Lec. 8: Macrolides Flashcards

1
Q

Name three macrolides.

A
  1. Erythromycin
  2. Clarithromycin
  3. Azithromycin
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2
Q

What binds to the 50S ribosomal subunit and inhibits proteins synthesis, is bacteriostatic, and will develop resistance quickly?

A

Erythromycin

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3
Q

What are the three mechanisms of resistance seen in erythromycin?

A
  1. Decreased transport
  2. Modification of ribosomal target by methylases
  3. Hydrolysis of drug by esterases
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4
Q

Erythromycin is a ? spectrum drug that has high uptake in gram-?. It is well distributed to soft tissues and does/does not cross the BBB.

A
  1. Narrow
  2. Gram-Positive
  3. Does not
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5
Q

Erythromycin is concentrated in the liver and is excreted where?

A

In the bile

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6
Q

T or F. Erythromycin inhibits cytochrome P450 enzyme.

A

True

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7
Q

What is an effect of inhibition of cytochrome P450 enzyme?

A

Increased concentration of concurrent drug that are substrates for CYP3A

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8
Q

Erythromycin is second after ? for gram-postive infections.

A

Pencillin G

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9
Q

What can be given to treat Listeria monocytogenes, corynebacterium deptheria, lyme disease, legionnaire’s disease, and mycoplasma pneumonia infections?

A

Erythromycin

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10
Q

What is more acid-stable than erythromycin, is similar to effectiveness to penicillins V, and the absorption of oral dose increase with food?

A

Clarithromycin

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11
Q

How does clarithromycin compare to erythromycin?

A

Clarithromycin has a longer half-life, has slightly better activity against gram-positive, and has more anaerobic coverage.

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12
Q

Clarithromycin inhibits what enzyme?

A

Cytochrome P450 3A4 enzyme

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13
Q

Which is a stronger inhibitor of cytochrome P450 3A4 enzyme, erythromycin or clarithromycin?

A

Erythromycin

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14
Q

What drug has a very long half life (35-40 hours), absorption of oral dose is REDUCED by food, and is more acid-stable than erythromycin?

A

Azithromycin

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15
Q

What is a major advantage of Azithromycin over other macrolides?

A

No inhibition of CYP enzymes

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16
Q

Z-pack is associated with what macrolide?

A

Azithromycin

17
Q

What drug inhibits protein synthesis, binds to the 50S subunit of ribosome, has cross-resistance to the macrolide antibiotic, and penetrates bone?

A

Clindamycin

18
Q

What drug is useful for orodental pathogens and has prophylactic coverage when allergic to penicillin?

A

Clindamycin

19
Q

What inhibits protein synthesis by binding to the 30S ribosome, is bacteriostatic, is a BROAD spectrum drug that acts on both gram positive and gram negative drugs?

A

Tetracyclines

20
Q

T or F. Resistance to one tetracycline provides resistance to all tetracyclines.

A

True

21
Q

Tetracycline is inhibited by ?. Some examples are Ca++, Mg++, Fe++, and Al+++. It should not be given with dairy products or iron-containing supplements.

A

Di- and trivalent cations

22
Q

Does tetracycline cross the placenta and move into breast milk?

A

Yes

23
Q

Superinfections are common with tetracyclines. Which one is more completely absorbed and least likely to cause problems?

A

Doxycycline

24
Q

Chelation of Ca++ when giving ? results in what?

A
  1. Tetracyclines

2. Discoloration of teeth when given during gestation or to children, and induced staining of the dentition in adults

25
Q

Depression of bone growth, hepatic toxicity from large paraenteral dose, vestibular toxicity, and photosensitivity is common with what drug?

A

Tetracyclines

26
Q

Vestibular toxicity is characteristic of what tetracycline?

A

Minocycline

27
Q

What is the difference in doxycycline and minocyclines?

A

Doxycyclines require fewer doses and have less GI disturbances. Minocylcline are useful for prophylactic treatment for meningococcal infection, but frequently cause vomiting and vertigo.

28
Q

What drug penetrates the CSF, and causes effects on bacterial DNA replication?

A

Metronidazole

29
Q

How does metronidazole become active?

A

Through enzymatic reduction of the drug by the organism

30
Q

What drug inhibits P450 isozyme, CYP 2C9, can be combined with beta-lactam for serious acute orofacial infections, and is active against gram-negative anaerobes?

A

Metronidazole

31
Q

Induced staining of the dentition in adults is cause by what tetracycline?

A

Minocycline