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Stage 4 Content > Antibiotics chemistry > Flashcards

Antibiotics chemistry Flashcards

1
Q

What is the MOA of macrolides

A
  • Macrolides are bacteriostatic
  • they bond close to p site on 50s ribosomal unit
  • this blocks the passage of peptide chain into the exit tunnel
  • means no amino acid can get in
  • therefore no proteins can be made
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2
Q

What is an example of a macrolide

A
  • Clarithromycin

- Erythromycin

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3
Q

What is the MOA of quinolones ad fluoroquinolone

A
  • they stabilise DNA gyrase enzyme intermediate by ‘base stacking’ via pi-pi bonds, which stops the enzyme from working
  • this stops the super coiling process after DNA gyrase has made the cut on the DNA
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4
Q

What is the role of DNA gyrase in bacteria

A
  • DNA gyrase is Topoisomerase II enzyme that uses ATP hydrolysis and Mg2+ ions to
  • super coil the bacteria DNA when it is not being used for replication
  • in the active site of DNA gyrase there are tyrosine residues which are important for cutting the DNA
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5
Q

Why do Quinolones and Fluoroquinolone have a good absorption

A

-they are zwitterionic so have a neutral charge

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6
Q

What is an example of Quinolones and Fluoroquinoloes

A
  • Ciprofloxacin

- Levofloxacin

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7
Q

What is the MOA of tetracycline

A
  • Tetracyclines have planar rings with O2 (strong lewis base)
  • the O2 allows it to bind to Mg2+ ions on the ribosome via metal chelation (Lewis acid- Lewis base bond)
  • When the tetracycline binds, it disrupts the function of the ribosome so tRNA cannot bind
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8
Q

What are some of the side effects of tetracyclines

A
  • if used in children below 12 years old it can cause yellowing of the teeth
  • it can also cause photosensitivity
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9
Q

What is a main drug-drug or drug-food interaction with tetracyclines

A

-it interacts with iron, diary and antacids

because it is a metal chelator

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10
Q

What is an example of a Tetracycline

A

-Doxycycline

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11
Q

What is an example of a glycopeptide

A

Vancomycin

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12
Q

What is the MOA of Vancomycin

A
  • Vancomycin caps the end of the cell wall so the bacteria cannot form the peptidoglycan cross link to strengthen its cell wall
  • this means the cell wall can burst due to osmotic pressure thus releasing the bacteria’s content
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13
Q

What is the bacteria resistance mechanism for Vancomycin

A
  • Bacteria switches D-alanine amino acid on the cell wall to lactic acid
  • this means vancomycin cannot bind and cap it so the bacteria can still make the peptidoglycan cross link
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14
Q

What is the MOA of Trimethoprim

A
  • it inhibits synthesis of essential metabolites via:
  • binds to dihydrofolate reductase as a competitive inhibitor of dihydrofolic acid
  • this mean dihydrofolic acid cannot be reduced to tetrahydrofolic acid
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15
Q

What is the MOA of Sulphanilamide

A
  • sulphanilamide are structural analogues of PABA

- they competitively inhibit dihydropteroate synthase so folic acid cannot be produced by the bacteria

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16
Q

What is the MOA of metronidazole

A
  • Metronidazole enters the cell via passive diffusion and is reduced to give radical species that are toxic to cells
  • it treats anaerobic activity e.g c.diff
17
Q

What is a unique side effect of Vancomycin

A

-Red man syndrome

18
Q

What is the MOA of 𝛃-lactam

A
  • All 𝛃-lactam have square structure which have a bond angle of 90 degrees
  • C=O normally likes to be at 120 degrees bond angle because it is sp2 hybridised but in 𝛃-lactam it is as 90 degrees
  • this makes it very easy to attack the 𝛃-lactam and cause it to open like a book
  • the 𝛃-lactam bond to serine on the transpeptidase enzyme causing the 𝛃-lactam to open up and get stuck in the transpeptidase enzyme
  • therefore peptide chain and water are blocked from entering the enzyme to be able to make the peptidoglycan cross links
  • this means the bacteria bursts due to osmotic pressure
19
Q

What is the MOA of gentamicin

A

It inhibits bacteria proteins synthesis by binding to the 30s unit of the Ribosome

20
Q

Which drugs require therapeutic drug monitoring

A
  • Gentamcin

- Vancomycin

21
Q

What is an example of a 𝛃-lactam

A
  • Penicillin

- Cephalsporin

22
Q

How does bacteria form their cell wall

A
  • they form it via a transpeptidation reaction using transpeptidase enzyme
23
Q

What is the bacteria resistance mechanism against 𝛃-lactam

A

-Bacteria can produce 𝛃-lactamase enzymes which open up the 𝛃-lactam ring before it is able to inhibit the cell wall

24
Q

What is the side effects of penicillin

A
  • anaphylaxis
  • rash
  • Steven-johnson’s syndrome

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