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PA1: Pharmacology > Week 2 Antibiotics: DNA + Protein Synthesis ✅ > Flashcards

Week 2 Antibiotics: DNA + Protein Synthesis ✅ Flashcards

1
Q

What are the 4 targets for DNA antibiotics?

A

DNA base synthesis
DNA strand breaking
DNA supercoiling
RNA polymerase

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2
Q

Which group of antibiotics work on DNA base synthesis?

A

Sulfonamides

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3
Q

Which antibiotics work on DNA strand breaking?

A

Metronidazole

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4
Q

Which group of antibiotics work on DNA supercoiling?

A

Quinolones

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5
Q

Which group of antibiotics work on RNA polymerase?

A

Rifampicin

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6
Q

Which are the 2 most important Sulfonomides to remember?

A

Trimethoprim and Nitrofurantoin

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7
Q

How does Trimethoprim work?

A

Inhibits dihydrofolate reductase

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8
Q

What kind of bacteria is Trimethoprim used for?

A

Broad spec (not Pseudomonas A)
Aerobic +ve staphylococcus, aerobic -ve E. coli, enterobacter, Klebsiella pneumoniae

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9
Q

What conditions can Trimethoprim be used for?

A

Uncomplicated UTIs e.g. cystitis

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10
Q

Why is Trimethoprim good for UTIs?

A

Excreted mainly unchanged

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11
Q

What are the adverse effects of Trimethoprim?

A

GI upset, rash, hyperkalaemia, haematological disorders

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12
Q

How does Nitrofurantoin work?

A

Damages RNA, DNA and proteins - free radical generated

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13
Q

Why is Nitrofurantoin good for resistance?

A

Multiple mechanism of action

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14
Q

What condition can Nitrofurantoin be used to treat?

A

UTIs - broad spec

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15
Q

Which UTI treating antibiotic is a pro drug?

A

Nitrofurantoin

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16
Q

Which drug is important to remember for DNA strand breaking?

A

Metronidazole

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17
Q

How does Metronidazole work?

A

Generates free radical which breaks down DNA

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18
Q

What type of bacteria does Metronidazole treat?

A

Anaerobic bacteria

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19
Q

What conditions can Metronidazole be used to treat?

A

GI tract infections, duodenal ulcers, C. diff

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20
Q

Which drug can be used to treat C Diff?

A

Metronidazole

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21
Q

Which antibiotic can cause C Diff?

A

Amoxicillin

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22
Q

Why is Metronidazole contraindicated with alcohol?

A

Metronidazole inhibits acetaldehyde dehydrogenase involved in alcohol metabolism

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23
Q

What symptoms can you get with alcohol and Metronidazole?

A

Flushing, headache, vomitting
Due to increase of acetaldehyde in body

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24
Q

Which important antibiotics are important to remember for inhibition of unwinding DNA supercoils?

A

Ciprofloxacin
Levofloxacin
Moxifloxacin

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25
Q

What are fluoroquinolones?

A

Active against -ve pseudomonas and anthrax

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26
Q

How do Fluoroquinolones work?

A

Helicase enzymes break H bonds in double helix

Gyrase and topoisomerase enzymes cut DNA strand during replication - INHIBITED

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27
Q

Why are Fluoroquinolones used as 2nd line antibiotics?

A

Resistance is easier

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28
Q

What bacteria are Fluoroquinolones used for?

A

Aerobic -ve

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29
Q

Which conditions are Fluoroquinolones used for?

A

UTI/severe GI

30
Q

What is the only oral antibiotic for Pseudomonas A

A

Fluoroquinolones (Ciprofloxacin)

31
Q

What is the important Fluoroquinolone antibiotic to remember?

A

Ciprofloxacin

32
Q

What are respiratory quinolones?

A

Active against strep. pneumoniae

33
Q

What are the 2 respiratory quinolones to remember?

A

Levofloxacin
Moxifloxacin

34
Q

What are the differences between Levofloxacin and Moxifloxacin?

A

They are both active against MRSA (Levofloxain less so)
Both have enhanced gram +ve activity - Strep pseudomonae

35
Q

What are the adverse effects of Fluoroquinolones?

A

Promote C Diff, colitis, nausea and diarrhoea
Increase arrhythmias (prolong QT interval)
Lower seizure threshold
Tendinitis -> rupture muscle tendons

36
Q

What are the interactions of Fluoroquinolones?

