Macrolides Flashcards

1
Q

Macrolides include

A

erythromycin, clarithromycin, azithromycin

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2
Q

Clarithromycin and azithromycin are

A

semi-synthetic derivatives of erythromycin

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3
Q

Macrolides contain ____ in their structure

A

lactone ring attached to several sugars

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4
Q

Erythromycin and clarithromycin are ____ membered rings

A

14

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5
Q

Azithromycin is a ___ membered ring

A

15

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6
Q

Minor structural modifications between the 3 drugs contribute to

A

improved acid stability
tissue penetration
broadened spectrum of activity

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7
Q

Macrolides MOA

A

reversibly bind to domain V of 23S ribosomal RNA of the 50s subunit of the ribosome

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8
Q

The result of macrocodes binding to 23S rRNA

A

blocks transpeptidation and indirectly interferes with translocation step

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9
Q

Macrolides are bactericidal/bacteriostatic

A

bacteriostatic

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10
Q

Macrolides spectrum coverage gram +

A

most active in vitro against gram + cocci and bacilli

Gram +: s. pneumoniae, streptococcus, staphylococci including MSSA, corynebacterium, listeria monocytogenes

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11
Q

Gram + activity: order of which drug works the best to the least

A

Clarithromycin> erythromycin> azithromycin

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12
Q

Macrolides spectrum coverage gram -

A

modest gram - activity
h. influenzae, Neisseria, pasteurella multocida, bordetella pertussis, c. jejuni, mortadella catarrhalis, h. pylori, bartonella, rickettsia

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13
Q

Gram - activity: order of which drug worst the best to least

A

Azithromycin> clarithromycin> erythromycin

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14
Q

Macrolides atypicals coverage

A

mycoplasma pneuomoniae, chlamydia (pneumoniae and trachomatis), mycobacterium, legionella, spirochetes (syphilis), protozoa

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15
Q

Macrolides cover most

A

respiratory pathogens

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16
Q

Macrolides do not cover

A

MRSA
enterococci
enterobacteriaceae
pseudomonas aerugingsa and other non-lactose fermenting gram -

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17
Q

Macrolide resistance mechanisms in which organisms

A

strep and staph

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18
Q

Alteration of the drug binding site on the ribosome is caused by ____; this is ___ level resistance

A

methylation/erm gene; high

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19
Q

Drug efflux is caused by ___ in staph and ____ in strep; this is ___ level resistance

A

msr, mef; low

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20
Q

What other 2 resistance mechanisms can staph and strip have against macrolides?

A

drug modification through enzymes and target mutation (altered binding to ribosome)

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21
Q

Erythromycin formulations

A

oral, IV, topical (ophthalmic)

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22
Q

Erythromycin base is ___ by stomach acid and requires ___

A

destroyed; enteric coating

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23
Q

Erythromycin ____ are better absorbed and more acid resistant

A

esters

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24
Q

Erythromycin ester examples

A

erythromycin stearate, erythromycin estolate, erythromycin ethylsuccinste

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25
Q

Which erythromycin formulation is best for oral use?

A

erythromycin estolate

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26
Q

Erythromycin base in incompletely absorbed from the

A

upper small intestine

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27
Q

Where do enteric coated tablets dissolve?

A

duodenum

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28
Q

Food should/should not be taken with erythromycin base, stearate, or ethylsuccinate

A

should NOT

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29
Q

Food should/should not be taken with erythromycin estolate

A

should

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30
Q

Erythromycin distribution to CSF

A

poor, inflamed meninges only 7-25%

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31
Q

Erythromycin is ___ protein bound

A

highly

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32
Q

Erythromycin is mostly eliminated in

A

bile/feces

33
Q

Erythromycin does/does not require renal adjustment

A

does not

34
Q

1/2 life of Erythromycin may be prolonged in patients with

A

anuria

35
Q

Can Erythromycin be removed by hemodialysis?

A

no

36
Q

Does Erythromycin cross placenta?

A

yes

37
Q

Erythromycin cross into breast milk?

