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Pharm Exam 4 > Macrolides and Fluoroquinones > Flashcards

Macrolides and Fluoroquinones Flashcards

1
Q

Macrolides are what general antibiotic type and for what are they named?

A

Protein synthesis inhibitors

Named for large macrolide ring structure

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2
Q

What is a prototype macrolide?

A

Erythromycin

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3
Q

What drug does Erythromycin act like in its antibacterial activity?

A

Penicillin, which is a cell wall inhibitor.

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4
Q

What are the 2 new macrolides that are semisynthetic with an extended spectrum and improved pharmacokinetics?

A

Azithromycin

Clarithromycin

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5
Q

What are the 2 new macrolides, Azithromycin and Clarithromycin used for?

A

Alternatives to penicillins for prophylaxis of bacterial endocarditis

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6
Q

What structure in the Macrolide makes it easily hydrolyzed in the stomach and thereby inactivating a large part of the drug?

A

The lactone ring

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7
Q

What is the erythromycin spectrum of activity (bacteriostatic/cidal), what bacteria is it active against?

A

Narrow spectrum
Bacteriostatic
Gram Positive Cocci

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8
Q

What is the spectrum of activity for Azithromycin and Clarithromycin?

A

somewhat broader, to include activity against gram negatives like H. influenza

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9
Q

What is the macrolide mechanism of action?

A

bind to 50S bacterial ribosome subunit to inhibit ribosomal translocase activity

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10
Q

What does inhibiting translocase activity of the 50S subunit mean?

A

It stops transfer of nascent peptide from A site to P site which stop the next amino acid from being added

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11
Q

Can Erythromycin be bacteriocidal?

A

Yes, depending on concentration of developing bacterial resistance

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12
Q

What is good about narrow spectrum in antibiotics?

A

It reduces the risk of developing bacterial resistance

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13
Q

What is the drawback of erythromycin’s method of delivery and how is it avoided?

A

Destroyed by stomach acid so give w/ enteric coating or as ester salt (estolate, state)

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14
Q

What is the major difference in Azithromycin and Clarithromycin from Erythromycin?

A

Azithromycin and Clarithromycin are not sensitive to stomach acid

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15
Q

If bacteria are resistant to Erythromycin, Azithromycin, Clarithromycin, what does that mean for other drugs that bind the 50S subunit?

A

Bacteria are most likely resistant to those as well

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16
Q

What are the other two 50S subunit binding protein synthesis inhibitor antibiotics?

A

Clindomycin

Chloramphenicol

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17
Q

Of Erythromycin, Azithromycin, and Clarithromycin: which has the longest half-life?

A

Azithromycin (60-70 hrs)

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18
Q

What cells do Azithromycin and Clarithromycin concentrate in?

A

Macrophages

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19
Q

Azithromycin and Clarithromycin, due to their concentration in Macrophages, are useful against what opportunistic infection commonly found in HIV and immunocompromised patients?

A

Mycobacterium avium intracellulaire

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20
Q

Where is erythromycin metabolized?

A

Liver

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21
Q

What is the positive with the longer half-lives of Azithromycin and Clarithromycin?

A

Require dosing only 1-2 times/day

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22
Q

Most common side effects of Macrolides (erythromycin, azithromycin, clarithromycin)?

A

Gi disturbances

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23
Q

What metabolism do macrolides mess with leading to their drug interactions?

A

Inhibit cytochrome P450 drug metabolism by liver

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24
Q

How is Azithromycin metabolized?

A

In urine and bile, so it is safe for a person with liver disease.

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25
Q

What is the most common mechanism for resistance to Macrolides in bacteria?

A

Plasmids encoding erythromycin efflux transporters or methylation enzymes

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26
Q

What is Macrolide dosing for endocarditis prophylaxis that Dr. Ritter gave?

A

500 mg, 30-60 mins before surgery

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27
Q

What is a rare risk factor associated with erythromycin?

A

Cholestatic jaundice from ester salts of erythromycin interrupting bile flow

28
Q

What Penicillin Class is Erythromycin similar to?

A

Penicillin G

29
Q

When would a macrolide be indicated?

A

Patient with penicillin allergy

Bacteria is penicillin resistant

30
Q

What are 2 infections macrolides are commonly used to treat?

A

Respiratory (pneumonia, mycoplasm, Legionella) Skin

31
Q

What is a prototype Fluoroquinolone?

A

Ciprofloxacin

32
Q

What are 3 major advantages of Fluoroquinolones?

A

Oral effectiveness
Activity toward gram positive and gram negative
Safe

33
Q

Is Ciprofloxacin (fluoroquinolone) bacteriocidal or bacteriostatic? What bacteria is it effective against?