A

Drugs/conditions that prolong the QT interval
NSAIDS - increases seizures

37
Q

How are proteins made by bacteria?

A

RNA polymerase in nucleus

Transcription - makes mRNA from DNA using bases

mRNA goes to ribosome and binds

Ribosome reads mRNA and makes amino acid chain

tRNA carries amino acids to ribosome

mRNA read 3 bases at a time (codon)

Once finished, amino acids fold into 3D protein

38
Q

What is Rafampicin?

A

Inhibits RNA polymerase

39
Q

What is Rafampicin used to treat?

A

TB - 6-12m treatment as slow growing!
Also effective against leprosy

40
Q

What is adverse effect of Rafampicin?

A

Induces CYP enzymes which decrease effect of liver metabolised drugs

41
Q

What kind of bacteria is TB?

A

Mycobacteria

42
Q

What are the symptoms of TB?

A

Cough, haemoptysis, fever, night sweats, weight loss

43
Q

How does Isoniazid work?

A

Inhibits fatty acid synthase 2 (FAS-2) which polymerases fatty acids

44
Q

What are the adverse effects of Isoniazid?

A

Causes hepatitis, peripheral neuropathy, increase plasma concentration of anti-epileptic drugs

45
Q

How does Ethambutol work?

A

Inhibits arabinosyl transferase which prevents chains from attaching

46
Q

What are the adverse effects of Ethambutol?

A

Optic neuritis, haemorrhaging, blue-yellow abnormalities, loss of visual field

Reversible

47
Q

What is Pyrazinamide used for?

A

TB persisters - reduces treatment from 12m to 6m

48
Q

How do tetracyclines work?

A

Block tRNA binding

49
Q

What are examples of tetracyclines?

A

Aminoglycosides
Macrolides
Chloramphenicol
Doxycycline

50
Q

What is Doxycycline used to treat?

A

Acne vulgaris, COPD, pneumonia, chlamydia, malaria, anthrax, lyme disease

51
Q

What are the adverse effects of Doxycycline?

A

Nausea, vomitting, diarrhoea, oesophageal irritation/ulceration, photosensitivity

52
Q

What is adverse effect of Doxycycline?

A

Binds to calcium (teeth and bones) - avoid in children

53
Q

Which antibiotic is least likely to cause C diff/colitis?

A

Doxycycline

54
Q

How are aminoglycosides adminstered?

A

IV/IM, narrow therapeutic index

55
Q

How do aminoglycosides get into bacteria?

A

Water soluble so enter cells via O2-dependent pathway (absent in anaerobic bacteria)

56
Q

What is an example of aminoglycosides?

A

Gentamicin

57
Q

What is Gentamicin used for?

A

Severe sepsis, complicated UTI, endocarditis

58
Q

What other antibiotics does Gentamicin work well with?

A

Penicillins as they weaken the cell wall to enhance aminoglycoside uptake

59
Q

What bacteria is Gentamicin ineffective at treating?

A

Anaerobic

60
Q

What are the adverse effects of Gentamicin?

A

Ototoxicity (permanent - auditory hair cells)
Nephrotoxicity

61
Q

What bacteria can Chloramphenicol not be used to treat?

A

Pseudomonas

62
Q

What is an adverse effect of Chloramphenicol?

A

Suppresses bone marrow (panocytopenia)

63
Q

How is Chloramphenicol adminstered?

A

Topically e.g. eye ointment

64
Q

Can Chloramphenicol penetrate CNS? How?

A

Yes - lipid soluble

65
Q

How do Macrolides work?

A

Uptake by phagocytes to infection site

66
Q

What is an example of a Macrolide?

A

Erythromycin
Clarithromycin

67
Q

How do Macrolides work?

A

CYP3A4 inhibitor

68
Q

What bacteria can Erythromycin treat?

A

Broad spec gram +ve and some -ve (similar to Penicillin)

69
Q

What conditions can Erythromycin be used to treat?

A

Respiratory, skin and soft tissue infections

Penicillin allergies

H. Pylori and severe pneumonia (Legionaire’s)

70
Q

What is the adverse effects of macrolides?

A

Oral irritation, colitis, QT interval prolong, increases drugs that are metabolised by liverH

71
Q

How does Linezoid work?

A

Prevents tRNA initiating transcription

72
Q

Which is the last new antibiotic?

A

Linezoid

PA1: Pharmacology (8 decks)

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