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Chemotherapies - Cancer Drug List for FRCR CO1 > Anti-metabolites > Flashcards

Anti-metabolites Flashcards

1
Q

What are the anti-metabolites?

A
  • Capecitabine
  • 5-FU
  • Gemcitabine
  • Methotrexate
  • Pemetrexed
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2
Q

What is the mechanism of action of anti-metabolites?

A

Mimic normal cellular metabolites esential for nucleotide biosynthesis, use, or metabolism

Interferes with replication function

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3
Q

What is the mechanism of action of 5-FU and capecitabine?

A

Mimic pyramidine bases
Inhibits thymidylate synthetase and thymidine production

S Phase specific

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4
Q

How is capecitabine absorbed?

A

Rapid and extensive but incompletely
High bioavailability
Cmax 1.5 hours

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5
Q

How long does it take for capecitabine to reach a steady state?

A

14 days

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6
Q

What is the Distribution of capecitabine?

A

<60% plasma protein binding
35% to albumin

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7
Q

How is capecitabine metabolised?

A

Bioactivated and metabolised in the liver

FdUMP and DUTP active metabolites
also inactive metabolites

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8
Q

What enzyme increases activation of capecitabine to 5-FU enhanced in tumour cells?

A

Thymidine phosphorylase

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9
Q

How is Capecitabine eliminated?

A

Urine 95%

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10
Q

What is the half-life of capecitabine?

A

45 minutes

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11
Q

What are the indications for capecitabine?

A
  • Colorectal
  • Breast
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12
Q

What are the common AEs?

A
  • Mucositis
  • PE
  • Colitis
  • Cardiotoxicity
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13
Q

What is the Distribution of 5-DU?

A

10% plasma protein bound

Crosses BBB

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14
Q

How is 5-FU metabolised?

A

DPD in liver metabolises to FdUMP and inactive metabolites

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15
Q

How is 5-FU excreted?

A

60-80% repsiratory

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16
Q

What is the half-life of 5-FU?

A

20 min

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17
Q

What are the sife effects of 5-FU

A

Same as cape

More myelosupression - neutropenia + thrombocytopenia with bolus

More PPE with continuous infusion

18
Q

What drugs do Cape and 5-FU interact with?

A

Phenytoin
Warfarin
Thiazide diuretics

Cape - PPIs

19
Q

What is the mechanism of action of Gemcitabine?

A

S phase specific

Deoxycytidine analogue

Metabolised to active diphospahte and triphosphae nucleosides

These inhbit ribonucleotide reductase and get corporated into DNA

DNA synthesis ihibited and apoptosis induced

20
Q

What is the distribution of Gem?

A

Linear
Negligible PPB
Not extensively distributed into tissues

21
Q

How is Gemcitabine metabolised?

A

Intracellular metabolism to active metabolites

(Cytidine Deaminase) Deaminated in blood, liver, kidneys - active metabolite

Plasma - inactive metavolite

22
Q

How is Gem eliminated?

A

Urine 98%

23
Q

What is the half-life of gem?

A

If infusion <70 min 1.5 hours

If infusion >70 min 4-5 hours

24
Q

What are the indications for Gem?

A
  • Pancreas
  • NSCLC
  • TCC of bladder
25
Q

What are the toxicities associated with Gem?

A
  • **LFTs%%
  • Diarrhoea
  • N&V
  • Oedema
  • Myelosuppression
26
Q

What is the mechanism of action of Methotrexate?

A

Methotexate and active metabolites compete for folate binding site on dihydrofolate reductase

For DNA synthesis dihydrofolate reductase must reduce folic acid to tetrahydrogolic acid

Inhbits DNA, RNA, and protein syntehsis

S Phase

27
Q

What is the absorption of methorexate

A

60% bioavailability

PO peak serum levels 1-2h

IM peak serum levels 0.5-1h

28
Q

How is methotrexate distributed?

A

50% PPB

Stored in organs for prolonged period

Can cross placenta

29
Q

How is Methotrexate metabolised?

A

Low dose not much
High dose liver and intracellular

Active metabolites - polyglutamates

Inactive metabolites - 7 hydroxy methotrexate

30
Q

How is Methotrexate eliminated?

A

90% urine

31
Q

What is the half-life of methotrexate?

A

10-15 hours

32
Q

What are the adverse events of methotrexate?

A
  • LFTs
  • Pneumonitis
  • Myelosuppression
  • Mucositis
33
Q

What does methotrexate interact with?

A
  • Alcohol
  • Antibiotics including penicillin
  • Digoxin
  • Hepatotoxics
  • Tetracyclines
  • Nephrotoxics
  • NSAIDs
  • PPIs
  • Salicylates
34
Q

What is the mechanism of action of Pemetrexed?

A

Pyrrolopyrimidine antifolate

Inhbits Thymidylate synthase, dihydrofolate reductase, glycinamide ribonucleotide formyltransferase

Folate metabolism and inhbition of A,G (purine) and T synthesis

35
Q

What is the distribution of pemetrexed?

A

81% PPB
No accumulation over cycles

36
Q

How is pemetrexed metabolised?

A

Hardly at all

37
Q

How is pemetrexed eliminated?

A

90% urine

38
Q

What is the half-life of Pemetrexed?

A

3.5 hours

39
Q

What are the adverse effects of pemetrexed?

A
  • Rash
  • Poor appetite
  • Diarhhoea
  • N&V
  • LFTs
  • Myelosuppression
40
Q

What are the indications for pemetrexed?

A
  • Adenocarcinoma lung (maintainence)
  • Mesothelioma
41
Q

What can interact with Pemetrexed?

A
  • Nephrotoxins
  • NSAIDs

Increased toxicity

Chemotherapies - Cancer Drug List for FRCR CO1 (5 decks)

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