Anti-Cancer Agents: Part 1 Flashcards
What are the 2 categories of major anti-neoplastic drugs?
- Cell cycle specific
2. Cell cycle nonspecific
Antimetabolites, taxanes, vinca alkaloids, epipodophyllotoxins, and antitumor antibiotics are examples of what?
Cell Cycle- Specific Anti-Neoplastic Drugs (Target cell & Give it in appropriate phase)
Aklyating agenst, anthracyclines, platinum analogs, camptothecins, and antitumor antibiotics are examples of what?
Cell Cycle NonSpecific (doesn’t matter when given)
What are some drugs that are S-Phase Specific?
Cyotsine, arabinoside, hydroxyurea (Anti-metabolites)
What are some drugs that are S-Phase Specific, but self limiting?
6-mercaptopurine and methotrexatre
What is the G2 phase also known as?
Pre-mitotic interval
What drugs are M-phase specific?
Vinca Alkaloids: Vincristine, Vinblastine, Paclitacel
What are some drugs that are phase-nonspecific?
Alkylating drugs, nitrosoureas, antitumor antibiotics, procarbazine, cis-platinum, dacerbazine
What is the principle of selective toxicity?
To destroy neoplastic cells via selective killing versus normal cells
What can selective toxicity be described in terms of?
Chemotherapeutic Index (CTI)
What is CTI?
Toxicity to CA cells (lethal dose)/Toxicity to normal cells
What is toxicity measured by?
LD50
What is LD50?
Lethal dose for 50% cell population
Do conventional cytotoxic drugs have a lot of success with selective toxicity?
No
What is a common AE of conventional cytotoxic drugs?
Myelosuppression
What can Low WBC counts (leukopenia) contribute to?
INFECTION Fever Sore throat Cough or shortness of breath Nasal congestion Burning during urination Shaking chills Redness, swelling and warmth at the site of an injury
What can low RBC counts (anemia) cause?
Fatigue Irritability Dizziness Shortness of breath Headaches An increase in heart rate/breathing
What can you give to a patient to help speed up the recovery of reduced WBCs?
G-CSF or GM-CSF
What is Nadir in terms of WBC and when does it occur?
The lowest WBC after chemo- occurs 7-14 days post-therapy
-Chemo for brain tumors can have a delayed nadir
What is the life span of a WBC and what is the implication of this?
Few hours-days… these have to be made new more often so the chemo effects on WBC are more pronounced
What is the lifespan of a RBC?
120 days
What is a major AE of conventional cytotoxic drugs?
Thrombocytopenia and neutropenia
What can low platelet counts cause?
Bruise easily Bleed longer than usual after minor cuts or scrapes Have bleeding gums or nose bleeds Develop large bruises (echymyoses) and multiple small bruises (petechiae) Serious internal bleeding Hair loss (alopecia) Appetite loss Weight loss Impact on sexuality
What is the general threshold of platelet count where you would have to decrease dose of chemo drugs?
100,000
-Packaging often times will tell you what it is… usually drug is C/I if it is under 50,000
Which class of drugs resemble normal substrates such as purine/pyrimidine analogs?
Antimetabolites
What do antimetabolites do?
Inhibit DNA synthesis…they incorporate into DNA and fool it
What are 2 main issues with antimetabolites?
- BM cell replication is profoundly inhibited
2. GI toxicity
True or False: Antimetabolites are highly cell specific?
TRUE- S phase
What is the result of an antimetabolite incorporating into DNA?
It will go through transcription and translation and result in a non-functional protein
What does 5-fluorouracil inhibit?
dTMP synthesis by inhibiting thymidylate synthase
No dUMP –> dTMP for DNA to be made
What does methotrexate do?
Inhibits dihydrofolate reductase which makes THF from DHF
Why inhibiting the production of THF, what does methotrexate ultimately inhibit the production of?
Methylenetetrahydrofolate (MTHF)
What is MTHF?
This is a folate compound that is required to make dTMP from dUMP (along with enzyme thymidylate synthase which is inhibted by 5-fluorouracil)
What 2 steps involved in DNA synthesis does Hydroxyurea inhibit?
- UMP to dUMP (via ribonucleotide reductase)
- CTP to dCTP (via ribonucleotide reductase)
-Both of these will result in a lack of DNA synthesis
So generally, what is methotrexate?
A folic acid analogue which inhibits dihydrofolate reductase and decreases nucleic acid synthesis
Folic acid is required for what?
DNA synthesis
What binds strongly to DHFR to inhibit the formation of MTHF, which a folate required for dTMP synthesis?
Methotrexate
Cells in what phase of the cell cycle are most sensitive to methotrexate?
S phase
What are 2 taxanes?
- Paclitaxel
2. Docetaxel
What is a risk with both taxanes?
Hypersensitivity