Praletrexate is a specific anitmetabolite, called an antifolate, designed to accumulate in cancer cells. Antifolates mimic the structure of naturally occurring molecules involved in DNA synthesis. Cancer cells mistake antimetabolites for normal metabolites allowing the compound to stop or slow critical enzymes involved in DNA synthesis, which then triggers cell death.
How to Take Pralatrexate
Pralatrexate is given by intravenous (IV) infusion over 3-5 minutes, once a week for 6 weeks in a 7 week cycle. The dose is based on the patient’s height and weight.
Pralatrexate interferes with certain vitamins in the body, so patients receiving this therapy must supplement these vitamins to reduce the risk of serious side effects. Patients will need to take folic acid daily (1-1.25 milligrams per day), beginning 10 days before pralatrexate, during treatment, and for 30 days after the last dose. In addition, patients will need to receive an injection of vitamin B12 (1mg), in their doctor’s office, no earlier than 10 weeks prior to starting therapy with pralatrexate, and every 8-10 weeks thereafter. Subsequent B12 injections can be given the same day as pralatrexate.
Certain medications can affect the way pralatrexate works. These include Bactrim (silfamethoxazole trimethoprim), probenecid and NSAIDS (non-steroidal anti-inflammatory drugs, including ibuprofen, aspirin, naprosen, Aleve, Motrin). Be sure to tell your oncology team about all the medications, vitamins and supplements you take.
Possible Side Effects of Pralatrexate
There are a number of things you can do to manage the side effects of pralatrexate. 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.
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.
Nausea and 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.
This medication can cause severe skin reactions including rash, sores, peeling and blistering of skin. Notify your oncology team if you develop any skin changes.
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.
There are several things you can do to prevent or relieve constipation. Include fiber in your diet (fruits and vegetables), drink 8-10 glasses of non-alcoholic fluids a day, and keep active. A stool softener once or twice a day may prevent constipation. If you do not have a bowel movement for 2-3 days, you should contact your healthcare team for suggestions to relieve the constipation.
This medication can cause liver toxicity, which your doctor may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown or pain in your abdomen, as these can be signs of liver toxicity.
Fever can be a side effect of pralatrexate, but it can also be an indication of infection. If you experience a fever (temperature above 100.4), you should notify your doctor right away.
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 your sperm is affected. You should consult with your healthcare team before breastfeeding while receiving this medication.
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