A

Bacteriocidal

Gram Positive and Gram Negative

34
Q

What is the method of action of Fluoroquinolone?

A

Inhibit DNA replication by inhibiting bacterial enzyme DNA gyrase

35
Q

Bacterial DNA gyrase is related to what in humans and what are their purposes?

A

Human DNA topoisomerases

Relieve buildup of torsional strain during DNA replication

36
Q

What is an administration consideration with fluoroquinolones?

A

don’t take with dairy or antacids because they bind divalent and trivalent metal cations(like tetracyclines do as well)

37
Q

Which fluoroquinolone is useful for the treatment of UTIs because it does not have as good tissue penetration as Ciprofloxacin and Ofloxacin?

A

Norfloxacin

38
Q

What can block the excretion of fluoroquinolones?

A

Probenecid (used in war to prolong supplies of penicillin [internet])

39
Q

What is huge contraindiction for using fluoroquinolones?

A

Do not use in pregnant/nursing women or children under 18 due to potential to damage growing cartilage (Achilles tendon rupture)

40
Q

What is a notable drug interaction for fluoroquinolones?

A

They increase plasma levels of warfarin

41
Q

Which quinolone (older group) is used only for UTIs?

A

Nalidixic Acid

42
Q

Large Glycopeptide druge whose most important use is treatment of Methicillin Resistant Staphylococcus infections (MRSA)

A

Vancomycin

43
Q

Is vancomycin bactericidal or static?

A

bactericidal

44
Q

What is vancomycin’s method of action?

A

inhibit cell wall synthesis but by different mechanism than penicillin

45
Q

What is vancomycin the DOC for?

A

Treating pseudomembranous colitis from clindamycin

46
Q

What are 2 methods of administration for vancomycin and is it absorbed systemically?

A

Intravenous (IV)
Orally (125 mg 4/day)
No systemic absorption

47
Q

How is vancomycin excreted?

A

Kidney

48
Q

What are 2 side effect risks from vancomycin?

A

Ototoxicity

Nephrotoxicity

49
Q

What is the mechanism of action for bacitracin?

A

Inhibit transport of building blocks of cell wall to outside cell membrane

50
Q

What is the clinical use of bacitracin?

A

Topical treatment of skin & eye bacterial infections

51
Q

With what drugs is bacitracin used in combination?

A

Polymyxin B and Neomycin

52
Q

Clindamycin is an alternative drug for what?

A

Alternative to amoxicillin for endocarditis prophylaxis

53
Q

What is the dosing of Clindamycin before surgery for endocarditis prophylaxis?

A

600 mg 30-60 min before surgery

54
Q

Given how good it is against anaerobes, when should Clindamycinbe be used?

A

Late phase dental infections (bacteroides, prevotella, porphyromonas, fusobacterium)

55
Q

For what is Clindamycin the DOC?

A

Anaerobic infections (e.g. B. fragilis)

56
Q

What are 3 protein synthesis inhibitor drugs that are alternatives to amoxicillin for prophylaxis of endocarditis?

A

Azithromycin
Clarithromycin
Clindamycin

57
Q

What is the major risk with Clindamycin?

A

Enterocolitis due to C. diff overgrowth (superinfection)

58
Q

What is the drug used to treat the superinfection caused by Clindamycin?

A

Vancomycin (vancomycin vanquishes the turds)

59
Q

What are two drugs other than Nalidixic acid and Norfloxacin that are used for UTIs?

A

Nitrofurantoin

Methenamine

60
Q

Which five drugs are used to treat M. tuberculosum?

A
  1. Isoniazid
  2. Ethambutol
  3. Rifampin/Rifampicin
  4. Pyrazinamide
  5. Streptomycin
61
Q

Which are the three major agents used to treat M. tuberculosum?

A
  1. Isoniazid
  2. Ethambutol
  3. Rifampin
62
Q

What is THE major agent used for M. tuberculosum

A

Isoniazid

63
Q

Isoniazid has hepatotoxicity when paired with what other Tb drug?

A

Rifampin/Rifampicin

64
Q

What is the mechanism of action for methambutol?

A

inhibits synthesis of tubercle bacilli cell wall component

65
Q

What is the mechanism of action for Rifampin?

A

inhibits DNA-dependent RNA polymerase

66
Q

What is the tuberculosis drug that is an inducer of hepatic microsomal drug-metabolizing enzymes leading to many drug-drug interactions?

A

Rifampin

67
Q

Why should you use a drug cocktail to treat tuberculosis?

A

Tuberculosis is slow growing with high mutation and resistant rates.

Pharm Exam 4 (8 decks)

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