A

yes

38
Q

Erythromycin indications

A
respiratory tract infections
SSTI
Chlamydia in infants
diphtheria
pertussis
gastroparesis
39
Q

Erythromycin is used to treat chlamydia in

A

infants

40
Q

Erythromycin is the only FDA approved macrolide to treat

A

diphtheria

41
Q

Erythromycin is used in gastoparesis as off label

A

pro kinetic agent

42
Q

Erythromycin adverse effects

A

GI toxicity
cardiac toxicity (QT prolongation, tachycardia)
hepatotoxicity

43
Q

Hepatotoxicity with Erythromycin is associated with

A

long use (10-20 days after start)

44
Q

Hepatotoxicity symptoms with Erythromycin will resolve

A

when drug is discontinued

45
Q

Hepatotoxicity is greatest with which macrolide?

A

Erythromycin

46
Q

Clarithromycin formulations

A

oral tablets, ER tablets, oral powder for suspension

47
Q

Clarithromycin is absorbed ___ from GI tract

A

readily

48
Q

Clarithromycin has a large amount of ____ that decreases bioavailability by 50-55%

A

first pass metabolism

49
Q

Clarithromycin should be given

A

with or without food

50
Q

Clarithromycin ER should be given with food to

A

improve bioavailability

51
Q

Clarithromycin parent drug and ____ achieve high intracellular concentrations in the body

A

active metabolite

52
Q

Clarithromycin is metabolized by

A

liver

53
Q

Clarithromycin metabolism is ____ and results in higher doses with ____

A

saturable; longer 1/2 lives

54
Q

Clarithromycin has ____ kinetics

A

non linear

55
Q

Clarithromycin has 40-70%

A

protein binding

56
Q

Clarithromycin tissue penetration is

A

good

57
Q

How much Clarithromycin is excreted in urine?

A

20-40%

58
Q

Clarithromycin needs dosage adjustments in patients with

A

CrCl < 30 ml/min

59
Q

Clarithromycin needs/does not need adjustment in hepatic impairment

A

does not

60
Q

Clarithromycin adverse effects

A

GI distress but to lesser degree than erythromycin
less risk of cardio toxicity compared to erythromycin
less hepatotoxicity compared to erythromycin

61
Q

Clarithromycin can interact with

A

concomitant anti arrhythmic drugs or drugs that prolong QT

62
Q

Clarithromycin indications

A

respiratory tract infections
h. pylori in combo with omeprazole and amoxicillin
mycobacterial infections

63
Q

Azithromycin formulations

A

oral (ZPAK and Tri-Pak)
oral powder
IV
ophthalmic

64
Q

Azithromycin oral absorption

A

PO absorbed rapidly but incompletely; 30-40%

65
Q

Azithromycin distributed ___ throughout body

A

widely; extensive tissue distribution

66
Q

Azithromycin can achieve ___ concentrations within cells (including phagocytes)

A

high

67
Q

Azithromycin major excretion

A

biliary

68
Q

Only ___ % is excreted in the urine

A

12

69
Q

Azithromycin has a ___1/2 life due to extensive tissue sequestration and binding

A

long

70
Q

Azithromycin adverse effects

A

GI distress lesser degree than erythromycin
less cardio toxicity than erythromycin
less hepatotoxicity than erythromycin

71
Q

Drug that Azithromycin can interact with

A

concomitant anti arrhythmic and QT prolonging

72
Q

Azithromycin indications

A

respiratory tract infections
chlamydia
pertussis
mycobacteria infections

73
Q

Azithromycin is favored in treating respiratory tract infections because

A

broader spectrum, ease of dosing, better tolerability

74
Q

Which macrolide has the longest 1/2 life?

A

azithromycin

75
Q

Which macrolide has the created bioavailability?

A

clarithromycin

76
Q

ZPAK dosing

A

500mg po on day 1 then 250mg po on days 2-5

77
Q

eryhthromycin and clarithromycin strongly inhibit

A

CYP3A4

78
Q

Azithromycin is ___ to be involved in drug interactions

A

much less likely

79
Q

Which macrolide has the greatest potential to cause side effects?

A

erythromycin