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Cell Wall Synthesis Inhibitors Flashcards

1
Q

What is the classification of Penicillin G?

A

penicillin
bactericidal
beta-lactam antibiotic

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2
Q

What is the mechanism of action of Penicillin G?

A

Cell wall synthesis inhibition - Inhibits transpeptidase enzyme which leads to the disruption of peptidoglycan (cell wall) synthesis, these defects in the cell wall leads to rupturing.

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3
Q

What is the spectrum of activity of Penicillin G?

A

narrow

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4
Q

What are the therapeutic indications of Penicillin G? (6)

A
  • G+ cocci - tonsillitis, Pneumococci
  • G- cocci – meningitis, gonorrhoea
  • G+ bacilli/rod - tetanus, gangrene
  • Bacteroides fragilis (oropharyngeal infections)
  • Treponema (syphilis)
  • Actinomyces (abscesses)
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5
Q

Why can Penicillin G not be administered orally?

A

It is acid labile (inactivated by gastric acid) which causes it to have a poor absorption in the GIT

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6
Q

How is Penicillin G administered?

A

intramuscular (IM) and intravenous (IV)

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7
Q

What % of Penicillin G is bound to plasma proteins?

A

50-60%

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8
Q

What is the T1/2 of Penicillin G and how does this affect excretion

A

Short (30 mins), so rapidly eliminated unchanged via kidneys

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9
Q

In which 3 ways can the effect of Penicillin G be prolonged?

A
  • Higher doses
  • Combined with probenecid
  • IM administration in depot form
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10
Q

What are 3 Disadvantages of Penicillin G?

A
  • Narrow spectrum of action
  • Acid-labile (so only parental administration)
  • beta-lactamase sensitive (inactivated by bacterial enzymes)
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11
Q

What are the 2 major adverse effects of Penicillin G?

A

Hypersensitivity reaction and Neurotoxic effects (convulsions)

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12
Q

What is the classification of Penicillin V

A

beta-lactam antibiotic

penicillin

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13
Q

What is the mechanism of action of Penicillin V?

A

Cell wall synthesis inhibition

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14
Q

What is the spectrum of activity of Penicillin V?

A

narrow

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15
Q

What are the therapeutic indications of Penicillin V?

A
  • less severe infections

- follow-up antibiotic after successful parenteral treatment of severe infections

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16
Q

How is Penicillin V administered?

A

orally (acid stable)

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17
Q

How is the % of Penicillin V oral-dose that is absorbed impaired?

A

impaired by food intake

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18
Q

What is the half-life of Penicillin V?

A

30min

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19
Q

What % of Penicillin V is bound to plasma proteins?

A

80%

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20
Q

Where is Penicillin V metabolised?

A

liver

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21
Q

By which organ is unchanged Penicillin V excreted?

A

kidneys

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22
Q

What are the adverse effects of Penicillin V?

A

Similar to Penicillin G

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23
Q

What is the classification of Cloxacillin/ Flucloxacillin?

A

beta-lactam antibiotic
Isoxazolyl penicillin
semisynthetic penicillin

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24
Q

What is the mechanism of action of Cloxacillin/ Flucloxacillin?

A

Cell wall synthesis inhibition

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25
Q

What are the therapeutic indications of Cloxacillin/ Flucloxacillin?

A

They are sensitive to beta-lactamase- resistant isolates of S aureus (normally resistant to Penicillin G)

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26
Q

How is Cloxacillin/ Flucloxacillin administered?

A

Orally (acid stable), otherwise IM and IV

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27
Q

How is the % of Cloxacillin/ Flucloxacillin oral-dose that is absorbed impaired?

A

impaired by food intake

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28
Q

What is the half-life of Cloxacillin/ Flucloxacillin?

A

30-60min

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29
Q

By which organ is Cloxacillin/ Flucloxacillin excreted?

A

kidneys

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30
Q

What are the adverse effects of Cloxacillin/ Flucloxacillin?

A

Similar to Penicillin G

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31
Q

What is the classification of Ampicillin?

A

beta-lactam antibiotic

aminopenicillin

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32
Q

What is the mechanism of action of Ampicillin?

A

Cell wall synthesis inhibition

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33
Q

What is the spectrum of activity of Ampicillin?

A

broad-spectrum of activity

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34
Q

What are the therapeutic indications of Ampicillin? (3)

A
  • gram-positive bacteria
  • gram-negative cocci
  • gram-negative bacilli : H. influenzae, Salmonella, Shigella, Proteus mirabilis and Entamoeba coli.
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35
Q

How is Ampicillin administered?

A

orally (acid stable), also parentally

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36
Q

How is the % of Ampicillin that is absorbed impaired?

A

impaired with food intake

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37
Q

What % Ampicillin is bound to plasma proteins?

A

17-20%

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38
Q

What is the half-life of Ampicillin?

A

80min

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39
Q

Where is Ampicillin eliminated?

A

in the gall and urine

40
Q

What are the adverse effects of Ampicillin?

A
  • weak oral absorption causes more damage to GIT microflora and diarrhoea
  • Others similar to penicillin G
41
Q

What is the classification of Amoxicillin?

A

beta-lactam antibiotic

aminopenicillin

42
Q

What is the mechanism of action of Amoxicillin?

A

Cell wall synthesis inhibition

43
Q

What is the spectrum of activity of Amoxicillin?

A

broad-spectrum of activity

44
Q

What are the therapeutic indications of Amoxicillin?

A

Similar to that of ampicillin

45
Q

How is Amoxicillin administered?

A

Oral (acid-stable), IV, IM very painful

46
Q

What % of Amoxicillin is absorbed in the GIT?

A

85% (not impaired by food intake)

47
Q

What is the half-life of Amoxicillin?

