years.

Very careful handling of this medication is required, and it is always given in a hospital or similar setting with access to sterile equipment for preparation of the medication and facilities to treat medical emergencies, such as infusion reactions.

Many things can affect the 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.

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

Each vial of sterile, preservative free, non-pyrogenic, clear, colourless-to-slightly-brownish liquid contains 1000 mg of obinutuzumab. Nonmedicinal ingredients: L-histidine/L-histidine hydrochloride poloxamer 188, trehalose, and water for injection.

Do not take this medication if you are allergic to obinutuzumab 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 takes 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 taking 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
• hair loss
• headache
• nausea
• 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:

• fever
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of heart failure (e.g., shortness of breath; fatigue; swelling in legs, ankles, feet)
• signs of heart problems (e.g., fast, irregular heartbeat or pulse; chest pain; sudden weight gain; difficulty breathing; leg swelling)
• 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 progressive multifocal leukoencephalopathy (PML) (e.g., memory loss, vision loss, difficulty thinking or walking)
• symptoms of hepatitis B (e.g., mild fever, fatigue, loss of appetite, jaundice)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• 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 a heart attack (e.g., chest pain or pressure, pain extending through shoulder and arm, nausea and vomiting, sweating)
• symptoms of an infusion reaction (e.g., chest pain, flushing, shortness of breath, skin rash, sudden dizziness)
• symptoms of tumour lysis syndrome (e.g., producing less urine, cloudy urine, kidney problems, muscle spasms, nausea, shortness of breath)

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.

Birth control: This medication may cause infants to be born without B-cells if this medication is used by the mother during pregnancy. Women of childbearing age who are taking obinutuzumab should use an effective method of birth control such as condoms during treatment and for 18 months after stopping the medication.

Bleeding: Obinutuzumab may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.

Heart disease: Obinutuzumab may cause severe cardiovascular reactions, such as heart attack, irregular heartbeat, angina, or stroke. People who already have heart disease may find that this medication makes their symptoms of heart disease worse. If you have any form of heart 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.

Hepatitis B virus (HBV) reactivation: People who have had hepatitis B infections may find that this infection returns with the use of obinutuzumab. Obinutuzumab works by reducing the number of infection-fighting white blood cells. By doing so, the hepatitis B virus may be reactivated, causing liver damage.

Contact your doctor immediately if you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin.

Infection: Obinutuzumab is intended to reduce the number of B-cells, which are specific types of cells that fight infection in the body. This reduces your body's ability to fight infections. 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.

Infusion reactions: This medication can cause a hypersensitivity or infusion reaction. Symptoms of this type of reaction generally appear during the infusion of the medication and may include flushing, itchiness, hives, chest pain, shortness of breath, and a dramatic drop in blood pressure. These reactions can cause death if a health care provider is not informed immediately. If you experience any of these symptoms, or notice them happening to someone, let your nurse or doctor know immediately.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. 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.

Progressive multifocal leukoencephalopathy (PML): There have been reports of PML after using obinutuzumab. PML is a rare disorder that causes nerve damage in the brain. If you experience memory loss, vision loss, trouble thinking, or difficulty walking, contact your doctor immediately.

Tumour lysis syndrome: Obinutuzumab, like many other cancer medications, causes many cancer cells to be suddenly killed when treatment is first started. This can overwhelm the body with waste products from the cells. As a result, the body may not be able to keep up with getting rid of all the waste. When this happens, you may experience nausea, shortness of breath, or notice cloudy urine, joint pain or muscle spasms. This is called tumour lysis syndrome. Your doctor may prescribe some medications to help your body get rid of the waste products. Make sure you understand how to use these medications and report any of these signs or symptoms to your doctor immediately.

Vaccines: Vaccines (e.g., yellow fever, BCG, cholera, typhoid, varicella, meningococcal, diphtheria) should not be given while you are taking obinutuzumab. Vaccinations should be postponed until recovery from treatment with obinutuzumab is complete.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication may pass into breast milk. If you are breast-feeding and are receiving obinutuzumab, it may affect your baby. Because the potential for harm to an infant is not known, you should stop breast-feeding if you are receiving obinutuzumab.

Women who have used obinutuzumab in the past should not breast-feed for at least 18 months after stopping this medication.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: It is likely that people over the age of 75 will experience more side effects and more severe side effects. If you are over age 75, you should report any unusual effects to your doctor as soon as possible.

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

• acetylsalicylic acid (ASA)
• alfuzosin
• alpha-agonists (e.g., clonidine, methyldopa)
• amifostine
• amiodarone
• angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• anti-psychotics (e.g., clozapine, olanzapine, quetiapine, risperidone)
• apixaban
• barbiturates (e.g., butalbital, pentobarbital phenobarbital)
• BCG vaccine
• baricitinib
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• bortezomib
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• cladribine
• clopidogrel
• dabigatran
• deferiprone
• denosumab
• desmopressin
• diazoxide
• dipyridamole
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• echinacea
• edoxaban
• fingolimod
• heparin
• hydralazine
• leflunomide
• low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
• mesalamine
• natalizumab
• nitrates (isosorbide dinitrate, nitroglycerin)
• non-steroidal anti-inflammatory medications (NSAIDs; e.g., diclofenac, ibuprofen, naproxen)
• ocrelizumab
• olsalazine
• ozanimod
• pentoxifylline
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pimecrolimus
• ponesimod
• prasugrel
• quinine
• rivaroxaban
• sacubitril
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• serotonin/norepinephrine reuptake inhibitors (SNRIs; e.g., desvenlafaxine, duloxetine, venlafaxine)
• siponimod
• sulfasalazine
• tacrolimus
• ticagrelor
• tofacitinib
• upadacitinib
• vaccines
• warfarin

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