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MNI (immuno pharm) > L29- Protein Synthesis Inhibitors I > Flashcards

L29- Protein Synthesis Inhibitors I Flashcards

1
Q

list the protein synthesis inhibitors

A
  • tetracyclines
  • glycylcyclines
  • aminoglycosides
  • macrolides
  • chloramphenicol
  • clindamycin
  • streptogramins
  • linezolid
  • mupirocin
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2
Q

Protein Synthesis Inhibitors:

  • bacterio-(static/cidal)
  • (2) MOA
  • (3) MOA’s effects that are basis for AEs
A

1- bacteriostatic (mostly, aminoglycoside is only bacteriocidal)

2- binds bacterial ribosome (70S = 50S + 30S) —- differs from eukaryotic ribosome (80S = 60S + 40S)

3- binds mammilian mitochondrial ribosome (due to resemblance to bacterial ribosome) => AEs

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3
Q

______ is the only bacteriocidal protein synthesis inhibitor

A

aminoglycosides

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4
Q

list tetracyclines

A
  • doxycycline
  • minocycline
  • tetracycline
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5
Q

Tetracycline MOA:

  • enters bacteria via (1) in order to concentrate drug intracellularly
  • binds (ir-/reversibly) to (3) in order to prevent (4) process
A

1- passive diffusion + energy dependent transport

2- reversibly
3- 30S subunit of ribosome
4- attachment of aminoacyl tRNA

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6
Q

______ antibiotic works by binding 30S subunit of ribosome in order to prevent tRNA attachment

A

tetracyclines (T for tRNA)

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7
Q

describe the prevalence and mechanisms of resistance to Tetracyclines

A

-widespread resistance (due to overuse)- usually plasmid related

1) impaired influx OR inc efflux via plasmid-encoded protein pump
2) bacterial protein production to interfere with binding to ribosomes
3) enzymatic inactivation

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8
Q

Tetracyclines are most commonly used to treat (1) and (2)- (3) is also a popular use of tetracyclines.

A

1- severe acne
2- rosacea

3- empiric therapy for CA-pneumonia

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9
Q

Tetracycline (monotherapy) is the drug of choice for….. (hint- 7)

A
  • chlamydia
  • Mycoplasma pneumoniae (CA-pneumonia)
  • Lyme disease
  • Cholera
  • Anthrax prophylaxis
  • Rickettsia (Rocky Mountain Spotted Fever)
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10
Q

Tetracycline is used in combination therapy for the following conditions….

A
  • H. pylori
  • Malaria prophylaxis and Tx (doxycycline)
  • Tx of plague, tularemia, brucellosis
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11
Q

Tetracycline Pharmacokinetics:

  • (1) describe general oral bioavailability among the tetracyclines
  • accumulates in (2) tissues
  • (3) main route of elimination, (4) is the exception
A

1- variable — doxycycline is lipid soluble, therefore parenterally admin. preferred

2- liver, kidney, spleen, skin

3- urine
4- Doxycycline –> bile

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12
Q

Tetracycline AEs:

  • (1) common AEs
  • (2) are the main contraindications due to (3) AEs
  • (4) are seen with doxycycline and minocycline
  • (5) via renal accumulation
  • (6) via skin accumulation
A

1- n/v/d or superinfections

2- pregnancy, children <8y/o (crosses into placenta and breast milk — teratogen)
3- discoloration and hypoplasia of teeth (via Ca binding), stunting of growth, fatal hepatotoxicity in pregnant Pts (high doses + partial hepatic insufficiency in pregnancy)

4- dizziness, vertigo
5- exacerbation of renal dysfunction
6- photosensitive

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13
Q

list the glycylcyclines

A

tigecycline

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14
Q

Glycylcyclines:

  • effective against (1) bacteria
  • (2) describe resistance
A

(tigecycline)
1- broad-spectrum: MDR Gram+, some Gram- and some anaerobes

2- little resistance — efflux pumps only in Proteus and Pseudomonas spp.

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15
Q

describe clinical use of glycylcyclines

A

(tigecycline)
Last Chance Antibiotic: inc risk of mortality seen when treating serious infections

-complicated skin, soft tissue, intra-abdominal infections

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16
Q

Glycylcyclines:

  • (1) route of administration
  • (2) describe distribution
  • (3) route of elimination
A

(tigecycline)
1- IV
2- excellent tissue and intracellular penetration
3- biliary / fecal elimination

17
Q

Glycylcyclines:

  • (1) AEs
  • (2) contraindications
A

1- well tolerated — similar AEs to tetracyclines: n/v/d

2- pregnancy, children <8y/o

18
Q

list the Aminoglycosides

A
  • amikacin
  • gentamicin
  • tobramycin
  • streptomycin
  • neomycin
19
Q

Aminoglycosides:

  • (1) is a unique feature in comparison to the activity of all other protein synthesis inhibitors
  • (2) describe general clinical use
A

1- bacetiocidal (all others are bacteriostatic)

2- mostly replaced by safer antibiotics — associated with serious toxicities

20
Q

describe the unique feature of pharmacodynamics with Aminoglycosides (hint: time v [drug])

