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30.03 Antimetabolites

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Overview

  1. Antimetabolites are a type of chemotherapy medication to treat cancer.
  2. They work in the S phase of the cell cycle
  3. Chemotherapy precautions must be taken
    1. Administration considerations
    2. Chemo certified nurses
  4. Agents include:
    1. Cytarabine
    2. 5-FU
    3. Methotrexate

Nursing Points

General

  1. Antimetabolites destroy cancer cells by blocking enzymes needed for DNA creation and work in the S phase of cell division.
  2. They work in cells that in this the S phase often- rapidly dividing 
    1. Most effective on fast-growing tumors 

Assessment

  1. Side effects → rapidly dividing cells susceptible to destruction also
    1. Bone marrow suppression
      1. Pancytopenia → low white blood cells, platelets, and low hemoglobin
      2. Risk of infection, bleeding, and anemia
    2. GI toxicities
      1. Nausea and vomiting
      2. Diarrhea
      3. Mucositis/ ulcers
    3. Organ-specific
      1. Hand-foot syndrome → damage to tissue on hands and feet
        1. With Capecitabine
      2. Cerebellar toxicities
        1. With Cytarabine

Therapeutic Management

  1. Used to treat MANY cancers and often as part of a combination of different therapies 
    1. Some examples →Leukemias, breast cancer, ovarian cancer, and intestinal cancers

Nursing Concepts

  1. Cellular regulation
    1. Disrupts cell duplication by changing the DNA and releasing free radicals
  2. Lab Values
    1. WBC normal 5-10 x10-3/mL
    2. HGB normal 12-17 g/dL (depending on gender)
    3. Platelets normal 150-400 x10-3/mL
  3. Patient Education

Patient Education

  1. Infection prevention
    1. Neutropenic precautions
    2. Hand hygiene
    3. Food preparation
    4. Avoid large crowds
  2. Bleeding precautions
    1. Shaving with an electric razor
    2. Fall prevention
    3. Oral care
  3. Managing side effects
    1. Nausea
    2. Diarrhea
  4. Chemo-specific considerations
    1. Skin changes

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Video Transcript

All right. Hi guys. Today, we’re talking about antimetabolites, which is a classification of chemotherapy, multiple medications fall under this category. So we’re going to kind of talk in broad terms about anti-metabolites. So I did just mention antimetabolites are a type of chemotherapy, so we need to adhere to chemo precautions. There’s a lot of considerations when we’re administering chemotherapy. I encourage you to check out the antineoplastic lecture to learn more about chemo precautions, but specific to antimetabolites. I need to mention that they are cell cycle specific, and we’re going to talk more about that on the next slide, but just to review what the cell cycle is: one cell goes into the cell cycle, right? It goes through several steps and two cells come out and chemo basically stops the cell cycle at some point, for antimetabolites that’s within the S phase of the cell cycle. 

And some of the medications you’ll hear are cytarabine or 5FU or Flurouracil is the other name for that, but you’ll pretty much only hear it called 5FU. And then methotrexate is another one. And again, there are many others also. Okay. So let’s just talk a little bit more about how these work they’re really fascinating how these anti-metabolites work. So, as I said, they work within the S phase of the cell cycle, and that’s when our, our DNA is being duplicated, right? So they block enzymes in the DNA creation. And this is an example of how methotrexate blocks folic acid. So our body usually uses this folic acid within the DNA strand, but the goal would be for it to get confused when methotrexate is in the blood cells and it will use methotrexate in place of this folic acid. 

So instead of this, going into this spot right here, the methotrexate will go in and that essentially will block the folic acid from being where it’s supposed to be. And that creates DNA destruction, basically. So this only works within the S phase and that’s important because we need to make sure that the chemotherapy is within the bloodstream. This picture here is our, our veins and the methotrexate we’re talking about. Right. We want to make sure it’s in the bloodstream when the cell is in the cell cycle during the S phase. So it’s only going to work if it is present when we need that folic acid in the DNA creation. So because of that, it works best on fast growing tumors that are frequently within the cell cycle and administration timing is very important. So these medications are given frequently, like as frequently as every eight hours, IV infusions, every eight hours of chemotherapy, or even they’re given over like a 72 hour period or a 96 hour period. So I’m an inpatient oncology nurse. And I give these medications a lot. A lot of times these patients are admitted to get these chemos because they’re given so frequently. So an outpatient oncology center can’t give an infusion that needs to be done more than once a day. So they’ll have to be admitted to get these medications. 

