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►Pharmacology > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

1
Q

What is the MOA of clindamycin?

A

Inhibits protein synthesis by binding exclusively to the 50S ribosomal subunit

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2
Q

What are the PKs of clindamycin?

A

Bacteriostatic, but may be bactericidal when present at high concentrations against very susceptible organisms

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3
Q

What are the MOR to clindamycin?

A
  • Altered target sites

- Active efflux

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4
Q

What is the general spectrum of activity of clindamycin?

A
  • Gram + aerobes

- Anaerobes

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5
Q

Gram + aerobes targeted by clindamycin

A

– Methicillin‐susceptible Staphylococcus aureus*, and some CA‐MRSA
– Streptococcus pneumoniae (only PSSP) – resistance is developing
– Group and viridans streptococci

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6
Q

Anaerobes targeted by clindamycin

A

Peptostreptococcus Actinomyces
Propionibacterium
Clostridium spp. (not C. difficile)

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7
Q

How is clindamycin administered?

A

Oral and IV

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8
Q

What is the bioavailability of clindamycin?

A

High. 90%

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9
Q

What is the CSF penetration of clindamycin?

A

Poor

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10
Q

What is the main metabolic path of clindamycin?

A

Liver

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11
Q

Is clindamycin removed with hemodialysis?

A

Clindamycin is NOT removed during hemodialysis

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12
Q

What are the main uses of clindamycin?

A

Anaerobic infections excluding the CNS

Skin and soft tissue infection (PCN allergic patients - CA-MRSA)

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13
Q

Clindamycin SE

A

Most common: nausea, vomiting, diarrhea, dyspepsia

Rare: hepatotoxicity, neutropenia, thrombocytopenia

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14
Q

What are the macrolide drugs?

A

Erythromycin, clarithromycin, and azithromycin

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15
Q

MOA of macrolides

A

Inhibit protein synthesis by reversibly binding to the 50S ribosomal subunit which will lead to the halting of bacterial growth

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16
Q

Macrolide PKs

A

Macrolides typically display bacteriostatic activity, but may be bactericidal when present at high concentrations against susceptible organisms

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17
Q

Erythromycin PKs

A

Time‐dependent bacteriostatic activity

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18
Q

Clarithromycin PKs

A

Time‐dependent bacteriostatic activity

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19
Q

Azithromycin PKs

A

Concentration‐dependent bacteriostatic activity

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20
Q

How does resistance to macrolides occur?

A
  • Altered target sites

- Active efflux

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21
Q

Main MOR to macrolides in US

A
  • Active efflux
22
Q

Main MOR to macrolides in EU

A
  • Altered target sites
23
Q

What is the gene for active efflux of macrolides?

A

Mef

24
Q

What is the gene for altered target sites of macrolides?

A

Erm

25
Q

What is the general spectrum of activity of macrolides?

A
  • Gram positive aerobes
  • Gram negative aerobes
  • Anaerobes
  • Atypical
26
Q

Order that macrolides in decreasing effectiveness against Gram (+) aerobes.

A

(Clarithro>Erythro>Azithro)

27
Q

Order that macrolides in decreasing effectiveness against Gram (-) aerobes.

A

(Azithro>Clarithro>Erythro)

28
Q

What are the specific Gram + aerobes macrolides are effective for?

A 
• Methicillin‐susceptible Staphylococcus aureus (MSSA)*
• Streptococcus pneumoniae (only PSSP) –
resistance is developing
• Group and viridans streptococci
• Bacillus spp., Corynebacterium spp.
29
Q

What are the specific Gram - aerobes macrolides are effective for?

A

• H. influenzae (not erythro), M. catarrhalis,
Neisseria spp.
• Do NOT have activity against any Enterobacteriaceae

30
Q

What macrolides have activity against Mycobacterium avium complex (MAC)?

A

Only azithromycin and clarithomycin

31
Q

What is the oral absorption of the macrolides like?

A

Average to poor with clarithromycin the best at 55%

32
Q

What is the CSF penetration of macrolides?

A

Poor

33
Q

What is the elimination of erythromycin?

