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Principles of Therapy Core Drugs > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

1
Q

What is the classification of Gentamicin and Amikacin?

A

Aminoglycosides

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2
Q

What is the mechanism of action of Aminoglycosides?

A

Inhibits bacterial protein synthesis by binding strongly

to 30S-subunit, concentration-dependent killing

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3
Q

What are the therapeutic indications of Aminoglycosides? (3)

A
  • Life-threatening aerobic Gram negative infections
  • Limited Gram positive action
  • Pseudomonas aeruginosa
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4
Q

What are aminoglycosides used in conjunction with and why?

A
  • used in combinations for severe infections
  • Penicillin: staphylococci, streptococci,
    enterococci
  • metronidazole / clindamycin: anaerobic infections
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5
Q

What is the recommended dosage of Aminoglycosides and why?

A

Single daily doses, due to prolonged post-antibiotic effect

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6
Q

When are aminoglycosides not given in a single daily dose?

A

In children, critically ill patients and when used with penicillin

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7
Q

What is considered to be the standard aminoglycoside in many centres?

A

Gentamicin

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8
Q

How is gentamicin administered?

A

IM

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9
Q

Describe the distribution of gentamicin

A

rapidly distributed in the extracellular fluid and tissue

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10
Q

What is the half-life of gentamicin and what increases this?

A

2-3 hours, but increases during renal insufficiency or in neonates

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11
Q

What is the effect of gentamicin on the CNS?

A

Minimal effect, crossing into BBB is poor

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12
Q

How is gentamicin excreted?

A

eliminated unchanged by glomerular filtration within 24 hours

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13
Q

What are the adverse effects of gentamicin? (9)

A
  • Nephrotoxicity
  • Ototoxicity
  • Neuromuscular blockade, headache, tremor, electrolyte disturbances, hepatic damage, rashes and fever
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14
Q

What is the classification of Doxycycline?

A

Tetracyclines

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15
Q

What is the mechanism of action of Tetracyclines?

A

Binds reversibly to the 30S subunit of the bacterial ribosome, blocking the binding of amino-acyl-tRNA to the acceptor site on the mRNA-ribosome complex. This prevents addition of amino acids to the growing peptide chain.

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16
Q

What is the spectrum of activity of Tetracyclines?

A

broad

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17
Q

What are the therapeutic indications of Tetracyclines? (6)

A
  • G+, G-, anaerobes
  • Rickettsia, Chlamydia, Vibrio cholerae, Mycoplasmas and some protozoa
  • Leptospirosis, gas-gangrene, tetanus (Oxytetracycline)
  • Acne (Doxycycline and minocycline)
  • Malaria
  • Prophylaxis
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18
Q

How do Tetracyclines mainly differ?

A

Their GIT absorption

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19
Q

Describe the absorption of newer generation Tetracyclines?

A

lipid soluble and are completely absorbed even in the presence of food

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20
Q

What inactivates Tetracyclines?

A

milk and antacids

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21
Q

What are the adverse effects of Tetracyclines? (6)

A
  • GIT upsets, nausea, vomiting
  • Damage to gut flora causes superinfection with
    pathogens (Candida)
  • Pseudomembranous colitis (life-threatening)\
  • Bone growth retardation
  • Teeth discolouration and enamel hypoplasia
  • Hepato- and nephrotoxic.
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22
Q

What are the contraindications of Tetracyclines?

A

children under 8

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23
Q

What is the classification of Erythromycin and Azithromycin?

A

Macrolides

24
Q

What is the mechanism of action of Macrolides?

A

Bind to the 50S bacterial ribosomal subunit and inhibit protein synthesis by having an effect on translocation

25
Q

What is the spectrum of activity of Macrolides?

A

Similar to Penicillin G

26
Q

What are the therapeutic indications of Macrolides? (5)

A
  • Legionnaire’s disease
  • whooping cough
  • Mycoplasma pneumoniae
  • Chlamydia
  • Alternative in penicillin-allergic patients
27
Q

How is Erythromycin administered? (and why)

A

Orally, it is acid-labile and must be administered with enteric coating to protect the antibiotic until it reaches the absorption site in the duodenum.

