Episode 082: Pharmacology 101: Part 2 (REBOOT!)

As we prepare for another round oncology series in the weeks to come, we thought we would pause and go back to to the basics. We continue on our Pharmacology 101 series this week. This is such a high yield episode for anyone who cares for patients receiving therapy for their cancer!

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• Irritant vs. Vesicant:

  • Each drug is deemed one of these based on the degree of tissue damage that can result if drug extravasates under skin.

  • Vesicant: needs central access

  • Irritant: can be given peripherally

• Does my patient need a port/picc?

  • If vesicant, then usually get

  • If they need to do a continuous infusion for several days (e.g. 5-FU), they need a port

  • Some patients will request one because of difficult access

  • Advantages of ports:

    • Easy access for labs

    • Easy access for chemotherapy/fluids

  • Disadvantages:

    • Risk of infection

    • Risk of thrombosis

• General overview of chemotherapy side effects:

  • Going to target the fastest growing cells in the body, which includes cells that line the GI tract, skin, hair/nails, and blood cells

  • Therefore side effects are related:

    • GI: nausea/vomiting, diarrhea (sometimes constipation), decreased appetite, taste changes

    • Low blood counts

      • WBC nadir ~10-14 days (generally), and recover 21-28 days after chemo

• What about unique side effects of chemotherapy classes? How do we keep them straight?

  • We love keeping “Chemoman” from the USMLE study days in mind!

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• Anthracycline

  • MOA:Topoisomerase inhibitors

  • Ends in “rubicin”

  • You might hear people call doxorubicin the “red devil”

  • Used in lots of cancers

  • Hair loss occurs with this one

  • Known to cause cytopenias and associated with higher nausea potential 

  • Unique side effects:

    • Heart failure (always get baseline echo!)

    • Development of MDS and leukemia 

• Alkylating agents

  • MOA: Drugs add alkyl group to the guanine base of the DNA molecule, preventing linking of strands

  • End in “fosfamide”

  • Ifosfamide or cyclophosphamide (AKA cytoxan)

  • Used in lots of cancers

  • Known to cause cytopenias and hair loss

  • Unique side effects:

    1. Secondary MDS or leukemia possible 

    2. Ifosfamide = neurotoxicity = methylene blue antidote

    3. Cyclophosphamide = hemorrhagic cystitis due to acrolein byproduct accumulation = prevent by giving mesna to protect bladder

• Antimetabolites

  1. MOA: Purine analog, pyrimidine analog, folate antagonists; therefore prevent production of base pairs or binds instead of normal base pairs

  2. End in “abine” - capecitabine, cytarabine, gemcitabine, cladribine, fludarabine

  3. Also 5-FU and 6-MP in this category so “number followed by dash”

  4. Unique side effects:

     1. Think bone marrow suppression in this category  

• Platinum agents

  • MOA: Believed to cause cross-linking of DNA

  • End in “platin”

  • Associated with high risk of neuropathy 

  • Unique side effects:

    • Cisplatin:

      • Nephrotoxicity

      • Ototoxicity

      • High risk of nausea; need special prophylaxis 

    • Carboplatin: cytopenias

    • Oxaliplatin: higher rates GI side effects

• Microtubule agents

  • MOA: Impair microtubule function, therefore impacting cell division

  • End in “taxel” or vincristine/vinblastine (“V-stine”)

  • Unique side effects:

    • Neuropathy

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