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Part 4 – PM4B Ali > Metallotherapeutics > Flashcards

Metallotherapeutics Flashcards

1
Q

How does cisplatin enter the cell?

A

(1) Prodrug, converted in vivo
(2) Encounters much lower chloride concentration inside the cell
(3) Removes chloride groups from cisplatin molecule + replaces with water
(4) Reacts with DNA each time it loses a chlorine

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2
Q

What is the target of cisplatin?

A

DNA

Nitrogen-7 on the adenine/ guanine

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3
Q

How does cisplatin affect the DNA?

A

Binds to nitrogen-7 on adenine/ guanine

Forms a covalent bond + displaces the water on the cisplatin

Intrastrand cross-links
- either on same strand/ opposite strands

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4
Q

Why is nitrogen-7 in adenine and guanine able to react so easily?

A

Lone pair of electrons

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5
Q

What is intrastrand linking?

A

Bridging 2 bases within the same strand

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6
Q

What is interstrand linking?

A

Bridging 2 bases on multiple DNA strands

More damaging to DNA

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7
Q

What types of toxicity is cisplatin associated with?

A
  • haemotologic toxicity
  • ototoxicity
  • nephrotoxicity
  • neurotoxicity
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8
Q

What is an example of off-target binding of cisplatin?

A

Ribonuclease A

Causes many side effects

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9
Q

Why is there a need for new platinum drugs?

A

(1) Cisplatin can have severe side effects
(2) Activity is required against a wider range of cancer types
(3) Cancer cells become resistant to cisplatin after repeated treatment

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10
Q

What is carboplatin?

A

2nd generation platinum anticancer drug

Less toxic than cisplatin

Chelate rings opens when reacting with water/ chloride ions

Reduced rate of reaction

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11
Q

What is nedaplatin?

A

New generation platinum anticancer drugs

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12
Q

How are nedaplatin, carboplatin, and cisplatin administered?

A

IV injection

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13
Q

What is oxaliplatin?

A

3rd generation platinum anticancer drug

Usually an IV infusion

Less toxicity

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14
Q

How is oxaliplatin usually administered?

A

IV infusion

with 5-fluorouracil and leucovorin (5-FU/LV)

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15
Q

What is satraplatin?

A

Can be given orally, only platinum anticancer drug currently able to do this

Prodrug
- removal of acetate groups in vivo give active form

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16
Q

What is the mechanism of action of platinum anticancer drugs?

A

Crosslinks DNA

17
Q

What are some benefits of oxaliplatin use, over cisplatin?

A

Reduced ototoxicity + nephrotoxicity

18
Q

What is the basis of photodynamic therapy?

A

Control of activation of the drug using light

To only activate drug in cells/ tissues of a very specific area

Can be used to localise treatment to reduce side-effects

19
Q

How can photodynamic therapy drugs be administered?

A
  • Topically
  • IV
  • PO
20
Q

How long after drug administration is light used to activate the drug, in photodynamic therapy?

A

2-3 days later

21
Q

What is a side effect of photodynamic therapy?

A

Damages the cells exposed to the laser light

22
Q

What is important when designing a drug that can be used in photodynamic therapy?

A

(1) Compounds needs to strongly absorb light
- e.g. tetrapyrrole (porphyrins)

(2) Needs to absorb deep-red to near infrared (NIR) light
(3) Needs to cause damage/ generate something that can cause damage when light is absorbed

23
Q

What is tetrapyrrole?

A

Basic building block of porphyrins?

Compound that strongly absorbs light
- often used in photodynamic therapy

24
Q

Why is deep-red to near-infrared (NIR) light useful in photodynamic therapy?

A

Penetrates furthest through tissue

25
Q

What is the significance of alternating single and double bonds in photodynamic therapy?

A

Very good for absorbing light

26
Q

What is current photodynamic therapy used to convert in cells?

A

Oxygen to singlet oxygen, from cellular oxygen

Singlet oxygen is an ultra-reactive species

27
Q

What is Photofrin?

A

Branded porfimer sodium

Used for palliative treatment of oesophageal cancers

Selectively accumulates in cancerous tissue

28
Q

Describe the structure of Photofrin.

A

Polymer chain of porphyrin units (up to 6)

29
Q

What is a benefit of Photofrin over anticancer platinum-containing compounds?

A

Does not cause kidney damage

nephrotoxicity

30
Q

What is Purlytin?

A

2nd generation photodynamic therapy compound

Tin atom at centre of porphyrin

Monomer

31
Q

What is a PDT compound?

A

Photodynamic Therapy drug

Used 2-3 days before being activated by light

Part 4 – PM4B Ali (19 decks)

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