说明内容包括mode of action (作用方式)、side effects (副作用)、key points (要点)、way I remember (记忆方法)。
Okay, in this video, we're going to go over some important therapy agents that you should know.
So there are many chemotherapy medications out there, more than you could possibly ever remember. So I'm going to give you about six to remember that I think are most important.
So, the first one is an antitumor antibiotic. If you are following on with the card, I am on card 121 which starts the yellow screen section. So doxorubicin will be used for solid tumors. Its mode of action is to bind to DNA and inhibits DNA and RNA synthesis and causes death to rapidly dividing cells. So in terms of side effects, we’re going to have things such as GI upset, alopecia, bone marrow suppression which includes symptoms such as anemia, neutropenia, and thrombocytopenia and then cardiac toxicity is another side effect. And probably the most unique and one of the more important one wants to know is red discoloration of urine, sweat and tears. So in terms of key points, you definitely want to monitor the patient for signs of infection because of the risk of neutropenia. We also want to administer antiemetic for nausea and vomiting and they are going to want to monitor the patient's cardiac function due to the side effect of cardiac toxicity and then also monitor the CBC levels because we have bone marrow suppression. So the way I remember this is doxorubicin and I think of Ruby red and then Ruby red helps me to remember that it causes a red discoloration of tears and sweat and urine. It also reminds me the color red of the heart. So I know that we have cardiac toxicity and then it also reminds me the color of blood. So I know that we have bone marrow suppression. So we get anemia and neutropenia and thrombocytopenia. So it makes me think of the blood sweat and tears, it makes me think of a heart, and then it makes me remember that we are going to have some CBC problems due to bone marrow suppression. OK so that is doxorubicin.
Now let’s talk about an antimitotic medications which is vincristine. So vincristine can be used for a variety of tumors and cancers. I would not get hung up on exactly which cancers or tumors each of these medications can be used for. I mean you can if you want but that there's a lot of meds to learn. So that's not something I find that you would be tested on that much usually. So the mode of action of vincristine is to stop cell division during mitosis which is an M-phase specific medication. It does not cause bone marrow suppression, unlike the last medication we talked about. Side effect, the really important that you need one to know, is peripheral neuropathy and then other side effects can include phlebitis at the IV site, GI upset and as well as an alopecia, again. So key points, you are going to administer an antiemetics for nausea and vomiting. You can monitor for signs of neuropathy. So this would be pain like tingling, numbness, pins and needles type of pain and back pain and then you want to use a central line for infusion because of that risk of phlebitis. So it's very irritating unlike a powerful IVs. So you're going to use like a PICC line or a central line to give this medication. So the way I remember this medication is vin- is means wine in French. So too much wine or too much vin makes you not be able to feel your arms and legs. So that helps me remember the side effect of neuropathy like having a kind of numbness and tingling in your extremities when you use the vincristine, or drink too much wine, not that I’ve ever experienced that but I've heard that can be the case. OK so that's vincristine.
Now the next one I want to talk about is cyclophosphamide. It is used again for a variety of tumors and cancers. It inhibits protein synthesis by interfering with DNA and RNA synthesis. In terms of side effects of this medication, again we have bone marrow suppression. So this includes anemia, leukopenia, and thrombocytopenia. In addition, GI upset is common, alopecia is also common, and then a really unique one for this medication is hemorrhagic cystitis. And I would definitely remember that with cyclophosphamide. In terms of key points you want your patient to increase their fluid intake during therapy to like two to three litters per day, you need to monitor the blood for urine because of that side effect of hemorrhagic cystitis, and you're gonna want to monitor your patient’s CBC levels because we have the bone marrow suppression again, and then we are gonna also give an antiemetics for nausea and vomiting. So this one was tough. I tried to figure out a way to remember cyclophosphamide and I see that cyclo- in the beginning reminds me of cycling and you probably when you're on this medicine you probably don't want to go mountain cycling or mountain biking because A. you are going to be an anemic possibly so you have short of breath and fatigue because you have anemia, 2. you don't want to go because you have leukopenia, which increases your risk for infection. So if you’re in the mountains with all the dirt and trees and fresh you know, plants and such, that increases your risk of infection which is not good. And then 3, because you have thrombocytopenia, that means your platelets are really low, if you were to fall when you are on a mountain biking then you can bleed out because you don't have enough platelet. So that helps me to remember that cyclophosphamide is not a good medication be on and go cycling in the mountains. But also in addition to um you know, the anemia, leukopenia, thrombocytopenia, definitely remember hemorrhagic cystitis. OK.
And then we have got Leuprolide, which is a prostate cancer medication. It decreases levels of testosterone produced by the testes. Side effects can include hot flushes, gynecomastia, which is enlargement of breast tissue, bone loss, and decreased libido. Key points, you want the patient to increase their calcium and vitamin D intake because of that risk factor of decreased bone density and then also you're gonna want to monitor the patient’s PSA and testosterone levels throughout therapy. So again I’m stretching here as far as the way to remember so when i say leuprolide I think of Dr. Lu lie to me. He told me it would decrease my testosterone levels but now I've got all these horrible side effects, right? And then you as the nurse have to come up and explain why what that means, like that, yes, Dr. Lu told you that it would lower your testosterone but he didn't lie to you because lowering your testosterone is going to decrease your libido, cause hot flushes, and gynecomastia. So that just goes along with lower testosterone. So Dr. Lu did not lie to you. So that's Leuprolide.