28
Q

What are the 2 oral forms of Erythromycin and which one has better absorption?

A
  • stearate salt or the ester (estolate) forms

- estolate has the best absorption

29
Q

Describe the distribution of Ethyromycin

A

Extensively distributed into most tissues, including prostate fluid, crosses placenta but not BBB

30
Q

What is the half-life of Ethyromycin?

A

1.5-2 hours

31
Q

Describe the protein binding of Ethyromycin?

A

protein-binding is high

32
Q

How is Ethyromycin metabolised and excreted?

A

Partially metabolized in the liver and excreted in bile, 2-5% is excreted unchanged in the urine.

33
Q

What are the adverse effects of Ethyromycin? (3)

A
  • Well tolerated, one of safest antibiotics
  • Prolologed use of estolate: hepatotoxicity
  • Erythromycin metabolites: increase serum concentrations of drugs to toxic levels and increases bioavailability of digoxin.
34
Q

What is the classification of Clindamycin?

A

Lincosamide

35
Q

What is the mechanism of action of Clindamycin?

A

Inhibits protein synthesis by binding to 50S ribosomal

subunits interfering with the formation of initiation complexes and with the aminoacyl translocation reaction

36
Q

What are the therapeutic indications of Clindamycin? (2)

A
  • gram-positive infections in patients allergic to penicillins
  • sensitive staphylococcal and anaerobe infections such as Bacteroides species
37
Q

Describe the distribution of Clindamycin

A

widely distributed in most body tissues and fluids except the cerebrospinal fluid

38
Q

Describe the absorption of Clindamycin

A

well absorbed from the GIT

39
Q

What is the half-life of Clindamycin?

A

2-3 hours

40
Q

What % of Clindamycin binds to plasma proteins?

A

> 90%

41
Q

How is Clindamycin metabolised and excreted?

A

hepatic metabolism and excretion in the bile

42
Q

What are the adverse effects of Clindamycin? (2)

A
  • GIT problems: diarrhoea, nausea and vomiting

- Skin rashes

43
Q

What is the classification of Chloramphenicol?

A

Amphenicol

44
Q

What is the mechanism of action of Chloramphenicol?

A

Binds reversibly to the 50S subunit of the bacterial ribosome and inhibits the peptidyl transferase-enzyme during protein synthesis

45
Q

What is the spectrum of activity of Chloramphenicol?

A

broad

46
Q

What are the therapeutic indications of Chloramphenicol?(5)

A
  • Serious infections such as meningitis
  • Life- threatening epiglottitis caused by the organism H. influenzae
  • Typhoid fever
  • Bacterial eye infections
  • Not for prolonged infections and for
    prophylaxis
47
Q

How is Chloramphenicol succinate administered?

A

parenterally

48
Q

How does Chloramphenicol succinate yield free chloramphenicol?

A

Hydrolysis (water-soluble)

49
Q

How is Chloramphenicol succinate administered?

A

orally

50
Q

Describe the absorption of Chloramphenicol

A

rapidly absorbed and is about 80% bioavailable

51
Q

Describe the distribution of Chloramphenicol

A

widely distributed to virtually all tissues and body fluids, including the central nervous system and cerebrospinal fluid

52
Q

What % of Chloramphenicol is bound to protein?

A

30-50%

53
Q

What is the half-life of Chloramphenicol?

A

1.5-4 hours

54
Q

How is Chloramphenicol metabolised and excreted?

A

metabolized by the liver and conjugated with glucuronic acid and eliminated in the urine

55
Q

What are the adverse effects of Chloramphenicol? (6)

A
  • severe, idiosyncratic depression of bone marrow
  • fatal aplastic anaemia
  • “grey baby syndrome”
  • GIT effects
  • Optic or peripheral neuritis
  • Jarisch-Herxheimer-like reactions

Principles of Therapy Core Drugs (8 decks)

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