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Pharm FA16 > Antimicrobials--Final > Flashcards

Antimicrobials--Final Flashcards

1
Q

Name 2 groups of concentration dependent drugs

A

1) aminoglycosides (Gentamicin & Amikacin)

2) Fluoroquinolones (Enrofloxacin & other -floxacins)

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2
Q

Name the 2 classes of water soluble drugs

A

1) beta-lactams

2) Aminoglycosides

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3
Q

Though combination therapy with beta-lactams can be effective, which type of antimicrobial should you not combine it with?

A

Bacteriostatic drug (will slow the growth and beta lactam won’t be as effective)

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4
Q

Which type of organisms are inherently resistant to beta-lactams?

A

those that lack a cell wall (i.e. Mycoplasma, Chlamydia)

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5
Q

The purpose of clavulonic acid?

A

it’s a beta lactamase inhibitor; Combine it with beta-lactams to minimize destruction

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6
Q

This beta-lactam’s smaller size facilitates its delivery through microbial porins; it is still susceptible to beta lactamases though so it’s usually combined with ____?

A

Ticarcillin

Clavulanic acid

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7
Q

As a general rule, the spectrum of penicillins includes?

A

(Penicillin, Ampicillin, Amoxicillin, Ticarcillin)

Anaerobes, Gram (+), and easy Gram (-)

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8
Q

This extended spectrum penicillin is more specific for gram negative organisms

A

Ticarcillin (gets pseudomonas, serratia, etc.)

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9
Q

How does Meropenem differ from Ticarcillin?

A

Share a similar spectrum, but Meropenem is more effective and more resistant to destruction

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10
Q

The later generations cephalosporins include a greater range of ______ in their spectrum

A

anaerobes

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11
Q

Of the various preparations of penicillin, which:

1) has the fastest absorption
2) has the longest duration

A

1) Procaine ester

2) Benzathine ester

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12
Q

Which beta lactam is characterized by high protein binding, giving it a half life of >5 days?

A

Cefovecin (convenia)

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13
Q

How do the penicillins and cephalosporins differ in their half lives?

A

Penicillins have shorter (1-2 hr) half lives, requiring TID or QID dosing

Cephalosporins are around 4-5 hours

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14
Q

Name 2 side effects that can be seen with beta lactams

A

Hypersensitivity (Type 1, allergy)… more common with penicillins than cephalosporins

Electrolyte imbalance (Na or K salt penicillin)

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15
Q

Cell wall inhibitor that isn’t a beta lactam?

A

Vancomycin (Glycopeptide)

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16
Q

This drug is used to treat MRSA and its use is prohibited in food animals

A

Vancomycin

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17
Q

Name the major drug classes that are ribosomal inhibitors

A

Aminoglycosides (Gentamicin & Amikacin)

Tetracyclines (-cycline drugs)

Phenicols (-enicol drugs)

lincosamides (clindamycin)

Macrolides (Tilmicosin)

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18
Q

This group of drugs is ionized in the plasma and is attracted to the negative charge of cell membranes

A

aminoglycosides

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19
Q

This group of drugs has the broadest gram neg spectrum (and is most effective)

A

Aminoglycosides

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20
Q

Which type of organisms show inherent resistance to aminoglycosides?

A

Obligate or facultative anaerobes (because they need to be actively transported into the cell)

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21
Q

For which organism should aminoglycosides not be used as the sole antimicrobial agent?

A

Staphylococcus (combo therapy only)

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22
Q

When comparing Amikacin and Gentamicin, which is less susceptible to destruction?

A

Amikacin (larger side group)

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23
Q

Because the aminoglycosides are a weak_______, they are most effective in what type of environment?

A

Weak bases; most effective in alkaline pH

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24
Q

Though they have a short half-life, aminoglycosides can be dosed once daily due to?

A

Long post antibiotic effect

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25
Q

Main adverse event seen with aminoglycoside use? Best way to avoid it in at risk patients?

A

Nephrotoxicity; prolong dosing interval (don’t lower dose)

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26
Q

Compared to aminoglycosides, the other ribosomal inhibitors are? (3 differences)

A

bacteriostatic
Time dependent
Lipid soluble

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27
Q

Which drug class targets the 30s subunit?

A

Tetracyclines (inhibits translocation)

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28
Q

Which class of drugs is considered “broad spectrum” and is also good for intracellular organisms?

A

Tetracyclines (Doxy mainly for intracellular)

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29
Q

Describe the dietary interactions of tetracyclines

A

most shouldn’t be given with food because Ca and Mg can prevent absorption

Doxycycline is exception

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30
Q

Though most tetracyclines are _____ soluble, Doxycycline is _____ soluble

A

Most are water; doxy is lipid (gets into cells!)

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31
Q

Name 3 unique adverse events associated with tetracyclines

A

1) brown discoloration of growing teeth (don’t use in animals < 3 months)
2) esophageal erosion in cats (follow with water!)
3) disruption of microflora (don’t give orally to ruminants)

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32
Q

2 unique indications for tetracyclines

A

1) inhibition of inflammatory metalloproteinases

2) HW disease (doxy)

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33
Q

Two modifications that improve Florfenicol compared to Chlorampehicol

A

Nitrous group replaced with sulfur group (reduced toxicity)

Contains fluorine (reduces resistance)

34
Q

Main mechanism of resistance to phenicols?

A

Acetylation

35
Q

Compared to tetracyclines, the spectrum of phenicols is better at?