A

Postantibiotic effect + Concentration-dependent killing = once daily dose

1) concentration dependent killing = more [drug] => better killing power VS. time-dependent where duration, not drug amount, affects killing power

21
Q

Aminoglycoside MOA:

  • (1) entry of (2) bacteria only
  • binds (ir-/reversibly) to (4) leading to inhibition of initiation complex, causing (5) and (6)
A

1- passively and actively (O2 dependent)
2- aerobic Gram- bacteria

3- irreversible (covalent bond)
4- 30S ribosomal subunit
5- misreading of mRNA
6- blockade of translocation

22
Q

describe the mechanisms of Aminoglycoside resistance

A

1) plasmid-associated synthesis of enzymes –> drug modification and inactivation via acetylation, phosphorylation, adenylation
2) dec drug accumulation
3) change in receptor protein on 30S ribosomal subunit (alteration or deletion via mutation)

23
Q

Aminoglycosides are the drug of choice for…..

A

Note- always empiric therapy and always in combination

*infective endocarditis w/ vancomycin

24
Q

Aminoglycoside Pharmacokinetics:

  • (1) route of administration
  • (2) describe distribution
  • (3) route of elimination
A

1- parenteral (once daily) —- except neomycin is topical

2- well-distributed everywhere: including CSF, bronchial secretions, *renal cortex and *inner ear

3- urine (reduce dose in renal insufficiency)

25
Q

Aminoglycoside AEs:

  • (1) are the common dangerous AEs
  • (2) are the main contraindications, explain
A

1- ototoxicity, nephrotoxicity

2:

  • Myasthenia Gravis – neuromuscular contraindication
  • Pregnancy (cat. D, unless benefits outweigh risks)
26
Q

Oral neomycin is used to treat (1); (2) are the alternative treatments for (1)

A

1- hepatic encephalopathy

2- lactulose, oral vancomycin, oral metronidazole, rifaximin

27
Q

describe the MOA of Lactulose (for hepatic encephalopathy)

A
  • non-absorbable disaccharide –> stays in GIT lumen
    1) degraded by intestinal bacteria => lactic acid + other organic acids
    2) gut lumen acidification
    3) favors NH4+ formation (over NH3)
    4) NH4+ is trapped in colon —> effectively reduces [NH3] in plasma
28
Q

Lactulose:

  • (1) non-MOA effects
  • (2) AEs (hint- related to (1))
A

1- prebiotic; osmotic laxative

2- osmotic diarrhea, flatulence, abdominal cramping

29
Q

list the macrolides

A

erythromycin
clarithromycin
azithromycin

30
Q

Macrolides:

  • (1) agents
  • bacterio-(static/cidal)
  • effective against (3) bacterial infections
A

1- erythromycin, clarithromycin, azithromycin

2- bacteriostatic —> bacteriocidal at high concentrations

3- Gram+

31
Q

Macrolides MOA:

  • (ir-reversibly) binds (2) subunit of (3) in order to block (4)
  • binding site / (2) is identical or closely related to binding site of (5) drugs
A

1- reversibly
2- 23S RNA
3- 50S ribosomal subunit
4- translocation

5- clindamycin, chloramphenicol

32
Q

describe mechanisms of resistance of Macrolides- discuss cross-resistance of agents

A

1) reduce membrane permeability // active efflux
2) esterase production => deactivation (enterobacteriaceae)
3) ribosomal binding site modification (chromosomal methylation or mutation)

  • complete cross-resistance between all macrolides
  • partial cross-resistance with clindamycin, streptogramins
33
Q

______ is the macrolide with the most narrow spectrum

A

erythromycin (< clarithromycin, azithromycin)

34
Q

Macrolides:

  • all are drugs of choice for (1) treatment
  • (2) is drug of choice for whooping cough
  • (3) are common empiric uses
  • substitute for (4)
A

1- atypical pneumonias (mycoplasma, chlamydia, legionella)

2- erythromycin for B. pertussis

3- CA-pneumonia, URIs, soft-tissue infections

4- penicillin in Pts w/ allergy

35
Q

______ is the therapy used for N. gonorrhea

A

combination:

  • erythromycin (macrolide)
  • ceftriaxone (3rd gen. cephalosporin)
36
Q

Macrolides Pharmacokinetics:

  • (1) has the lowest F
  • (2) is the only non-inhibitor of (3) => (4) as the main contraindication with agents that are not (2)
A

1- erythromycin

2- azithromycin
3- CYP P450 (erythromyin, clarithromycin are inhibitors)

4- statin use (+ if Pt is on many drugs)

37
Q

Macrolides AEs:

  • (1) GI effects, explain mechanism
  • (2) is a risk with erythromycin or azithromycin use
  • (3) is a risk with Pts with cardiac condition
  • (4) reactions / complications are rare
A

1- irritation via dec gut flora and Motiln receptor binding => pro-kinetic

2- hepatic abnormalities

3- QT prolongation

4- hypersensitivity/anaphylaxis, colitis (superinfection)

MNI (immuno pharm) (15 decks)

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