Alkylating agents — Flashcards

Flashcard 1: What is the mechanism of resistance to Acyclovir/Famciclovir/Valacyclovir?_____

Answer: Mutated/Absent Thymidine Kinase

Flashcard 2: Which two alkylating agents must be activated by CYP450 in the liver?_____

Answer: Cyclophosphamide, Ifosfamide

Flashcard 3: Which alkylating agent is used to treat both hematologic malignancies (leukemia, lymphoma) and solid tumors?_____

Answer: Cyclophosphamide

Flashcard 4: What class of drugs does cyclophosphamide belong to?_____

Answer: Alkylating agents (cytotoxic chemo)

Flashcard 5: What is the mechanism of Chloramphenicol resistance?_____

Answer: Plasmid-encoded acetyltransferases that inactivate the drug

Flashcard 6: Mechanism and indication of Anastrozole?

Answer: Aromatase inhibitor used in postmenopausal breast cancer

Extra: Mechanism: Competitively inhibits aromatase, decreasing estrogen synthesis. Indication: ER-positive breast cancer in postmenopausal women. Examples of other aromatase inhibitors: Letrozole, Exemestane.

Flashcard 7: Mechanism of action of Exemestane:

Answer: Irreversible (Steroidal) Aromatase Inhibitor

Extra: Mechanism: Irreversible inhibition of the enzyme aromatase. Indication: Breast cancer in postmenopausal women. Note: Exemestane is a steroidal inhibitor, unlike Anastrozole and Letrozole which are non-steroidal (reversible).

Flashcard 8: alkylating agents

Answer: absence of digits (and multiple varied anomalies)

Flashcard 9: Teratogenic effect of folate antagonists?

Answer: Neural tube defects (NTDs)

Extra: Folate antagonists (e.g., Methotrexate, Aminopterin) interfere with DNA synthesis and are potent teratogens. Maternal use, especially during the first trimester (organogenesis), is strongly associated with neural tube defects. Low folate levels in general are a risk factor, which is why folic acid supplementation is recommended preconceptionally.

Flashcard 10: What is the mechanism of action of Methotrexate (MTX)?

Answer: Inhibits dihydrofolate reductase (DHFR)

Extra: Methotrexate is a folate analog that competitively inhibits DHFR, leading to a decrease in dTMP and DNA synthesis. In contrast, Trimethoprim inhibits bacterial DHFR and Pyrimethamine inhibits protozoal DHFR.