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Pharmacology Exam 2 > Vancomycin > Flashcards

Vancomycin Flashcards

1
Q

What produces Vancomycin via fermentation?

A

Streptomyces orientalis

Amycolatopsos orientalis

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2
Q

How does Vancomycin work?

A

Inhibits Gram + cell wall biosynthesis

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3
Q

How does Vancomycin inhibit?

A

Binds to side chain D-alanyl terminus before cross linking

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4
Q

Are gram - bacilli or mycobacteria susceptible to Vanco?

A

No

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5
Q

What level of MIC is needed to be considered susceptible for Vanco?

A

4ug/mL

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6
Q

What is the last line of defense against hospital aquired multidrug resistant staph and strep infections?

A

Vancomycin

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7
Q

What mutation is causing the resitance to vancomycin?

A

Peptidoglycan wall formation switch from D-Ala D-Ala to D-Ala D-lactate

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8
Q

Side effect of Vanco?

A

Hypersensitive red skin rash

Potential anaphylaxis

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9
Q

Toxicity to Vanco?

A

Nephrotoxicity due to high concentration

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10
Q

How many membered are the macrocyclic lactones?

A

14 membered

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11
Q

How are macrolide antibiotics produced?

A

Sequential addition of proprionate groups

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12
Q

pKa of amine in erythromycin?

A

8.8

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13
Q

What is translocation?

A

Peptodyl-tRNA is shifted from the A site to the P site

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14
Q

How do macrolides work?

A

Binding reversibly to the P site of the bacterial ribosome

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15
Q

Where do macrolides accumulate?

A

Leukocytes

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16
Q

Why is it good that macrolides accumulate in leukocytes?

A

They are transported into the site of infection

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17
Q

Macrolide binding mainly invovles what?

A

Bacterial 23S RNA

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18
Q

Function of lactone ester hydrolase?

A

Induce to degrade macrolides via hydrolysis of macrocycle

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19
Q

RNA methylase will have what effect on resistance of erythro?

A

Inhibits binding of macrolides to 50S subunit

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20
Q

Mutation of adenine to gunanine at site A2058 results in what?

A

Reduction in binding of erythro and clarithromycin to 23 S ribosomal RNA

21
Q

What will the result of a drug efflux pump be?

A

Resistance to erythro

22
Q

Which organisms exhibit intrinsic resistance to macrolides?

A

Pseudomonas spp.

Enterobacter spp.

23
Q

In macrolyides acidic conditions affect which group?

A

6-OH group

24
Q

If the macrolide group 6-OH is transformed into a ketal what is the result?

A

It’s inactive

25
Q

What is a way to work around the acidity problem with macrolides?

A

USe Clarithromycin which has a 6-OCH3 that blocks ketal formation

26
Q

Besides Clarithromycin what is another alternative to skirt the acid problem of macrolides?

A

Azithromycin

27
Q

Why with Azithromycin negate the acid problem?

A

Replaces the C-9 ketone makine ketal formation impossible

28
Q

Main route of erythromycin metabolism?

A

Demethylation in the liver

29
Q

Main elimination route of erythro?

A

Bile

Small part in urine

30
Q

Half life of erythro?

A

1.5 hours

31
Q

Erythro and Clarithro effect on CYP3A?

A

Bind and inhibit

32
Q

Dirithromycin effect on P450 isozymes?

A

Reduced capacity to inhibit

33
Q

Macrolides that doesn’t have any potential drug interactions?

A

Azithromycin

34
Q

Effect of macrolides on GI system?

A

Stimulate GI motor activity and can cause vomiting, gastric cramps, and abdominal pain

35
Q

two rare occurances due to macrolide use?

A

Stevens-Johnson syndrome

Toxic epidermal necrolysis

36
Q

Long term use of macrolides can cause what reversible problem?

A

Cholestatic hepatitis

Gone after termination of drug use

37
Q

What can erythro effect in children whose mothers took it while in late stages of pregnancy?

A

Pyloric stenosis

38
Q

Where is erythro most effectively absorbed?

A

Tissues and phagocytes

39
Q

What is erythromycin estolate?

A

Prodrug of erythromycin

40
Q

Benefit of Erythromycin estolate?

A

More lipophilic

Increase oral absorption

41
Q

What is erythromycin estolate used to treat?

A

Group A beta hemolytic strep
Primary Syphillis
Alpha hemolytic strep

42
Q

What is erythromycin ethyl succinate?

A

Prodrug of erythromycin

43
Q

What is more effective against Haemophilis influenzae than clarithromycin

A

Clarithromycin metabolite 14-(R) hydroxy

44
Q

How many members in Azithromycin ring?

A

15, due to removal of Carbon 9 to prevent ketal formation

45
Q

Half life of Azithromycin?

A

68 hours

46
Q

Which elements can interefere with Azithromycin absorption into tissues?

A

MAgnesium and aluminum

47
Q

Major route of elimination for Azithromycin?

A

Biliary

48
Q

What bacteria does Azithromycin kill better than eyrthro or clarithro?

A

Gram -

Pharmacology Exam 2 (9 decks)

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