A

Erythromycin is excreted in bile and metabolized by CYP450

34
Q

What are the main uses of macrolides?

A

• Respiratory Tract Infections
– Pharyngitis/ Tonsillitis – PCN‐allergic patients
• Uncomplicated Skin Infections
• STDs – Single 1 gram dose of azithro
• MAC – Azithromycin for prophylaxis; Clarithromycin/ Azithromycin for treatment
• Alternative of PCN allergic patients

35
Q

Macrolide SE

A

Most common: nausea, vomiting, diarrhea, dyspepsia

Rare: allergic reaction, cholestatic hepatitis, thrombophlebitis, prolonged QTc, transient/reversible tinnitus

36
Q

What is the interaction of macrolides with cytochrome P450?

A

Erythromycin and clarithromycin ONLY– are inhibitors of cytochrome p450 system in the liver which may increase the concentration of drugs metabolized by this enzyme

37
Q

What is an example of a streptgramin?

A

Quinupristin/Daltopristin (Synercid®)

38
Q

Quinupristin/Daltopristin MOA

A

Each agent acts individually on 50S ribosomal subunits to inhibit early and late stages of protein synthesis

39
Q

Quinupristin/Daltopristin PKs

A

Each one is bacteriostatic alone, but together, they demonstrate time-dependent bactericidal activity

40
Q

What are the mechanisms of resistance to quinupristin and daltopristin?

A
  • Alterations in ribosomal binding sites (erm)

* Enzymatic inactivation

41
Q

What is the general spectrum of activity of quinupristin and daltopristin?

A

-Gram- positive bacteria

42
Q

What are the specific Gram + targets of Synercid®?

A

– Methicillin‐Susceptible and Methicillin‐Resistant Staph aureus and coagulase‐negative staphylococci*
– Streptococcus pneumoniae (including PRSP), viridans streptococcus, Group streptococcus
– Enterococcus faecium (including VRE)
– Corynebacterium, Bacillus. Listeria, Actinomyces
– Clostridium spp. (except C. difficile), Peptococcus, Peptostreptococcus

43
Q

How is Synercid® administered?

A

Only parentally (IM or IV)

44
Q

What is the CSF penetration of quinupristin/daltopristin?

A

Poor

45
Q

What is the elimination of Synercid® via?

A

Liver

46
Q

What is the main use for Synercid®?

A
  • VRE (faecium) bacteremia

* Complicated skin and soft tissue infections due to MSSA or Streptococcus pyogenes

47
Q

What is the effect of Synercid® on other drugs and how does this occur?

A

It can affect the elimination of other drugs because it is a Cytochrome p450 3A4 Inhibitor

48
Q

Quinupristin/Daltopristin SE

A

Most common: venous irritation nausea, vomiting, diarrhea

Rare: rash, myalgias, arthralgias

49
Q

Which one of the following statements regarding Clindamycin is true?
A. Clindamycin is readily removed by either hemodialysis
or peritoneal dialysis
B. Clindamycin is ineffective in the treatment of CNS
infections
C. Clindamycin levels in serum are non‐existent after oral
administration
D. Clindamycin’s activity is limited to Gram‐positive
anaerobes
E. Clindamycin has never been associated with causing C. difficile colitis

A

B. Clindamycin is ineffective in the treatment of CNS

infections

50
Q 
Which one of the following drugs does NOT interact with
Cytochrome P‐450 enzymes?
A. Erythromycin
B. Azithromycin
C. Clarithromycin
D. Telithromycin
E. Quinupristin‐Dalfopristin
A

B. Azithromycin

51
Q

Which one of the following represents the primary mechanism of resistance to Clarithromycin in the US?
A. Mutations in Topoisomerase IV
B. Decreased affinity of clarithromycin binding proteins
present in the bacterial cell wall
C. Increased activity of an antibiotic efflux pump
D. Enzymatic inactivation
E. Alterations in the binding site on the 30S Ribosomal subunit

A

C. Increased activity of an antibiotic efflux pump

►Pharmacology (73 decks)

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