48
Q

What is the serum concentrations of Amoxicillin compares to Ampicillin?

A

2 1⁄2 times higher serum concentrations are reached

49
Q

How does the dosage of Amoxicillin compare to Ampicillin?

A

A lower dose than for Ampicillin can be administered

50
Q

Describe the distribution of Amoxicillin in the body fluids

A

A wide distribution in body fluids except for the cerebrospinal fluid

51
Q

What % of Amoxicillin is bound to plasma proteins?

52
Q

Where is Amoxicillin metabolised?

53
Q

By which organ is unchanged Amoxicillin excreted?

54
Q

What is Co-amoxiclav?

A

A combination of Amoxicillin and clavulanic acid

55
Q

What does Clavulanic acid do beta-lactamase?

A

inactivates it

56
Q

What is beta-lactamase?

A

An enzyme produced by bacteria that inactivate beta-lactam antibiotics (resistance)

57
Q

Why is clavulanic acid added to Amoxicillin?

A

it protects the antibiotic against inactivation

58
Q

What are the 4 adverse effects of Amoxicillin?

A
  • GIT disturbances, nausea and vomiting
  • Hepatitis, cholestatic jaundice from clavulanic acid
  • Excreted in breast milk
  • Others similar to Ampicillin
59
Q

What are the 4 Cephalosporins?

A
  • Cephazolin (first gen)
  • Cefuroxime (second gen)
  • Ceftriaxone (third gen)
  • Cefepime (fourth gen)
60
Q

What is the spectrum of activity of cephalosporins?

61
Q

What is the mechanism of action of cephalosporins?

A

Cell wall synthesis inhibition

62
Q

What is the classification of Cephalosporins?

A

Beta-lactam antiobiotics

semisynthetic antibiotics

63
Q

Which Cephalosporin is the most effective against gram-positive organisms?

A

First generation (Cephazolin)

64
Q

What is the consequence of a cephalosporin that is more effective against gram-negative organisms ?

A

they are less effective against gram-positive infections

65
Q

What is an advantageous property of cephalosporins?

A

They have a greater beta-lactamase stability (compared to penicillins)

66
Q

What type of bacteria is resistant to all cephalosporins?

A

enterococci

67
Q

What is the spectrum of activity of first gen cephalosporins? (2)

A

Streptococci, Staphylococcus aureus

68
Q

What is the spectrum of activity of second gen cephalosporins? (5)

A

E.coli, Klebsiella, Proteus, Haemophilus influenzae, Moraxella catarrhalis

69
Q

What is the spectrum of activity of third gen cephalosporins? (4)

A

Enterobacteriaceae, Neisseria gonorrhoeae, Staphylococcus aureus, Streptococcus pyogenes

70
Q

What is the spectrum of activity of fourth gen cephalosporins? (3)

A

As for 3rd gen, Is more resistant against beta-lactamases, aerobic gram-negative bacilli

71
Q

How are first gen cephalosporins administered?

72
Q

How are cephalosporins administered?

A

Parentally

73
Q

Are cephalosporins acid stable or acid labile?

A

Acid stable

74
Q

Describe the absorption of cephalosporins in the GIT?

A

poor absorption

75
Q

What is the half-life of cephalosporins?

76
Q

What are the 2 main excretion methods of cephalosporins?

A

glomerular filtration and tubular secretion.

77
Q

What are the adverse effects of cephalosporins?(3)

A
  • Hypersensitivity reactions
  • Intolerance to alcohol
  • Bleeding disorders
78
Q

What is the classification of Imipenem and Meropenem

A

Carbapenems

Beta-lactam antibiotics

79
Q

What is the mechanism of action of carbapenems?

A

Cell wall synthesis inhibition

80
Q

What is the spectrum of activity of carbapenems?

81
Q

What are the therapeutic indications of carbapenems? (4)

A

septicaemia, endocarditis, lower respiratory tract and genito- urinary tract infections

82
Q

Can imipenem be absorbed orally?

83
Q

How and where is imipenem metabolised?

A

Rapidly hydrolysed by dipeptidase in proximal renal tubule

84
Q

What inhibits dipeptidase?

A

Cilastatin

85
Q

What is formulated with imipenem and why?

A

Cilastatin, blocks renal metabolism and enhances its urinary concentration

86
Q

What are the adverse effects of carbapenems?

A

Similar to those of other beta-lactam antibiotics, include hypersensitivity and GIT effects.

87
Q

What is the classification of vancomycin?

A

glycopeptide antibiotic

bactericidal

88
Q

What is the mechanism of action of vancomycin?

A

Cell wall synthesis inhibition

89
Q

How does vancomycin inhibit cell wall synthesis?

A

Binds to peptidoglycan penta-peptide, this inhibits transglycosylation and prevents cross-linking of the peptidoglycan latticework, leads to rupturing of cell wall

90
Q

What are the therapeutic indications of vancomycin? (3)

A
  • Life-threatening infections
  • G+ infections caused by methicillin-resistant, beta-lactamase producing staphylococci and enterococci
  • Bowel inflammation (pseudomembranous colitis): Caused by Clostridium difficile (after antibiotic tx)
91
Q

How is vancomycin administered?

A

IV (not absorbed after oral intake and IM administration is painful)

92
Q

What is the half-life of vancomycin?

A

4 to 11 hours

93
Q

How is vancomycin excreted?

A

unchanged in the urine by glomerular filtration

94
Q

What are the adverse effects of vancomycin? (2)

A
  • Fever and rash

- Rapid administration causes histamine release which leads to hypotension and flushing (“red-neck/red-man” syndrome)

95
Q

What are the contraindications of vancomycin? (2)

A
  • People with auditory abnormalities, causes ototoxicity

- Geriatric patient, causes renal toxicity

Principles of Therapy Core Drugs (8 decks)

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