Panitumumab is used for the treatment of colorectal cancer. It is a type of cancer that begins in the large intestine. The colon is the final part of the digestive tract. This condition typically affects older adults though it can happen at any age. Colorectal cancer usually begins as small and noncancerous clumps of cells called polyps that form on the inside of the colon. Polyps may be small and produce few symptoms. Colorectal cancer is a combined term of colon and rectal cancer that begins in the rectum. Signs and symptoms may include:

• Rectal bleeding or blood in your stool
• A persistent change in your bowel habits (diarrhea/constipation or a change in the consistency of your stool)
• A feeling that your bowel doesn’t empty completely
• Persistent abdominal discomforts such as cramps, gas, or pain
• Weakness or fatigue
• Unexplained weight loss

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll like vary, depending on the cancer’s size and location in your large intestine. In general, this type of cancer begins when healthy cells in the colon develop changes in their DNA. A cell’s DNA contains a set of instructions that tell a cell what to do.

Panitumumab is in the class of drugs known as a humanized monoclonal antibody. This is a targeted therapy that targets and binds to the epidermal growth factor receptors (EFGR) on the surface of the cell. This blocks an important pathway that promotes cell division. This results in the inhibition of cell growth and apoptosis. Panitumumab comes as a sterile and colorless liquid for intravenous infusion. This is available in the dosage forms of 5 mL, 10 mL, and 20 mL. The Food and Drug Administration (FDA) has already approved this medication.  

How does Panitumumab work?

Several cancer cells have structures called epidermal growth factor receptors (EGFRs) on their surfaces. These receptors allow a protein called epidermal growth factor (EGF) to attach to the cells. When the epidermal growth factor attaches to the receptor, this stimulates the growth and multiplication of the cancer cells. Panitumumab works by specifically recognizing, binding to, and blocking the EGFRs on cancer cells. This stops the cancer cells from receiving the messages they need to grow, multiply and spread. This also causes cancer cells to die.

Your doctor may do different tests to check the level of EGFR on your cancer cells, as this can predict if your cancer is likely to respond to the treatment. The response to treatment with Panitumumab has also been shown to be dependent on the presence of a non-mutated form of the RAS oncogene in the cancer cells.

How to use Panitumumab?

The dosage will depend on your medical condition, age, weight, and response to the treatment. Your doctor may start at a low dose and gradually increase it. You must take this medication exactly as it is prescribed. Do not take more or less than it is given by your doctor.

Panitumumab is to be given by injection into a vein. This is usually given once every two weeks. The recommended infusion time is about 60 minutes. It may be increased to 90 minutes if higher amounts of Panitumumab are administered. Before using this product, check it visually for particles or discoloration. If either is present, do not use the liquid. Clean the injection site with rubbing alcohol before injecting each dose. Learn how to store and discard medical supplies safely. To get the most benefit from it, use the medication regularly. Remember to take the prescription at the same time and in the same way each day. Let your doctor know if your condition does not improve or if it gets worse.

If you missed a dose, take it as soon as you remember it. If it is almost time for your next dose, skip the missed dose and follow your regular schedule. Do not double the dose to make up for the missed dose

What are the side effects of Panitumumab?

Common side effects:

• Diarrhea
• Vomiting
• Skin dryness
• Loss of appetite
• Tired feeling or weakness
• Blisters or ulcers in your mouth
• Trouble swallowing
• Low potassium (increased urination, extreme thirst, and muscle weakness)
• Nausea
• Tiredness
• Stomach or abdominal pain
• Constipation
• Growth of eyelashes
• Skin reactions such as acne, redness, itching, or rash

Call your doctor at once if you have:

• Sudden chest pain or discomfort
• Feeling short of breath
• Vision changes, redness, swelling, or irritation of your eyes/eyelids
• Swelling in your face
• Severe or ongoing diarrhea
• Signs of a kidney problem (painful or difficult urination, feeling tired or short of breath)
• Dehydration symptoms (being unable to urinate, feeling very thirsty or hot, and heavy sweating)
• Skin problems (skin itching, peeling, or cracking, severe or worsening acne, swelling or infection around your fingernails or toenails)

Get emergency medical help if you have these signs of an allergic reaction:

• Difficulty or trouble breathing
• Hives
• Swelling of your lips, face, tongue, or throat

Warnings and Precautions

• During this treatment, you will need to have a blood test to monitor the level of magnesium and calcium in your blood every two weeks.
• This should be used with caution in people with a low salt diet and those with liver or decreased kidney or liver function.
• This medication should not be used by pregnant, planning to become pregnant, or breastfeeding women.
• You should not share this or any of your prescriptions with others even if they have the same symptoms as yours.
• Without the consent of your doctor, you should not receive any vaccination or immunization.
• Let your doctor know about the drugs you take including vitamins, prescription medicine, and herbal supplements.
• Tell your doctor if you are allergic to it. This drug may contain an inactive ingredient that causes an allergic reaction.
• This drug should not be used in people with thickening and stiffening of the lungs and with inflammation of the lungs.
• While having this medication, avoid sun exposure. Always wear protective clothing when going outside.