A

Anaerobes (and less effective at intracellular)

36
Q

This drug is associated with a lethal type B reaction that can lead to aplastic pancytopenia

A

Chloramphenicol

37
Q

Name 2 unique characteristics of Clindamycin

A

Can accumulate in WBCs

Can penetrate biofilm (periodontal disease)

38
Q

Because this drug is eliminated solely in the bile, it can disrupt GI microflora (Pseudomembranous entercolitis) which can be lethal to horses

A

Clindamycin

39
Q

Because this drug can accumulate in alveolar macrophages, it is useful in respiratory infections (i.e. shipping fever in cattle)

A

Tilmicosin

40
Q

Tilmicosin can also stimulate beta-3 receptors, causing?

A

lethal tachycardia (some spp.)

41
Q

Name the drugs that are nucleic acid inhibitors (3)

A

Enrofloxacin (and other -floxacin drugs)
Metronidazole
Rifampin

42
Q

Fluoroquinolone MOA?

A

targets bacterial topoisomerases (II and/or IV)

43
Q

Compare the two topoisomerases targets by Fluoroquinolones

A

II (DNA gyrase)–unwinding; more important in gram neg

IV–supercoil repair; more important in gram +

44
Q

As far as pH is concerned, Flurorquinolones are _____

A

amphoteric (but tend to act more as weak bases)

45
Q

Though less effective than aminoglycosides, this class of drugs is also broad spectrum toward gram negative organisms

A

Fluoroquinolones

46
Q

The later generations of fluoroquinolones are less susceptible to destruction and include _____ in their spectrum

A

anaerobes

47
Q

Describe resistance to fluoroquinolones

A

results from stepwise mutations that increase the MIC with each step; after 1-2 mutations, efflux pumps increase and causes MDR

48
Q

Main downside of using the human generic Ciprofloxacin in animals?

A

Decreased oral bioavailability

49
Q

Impact of hepatic metabolism on enrofloxacin?

A

creation of active metabolite (Ciprofloxacin)… contributes to activity of drug

50
Q

This side effect limits the dosing maximum of enrofloxacin in cats

A

acute retinal degeneration (drug accumulates due to lack of efflux pump)

51
Q

Spectrum of metronidazole is limited to?

A

anaerobes (excellent)

52
Q

This drug is associated with a risk of CNS toxicity in dogs&raquo_space; cats

A

Metronidazole

53
Q

MOA of Rifampin?

A

inhibits RNA polymerase

54
Q

This drug should always be used in combination therapy because resistance to it develops rapidly

A

Rifampin

55
Q

It’s important to warn clients about this weird side effect of rifampin

A

causes discoloration (orange) of body secretions

56
Q

Sulfonamide MOA?

A

inhibits synthesis of folic acid (2 points)
1) sulfonamide mimics PABA–>inhibits synthetase (static)

2) Trimethoprim inhibits reductase (cidal)

57
Q

Describe the spectrum of sulfonamides

A

fair to good toward everything (excellent at nothing)

can’t get organisms lacking a cell wall

58
Q

Which classes of drugs require a cell wall to be effective?

A

Beta lactams

Sulfonamides

59
Q

Dogs may be predisposed to toxicity with which group of drugs?

A

sulfonamides (undergo hepatic acetylation)

60
Q

Dogs on this drug are at risk for hypersensitivity that manifests as keratitis sicca

A

Sulfadiazine (also reversible hypothyroidism)

61
Q

3rd generation fluoroquinolone approved for use in cats?

A

Pradofloxacin

62
Q

Generally how do mechanisms of resistance differ between bacteria and fungi?

A

Fungi have more inherent resistance, but acquired resistance is less common

63
Q

MOA and spectrum of amphotericin B?

A

forms pores in fungal cell wall by binding ergosterol (also immunomodulatory)

Targets everything except dermatophytes

64
Q

The only type of fluids amphotericin B can be given with?

A

5% dextrose (other fluids may precipitate the drug)

65
Q

Which preparation of amphotericin B is actively phagocytozed by macroophages and allows safer delivery of higher concentrations of drug?

A

LAmB (liposomal)

66
Q

Two mechanisms by which Amphotericin causes nephrotoxicosis.

A

Renal arterial vasoconstriction (immediate–ischemia)

Distal tubular permeability (loss of ions and K)

67
Q

This is dose-dependent side effect of Amphotericin?

tx?

A

Anaphylactoid reaction (antihistamines & glucocorticoids)

68
Q

This antifungal is characterized by a lag time to efficacy due to its long half-life?

A

Itraconazole (half life is 2-3 days)

69
Q

Itraconazole MOA?

A

inhibits CYP450 to prevent ergosterol synthesis

70
Q

Which antifungal class has to broadest spectrum?

A

Imidazoles

71
Q

Name 2 antifungals that exhibit synergistic effects when given together?

A

Itraconazole & Amphotericin B

72
Q

Griseofulvin MOA?

A

inhibits division by binding microtubules

73
Q

Spectrum of Griseofulvin

A

dermatophytes only

74
Q

Which preparation of Grisofulvin is most orally available? How can you enhance the other?

A

Ultramicrosize

enhance microsize by giving with fatty meal

75
Q

Which drug has to be incorporated into keratin which results in a 4-6 week window before efficacy occurs?

A

Griseofulvin

76
Q

Two important side effects of grisofulvin?

A

Type B (cats) bone marrow dsycriasias & neuro tox

Teratogenic (don’t give to pregnant animals)

77
Q

Terbinafine MOA?

A

inhibits squalene (precursor to cell wall)

78
Q

Which antifungal is known to accumulate in lipids of the skin?

A

Terbinafine

79
Q

One way to improve the spectrum of terbinafine?

A

Combination therapy

80
Q

Spectrum of Iodides?

A

Sporotrichosis only

Pharm FA16 (6 decks)

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