Classification: Antifolate Antineoplastic Agent
Pemetrexed works by blocking three separate enzymes that cells need to replicate. These enzymes, needed for folate-dependent metabolic processes, are required for DNA replication. Therefore, inhibiting these enzymes inhibits cellular growth.
How to Take Pemetrexed
Pemetrexed is given by intravenous (IV) infusion. It is typically given once every 21 days. The dose is based on the patient’s height and weight. A steroid medication is often given before pemetrexed to decrease skin rash. Folic acid supplements should be given for at least 5 out of 7 days prior to the first dose of pemetrexed, throughout treatment and for three weeks after the last dose is given. An injection of vitamin B12 should be given before the first dose of pemetrexed, and then about every 9 weeks during treatment. These vitamin supplementations will decrease the side effects you experience. Speak with your provider concerning the specific dosing of steroids, folic acid and B12 and timing of these medications.
Let your healthcare provider know all medications, vitamins and supplements you are taking as some can interfere with pemetrexed. Be sure to notify your care provider if you take any form of NSAID (non-steroidal anti-inflammatory drug) such as aspirin or ibuprofen because, taken in conjunction with pemetrexed, can cause kidney problems.
Possible Side Effects of Pemetrexed
There are a number of things you can do to manage the side effects of pemetrexed. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:
Low White Blood Cell Count (Leukopenia or Neutropenia)
White blood cells (WBC) are important for fighting infection. While receiving treatment, your WBC count can drop, putting you at a higher risk of getting an infection. You should let your doctor or nurse know right away if you have a fever (temperature greater than 100.4), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal.
Tips to preventing infection:
Low Red Blood Cell Count (Anemia)
Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the red cell count is low, you may feel tired or weak. You should let your doctor or nurse know if you experience any shortness of breath, difficulty breathing or pain in your chest. If the count gets too low, you may receive a blood transfusion.
Low Platelet Count (Thrombocytopenia)
Platelets help your blood clot, so when the count is low you are at a higher risk of bleeding. Let your doctor or nurse know if you have any excess bruising or bleeding, including nose bleeds, bleeding gums or blood in your urine or stool. If the platelet count becomes too low, you may receive a transfusion of platelets.
Nausea and/or Vomiting
Talk to your doctor or nurse so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try antacids, (e.g. milk of magnesia, calcium tablets such as Tums), saltines, or ginger ale to lessen symptoms.
Call your doctor or nurse if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.
Decrease in Appetite
Nutrition is an important part of your care. Cancer treatment can affect your appetite and, in some cases, the side effects of treatment can make eating difficult. Ask your nurse about nutritional counseling services at your treatment center to help with food choices.
Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.
Your oncology team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole grain breads, cereals and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include: applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. Drink 8-10 glasses on non-alcoholic, un-caffeinated fluid a day to prevent dehydration.
Mouth Ulcers (Sores)
Certain cancer treatments can cause sores or soreness in your mouth and/or throat. Notify your doctor or nurse if your mouth, tongue, inside of your cheek or throat becomes white, ulcerated or painful. Performing regular mouth care can help prevent or manage mouth sores. If mouth sores become painful, your doctor or nurse can recommend a pain reliever.
These include dryness, itching, and rash. You should use a moisturizer on your skin and lips, but avoid moisturizers with perfumes or scents. Your doctor or nurse can recommend medication if itching is bothersome. If your skin does crack or bleed, be sure to keep the area clean to avoid infection. Rash related to this medication typically occurs between doses and resolves before the next dose. A rash can result in blistering or peeling of the skin. Notify your oncology team if you develop a rash.
Other Side Effects
Some less common side effects that have been reported include: shortness of breath, blood clots, and an allergic reaction to the medication. Report any side effects to your healthcare provider.
Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. A woman should stop breastfeeding while on this medication because it is unknown if the medication can be passed through breast milk.
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