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Drug Mech > More antibiotics > Flashcards

More antibiotics Flashcards

1
Q

Which macrolide is contraindicated during pregnancy?

A

clarithromycin

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2
Q

Name all the macrolides.

A

erythromycin, clarithromycin, dirithromycin, troleandomycin, azithromycin

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3
Q

Which two macrolides do not inhibit cyto-P450 enzyme?

A

azithromycin and dirithromycin

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4
Q

Macrolides can cause what serious side effect?

A

prolongation of QT interval; cardiac arrhythmias

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5
Q

Which macrolide is acid unstable and therefore is enteric coated?

A

erythromycin

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6
Q

What is the mechanism of action of macrolides?

A

blocks 2 steps; translocation of A site to P site and transpeptidation of nascent polypeptide chain

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7
Q

Name the lincosamides.

A

Lincomycin; clindomycin

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8
Q

Name the macrolide spectrum.

A

intermediate, static, 50s

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9
Q

Name the lincosamide spectrum

A

narrow, static, 50s

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10
Q

What is the mechanism of action of lincosamides?

A

same as macrolides (blocks translocation of a site to p site; blocks transpeptidation of polypeptide chain). Also on same binding site on 50s

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11
Q

What are the toxicological effects of lincosamides?

A

hepatotoxicity, GI irritation (less so with clindamycin)

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12
Q

What is the MoA of dalfopristin?

A

Binds to a nearby site, causing a conformational change and enhancing the binding of quinupristin. Also interferes with polypeptide-chain formation

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13
Q

How does quinupristin work?

A

binds to the same location on the 50s as macrolides and lincosamides

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14
Q

What is the mechanism of resistance against quinupristin specifically?

A

production of lactamases to inactivate quinupristin, ribosomal alteration so it can’t bind

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15
Q

What is the mechanism of resistance against dalfopristin specifically?

A

production of acetyltransferases to inactivate it, production of ATP binding efflux proteins

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16
Q

What do streptogrammins inhibit?

A

the drug metabolizing enzyme CYP3A4

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17
Q

What is the activity of streptogrammins

A

CIDAL on 50s (spectrum possibly broad)

18
Q

What are streptogrammins indicated for?

A

VREF (vancomycin-resistant enterococcus faecium) and resistant staph infections

19
Q

Describe the activity of the ketolides

A

intermediate spectrum, cidal, 50s

20
Q

Name the ketolides

A

telithromycin ONLY

21
Q

What is the indication for telithromycin?

A

community-aquired ammonia of mild to moderate severity

22
Q

How does the mechanism of resistance affect ketolides?

A

because telithromycin binds at two different spots on the 50s rRNA, methylases do not inhibit their activity; they only affect the site that telithromycin shares with erythromycin. Telithromycin retains its activity against gram + cocci

23
Q

Why do ketolides have a higher risk of side effects?

A

they inhibit the CYP3a4 isozyme, which results in increased plasma levels of the drug and increases the side effects

24
Q

Ketolides have what specific side effects?

A

prolonged Q-T interval and ventricular arrhythmias (DO NOT mix with macrolides), acute liver failure and severe liver injury, visual disturbances, transient loss of consciousness

25
Q

Ketolides are poor substrates for

A

bacterial protein pumps that mediate active efflux of macrolides

26
Q

Describe the activity of Chloramphenicol

A

static, broad, 50s

27
Q

What population is chloramphenicol contraindicated for and why?

A

newborns; they lack the glucuronyl transferase enzyme - the enzyme that metabolizes the drug. This enzyme is present in the liver

28
Q

What is the MoA of chloramphenicol?

A

inhibits transpeptidation (same as macrolides and lincosamides), but it binds to a site near them, so they are allosteric antagonists

29
Q

Describe the toxicity of chloramphenicol.

A

Inhibits vitamin K production, increases EtOH intolerance, immunodepression, bone marrow depression, aplastic anemia

30
Q

Describe the activity of the oxazolidinones

A

static, gram + only, 50s

31
Q

Name the oxazolidinones

A

linezolid, tedizolid

32
Q

What is the MoA of oxazolidinones?

A

bind to the P-site - preventing the formation of the ribosomal-fMET-tRNA complex and inhibiting the ribosome assembly step

33
Q

What is the mechanism of resistance against the oxazolidinones?

A

mutation of the binding site (linezolid)

34
Q

What is the toxicity of the oxazolidinones?

A

PMC (pseudomembranous colitis) and thrombocytopenia

35
Q

What should not be taken with linezolid?

A

antidepressants, MAOIs, adrenergic agents

36
Q

What are the oxazolidinones indicated for?

A

VREF, nosocomial pneumonia, community acquired pneumonia caused by staph infections

37
Q

Name the pleuromutilins.

A

retapamulin only

38
Q

Describe the activity of the pleuromutilins

A

static (low concentrations) cidal at high, 50s

39
Q

What are the pleuromutilins indicated for?

A

skin infections caused by strep and staph aureus - topical

40
Q

What is the MoA of retapamulin?

A

inhibits p-site interactions, inhibits the enzyme peptidyl transferase, prevents formation of normal acting 50s

41
Q

What is the mechanism of resistance against retapamulin?

A

ribosomal alteration, active efflux no cross resistance

Drug Mech (29 decks)

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