Okay. And side effects are kind of generic for many different chemotherapies. Bone marrow suppression is a big one. You’ll also hear myelosuppression or pancytopenia. And what that’s referring to is to a decrease in white blood cell, decrease in platelets and decrease in red blood cells, which equates to a decrease in hemoglobin, right? So basically our blood counts are low because the bone marrow was fast growing. So these medications are also going to be targeting these other healthy, fast growing cells. And another fast growing cell is GI cells, right? So we have several GI toxicities. We have the nausea, vomiting, diarrhea that can occur. And then more specific to anti-metabolites is the mucositis Or ulcers mouth ulcers, it should say. So we do very meticulous mouth care with these patients- at least once a shift, we have them on my unit, rinse their mouth with sodium bicarb and sodium chloride. And that’s just try to try to treat or prevent these mouth sores and then organ specific side effects of anti-metabolites: certainmedications cause specific ones. So, one that I want to mention is hand foot syndrome, 

And that occurs with capcytabine. And that’s a rash that can occur, basically it is cell destructions on the palms and the soles of the feet, so that can be a dose limiting toxicity. So we have to stop giving that chemo if that occurs. And then cerebellar toxicity is a big one with cytarabine. So damage to that cerebellum, if you remember, the cerebellum has a lot to do with coordination. So we’ll see people kind of stumbling or not quite in control of their extremities, if they’re getting toxicity to the cerebellum. And again, that’s a dose limiting side effects. We’ll have to stop giving the medication if that gets severe. Okay. And what type of cancers do these treat? Well, they treat a ton of different cancers. I had to mention leukemias because I’m an inpatient oncology nurse on a bone marrow transplant unit. 

So I treat a lot of leukemias. I see these often, but they also treat breast and ovarian cancers and intestinal cancers and several other cancers. And I just want to mention, like I’ve said this before in many of the other lectures, but I need to mention here that we often give these in combination. Sometimes they’re given as single agents, but most often it’s given in combination. Socthey’re getting other chemotherapies at this same time.
Okay. In patient education, like with any chemotherapies, we need to educate our patients about preventing infections. So with that would be neutropenic precautions because they often have low white blood cells, right? So you need to talk to them about hand hygiene, preparing their food appropriately, avoiding large crowds, wearing their masks out in public. Bleeding precautions because they have the low platelets, right? So that would be shaving within electric razors, fall prevention, good oral care, and just recognizing signs of bleeding, managing side effects. 

Of course, the nausea, vomiting, diarrhea, and those mouth sores are big ones with anti-metabolites. Chemo, specific education. I’m talking more about that hand foot syndrome, or plantar-palmer syndrome and then also the cerebellar toxicity. So we just need to educate our patients about what to watch for, what are those dose limiting side effects?
Nursing concepts. So we’ll briefly review these. Cellular regulation is interrupted, right? So we’re trying to target that S phase of the cell cycle. Lab values. We talked about pancytopenia right, low white blood cells, low platelets and low blood cells can occur. And then patient education is huge with anyone getting chemotherapy.
Okay. So some key points with anti-metabolites: they are cell cycle specific. So they target the rapidly dividing cells. And timing is very important, we need to adhere to chemo precautions because this is a chemotherapy. Side effects, organ toxicities, especially the brain, right. We’re talking about cerebellar, right? And then the GI tract and then combination therapy. These chemos are often given with other chemotherapies and they can be single agents, but often you’ll see them combined with other therapies. All right. That’s all I have for you. We love you guys. Go out and be your best self today and as always happy nursing.

 

 

Module 0 – Pharmacology Course Introduction
Module 3 – Disease Specific Medications

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