OK Tamoxifen. Tamoxifen is a medication used for breast cancer. It competes with estrogen for binding sites in the breast and it stops the growth of estrogen-dependent cancer. Side effects include hot flushes, GI upset, hypercalcemia, and increased risk for endometrial cancer and then also increased risk for pulmonary embolism or PE. So the way I remember this is that Tami is a foxy lady. She has breast cancer but I still remember Tami being a foxy lady with breast cancer and again I am stretching here but if you have a good tip or suggestion, definitely leave it in the comments, because it might be better than mine in fact it probably will be better than mine for Tamoxifen.
OK, last one I want to go over is a biologic response modifier. So the one I would know here is interferon Alpha 2b. So you would use this for cancer well as some viral infections such as hepatitis, It’s mode of action is that interferons are basically proteins that increase a patient’s immune response to tumors and viruses. And it decreases cancer cell production, so kind of boost up the immune response in a patient. Side effects. There are a lot . So flu-like symptoms is probably the most important one we know here. So this includes fever, muscle aches, chills, and lethargy. Other side effects include bone marrow suppression, which is a pretty common side effect as you're seeing with all of these medications, cardio-toxicity, neural toxicity, alopecia, GI upset, and possible psychiatric disorders. So the way I remember this one is that interferon interferes with cancer and increases immune response and those all start with I, interferes, increases and immune response. So when I see interferon, I remember that it interferes with cancer and then I look at that I and I know that it increases immune response.
OK. So that is it for the chemotherapy section.
Questions 1. A 5-year-old male patient’s parents complain of recurring fever in their son over the course of a month. Past medical history is significant for easy bruisability. A CBC reveals a white blood cell count of 30,000 cells per microliter. A bone marrow biopsy confirms the diagnosis of acute lymphoblastic leukemia. This child is started on a chemotherapeutic regimen. Which of the following chemotherapy drugs acts by causing cross-links to form in DNA?
A. 5-Fluorouracil
B. Cyclophosphamide
C. Cytarabine
D. Methotrexate
E. Vincristine
2. A 54-year-old woman with a history of left-sided breast cancer has been in remission for 5 years following paclitaxel therapy coupled with surgical resection. She has now noticed a new lump in her left breast close to where the original tumor was excised. A biopsy reveals recurring cancer. After talking with her physician, she decided to undergo more chemotherapy. Her physician prescribes a drug, which inhibits DNA topoisomerase. Which chemotherapy agent inhibits topoisomerase?
A. Cisplatin
B. Docetaxel
C. Erlotinib
D. Irinotecan
E. Vincristine
Answers 1. B: Cyclophosphamide.
Cyclophosphamide is one of the drugs used to treat acute lymphoblastic leukemia. This drug is converted to an active metabolite that works by transferring alkyl groups to DNA strands, which then link to each other. Linked DNA strands cannot be replicated. When rapidly dividing cells (such as cancer cells) are unable to replicate this DNA, they undergo apoptosis. (A) 5-Fluorouracil (5-FU) is an antimetabolite that irreversibly inhibits the enzyme thymidylate synthase. Rapidly dividing cells exposed to 5-FU cannot synthesize thymidine and die. (C) Cytarabine is converted to an active metabolite that is incorporated into growing strands of DNA. Other nucleotides cannot be added to strand, and the cell is unable to remove the Cytarabine metabolite so DNA synthesis is halted. (D) Methotrexate is a folate antimetabolite. Folate is necessary for precursors to DNA synthesis, so inhibiting folate use by cells slows DNA synthesis and proliferation. (E) Vincristine interferes with microtubules, leading to cell cycle arrest in metaphase. 2. D: Irinotecan.
For patients with recurrent cancer, using a different chemotherapeutic agent than was used initially is often favored. This is because of the fact that cancer cells can become resistant to chemotherapy drugs to which they are exposed. In this patient’s case, paclitaxel (a microtubule inhibitor) was used during her initial treatment. The physician chose to use irinotecan, an agent that inhibits topoisomerase, this time in hopes to avoid any resistance the cancer cells may have to microtubule inhibitors. (A) Cisplatin is a DNA-binding agent that forms cross-links in DNA strands. It does not interfere with topoisomerase. (B) Docetaxel and paclitaxel are Taxanes that inhibit microtubule depolymerization. They do not interfere with topoisomerase. (C) Erlotinib inhibits cell proliferation by blocking the epidermal growth factor receptor. It does not interfere with topoisomerase. (E) Vincristine destabilizes microtubules, inhibiting normal cell cycle progression. It does not interfere with topoisomerase.
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