2.5 Purine & Pyrimidine Analogs

Question 1

What are the 5 different classes of chemotherapy?

Answer 1

• Alkylating agents
• Antimetabolites
• Topoisomerase inhbitors
• Mitotic inhibitors
• Anti tumour antibiotics

Question 2

Name two purine analogs

Answer 2

• Mercaptopurine
• Cladribine

Question 3

Name two pyrimidine analogs

Answer 3

Fuorouricil
Cytarabine

Question 4

What is the mode of action of purine analogs and pyrimidine analogs

Answer 4

The basic mechanism of action of both purine and pyrimidine analogues are similar.

They are incorporated into the cells DNA and act through the inhibition of DNA duplication, transcription and repair resulting in cell death (apoptosis)

Question 5

What is a commonly prescribed pyrimidine analogue

Answer 5

Fluorouracil

Question 6

What is one of the benefits of fluorouracil?

Answer 6

It can be given as a continuous infusion over several days,

this allows cells in other phases of the cell cycle to enter the S phase, enhancing Fluorouracil cell-kill capacity.

Question 7

What is one of the disadvantages of fluourouracil?

Answer 7

Intestinal absorption of fluorouracil can be erratic, therefore it needs to be given IV

Question 8

Which Pyramidine Analog in often used to treat haematological malignancies?

Answer 8

Cytarabine

Question 9

For which haematological malignancy is Cytarabine the cornerstone of treatment?

Answer 9

Acute Myeloid Leukaemia

Question 10

Which other hematological malignancies is Cytarabine used to treat?

Answer 10

• acute lymphoblastic leukaemia (ALL)
• chronic myeloid leukaemia (CML) in blastic phase
• non-Hodgkin lymphoma (NHL).

Question 11

What is the mode of action of Cytarabine?

Answer 11

Cytarabine enters the cell,
- Where it converts to its activated triphosphate form, Ara-CTP.

• Cytarabine is then incorporated into the cells DNA and
• Acts through the inhibition of DNA duplication, transcription and repair, resulting in cell death (apoptosis).
• For that reason, cytarabine is most effective when cells are undergoing rapid DNA synthesis
• during S phase of the cell cycle.