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BIIC Cancers and Pharmo > Antimicrobials III: Protein Synthesis Inhibitors > Flashcards

Antimicrobials III: Protein Synthesis Inhibitors Flashcards

1
Q

DNA/RNA Synthesis Inhibitors

A

Indirect: folate antagonists
Direct: Quinolones and other drugs

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2
Q

What do protein synthesis inhibitors target?

A

bacterial ribosome–> prevents growth

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3
Q

Most are bacteriostatic

A

some are bactericidal

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4
Q

What are 3 issues with protein synthesis inhibitors?

A
  1. need access to ribosomes
  2. mode of resistance is antibiotic efflux and reduced uptake by bacteria
  3. bacterial-produced enzymatic deactivation
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5
Q

Bacterial Protein Synthesis Step 1

A

charged tRNA unit delivers an amino acid to acceptor site on 70S ribosome

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6
Q

Bacterial Protein Synthesis Step 2

A

tRNA at the donor site, with an amino acid chain binds the growing chain to a new amino acid

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7
Q

Bacterial Protein Synthesis Step 3

A

uncharged tRNA left at donor site is released

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8
Q

Bacterial Protein Synthesis Step 4

A

new amino acid chain w/ tRNA is translocated to peptidyl side

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9
Q

Tetracyclines and Aminoglycosides affect which step in bacterial protein synthesis?

A

Step 1 - bind the 30S subunit and prevent the binding of incoming charged tRNA unit

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10
Q

Macrolides, Clindamycin, and Chloramphenicol affect which step in bacterial protein synthesis?

A

Step 2 - bind tot he 50S subunit and block peptide bond formation

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11
Q

Target 30S subunit (2)

A
  1. aminoglycosides
    - gentamicin, amikacin, tobramycin, neomycin, streptomycin
  2. tetracyclines
    - doxycycline, tetracycline, tigecycline(IV), minocycline
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12
Q

Target 50S subunit (5)

A
  1. lincosamides
    - clindamycin
  2. Macrolides
    - azithromycin, clarithromycin, erythromycin
  3. Streptogramins
    - quinupristin/dalfopristin(IV)
  4. Oxazolidinones
    - linezolid
  5. Amphenicols
    - chloramphenicol
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13
Q

Aminoglycosides (ANGST) MOA

A

ANGST: amikacin, neomycin, gentamicin, streptomycin, tobramycin

  • broad-spectrum
  • bind to 30S subunit = prevent initiation of protein synthesis–> causing misreading of RNA
  • bacteriostatic
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14
Q

Aminoglycosides are primarily used against gram ________

A

negative bacilli–> E. coli, Klebsiella pneumoniae, P. aeruginosa

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15
Q

Aminoglycosides are toxic to the ______ and ______.

A

kidney and inner ear - binds to renal tissue and may reach toxic concentrations in kidney and inner ear (neomycin and streptomycin)

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16
Q

How are aminoglycosides administered? Half-life?

A

parenterally –> IV, IM

2-3hrs

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17
Q

Aminoglycosides: excretion

A

excreted unchanged in the urine

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18
Q

Aminoglycosides: ADRs

A
  • ototoxicity: balance/vertigo, deafness
  • neurotoxicity: blockade of presynaptic release of ACh at NMJ and postsynaptic blockade–> weakness and respiratory depression
  • hypersensitivity rxns
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19
Q

Aminoglycosides: Contraindications

A

myasthenia gravis; also avoid w/ pregnancy

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20
Q

Tetracyclines: Names and MOA

A
  • doxycycline, tigecycline(IV), minocycline, tetracycline
  • broad-spectrum against gram +/-
  • bind reversibly to 30 S subunit –> preventing tRNA from binding to the mRNA-ribosome complex
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21
Q

How does resistance to tetracyclines occur? (3)

A
  1. acquire efflux pathways
  2. produce protein blocking it from binding to ribosome
  3. enzymatically inactivate the drug
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22
Q

Tetracyclines: Spectrum

A

activity MSSA and MRSA

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23
Q

Tetracyclines: Don’t Take With?

A

Antacids and dairy–> antibiotics form chelates with divalent metal ions

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24
Q

Tetracyclines: Metabolism and Excretion

A
  • hepatically

- feces and urine

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25
Q

Tetracyclines: DDIs

A

digoxin, CYP substrates(warfarin) or inducers(carbamazepine, alcohol, barbiturates, etc)

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26
Q

Tetracyclines are ______% bound by serum proteins

A

40-80%

27
Q

Tetracyclines: ADRs

A
  • hypersensitivity = rare
  • phototoxicity
  • GI: nausea, vomiting, diarrhea
  • bind to newly formed bone or developing teeth
  • hepatotoxicity
  • nephrotoxicity
  • dizziness, vertigo, tinnitus
28
Q

Tetracyclines: Contraindications

A
  • children under 8
  • pregnancy
  • pt with preexisting liver disease
29
Q

Macrolides: MOA and Names

A
  • azithromycin and erythromycin = PO and IV
  • clarithromycin = PO
  • bind reversibly to 50S subunit and inhibits translocation of the growing peptide/ may also interfere with transpeptidation
  • bacteriostatic
30
Q

Macrolides: Spectrum

A
  • broad-spectrum
  • effective against many gram +/- organisms susceptible to penicillin G
  • good alternative if pt has penicillin allergy
31
Q

Macrolides: Resistance (3)

A
  1. efflux pumps
  2. decreased affinity of 50S subunit for antibiotic = gram+
  3. enzymatic degradation = gram-
32
Q

Macrolides: ADR (3)

A
  1. ototoxicity
  2. cardiotoxicity
  3. many DDIs w/ agents for competing for CYP450 metabolism
33
Q

Streptogramins: names

A

quinupristin and dalfopristin

34
Q

Streptogramins: MOA

A
  • derived from streptomyces pristinaespiralis
  • both bind to 50S at different sights
  • Q = prevents elongation/release of incomplete peptide chains
  • D = disrupts elongation/interferes w/ addition of new peptides onto chain
35
Q

Streptogramins: Spectrum

A
  • bactericidal = gram + cocci
  • bacteriostatic = Enterococcus faecium and VRE strains
  • also for atypical pneumonia
36
Q

Streptogramins: Resistance (2)

A
  • enzymatic deactivation

- efflux pump

37
Q

Streptogramins: Pharmacokinetics

A

hepatically metabolized and excreted in feces –> good for those w/ MRSA and renal problems

38
Q

Streptogramins: ADRs (2)

A
  1. hyperbilirubinemia

2. metabolism by CYP3A4 leads to DDIs w/ inducers/inhibitors

39
Q

Oxazolidinones: name

A

linezolid

40
Q

Oxazolidinones: MOA

A

binds to the 23S ribosomal RNA of the 50S inhibiting the formation of the 70 S complex

  • bacteriostatic
  • bactericidal against streptococci
41
Q

Oxazolidinones: Spectrum

A
  • drug-resistant, aerobic, gram +

- alternative to daptomycin for Vancomycin-resistant enterococci (VRE)

42
Q

Oxazolidinones: Resistance (1)

A

reduced binding to target site

43
Q

Oxazolidinones: Pharmacokinetics

A

excreted by renally and biliary

44
Q

Oxazolidinones: ADRs/DDIs (3)

A
  1. neurotoxicity = irreversible peripheral neuropathy and optic neuritis = blindness
  2. HTN
  3. serotonin syndrome
45
Q

Chloramphenicol: Spectrum

A
  • broad-spectrum

- aerobic and anaerobic EXCEPT P. aeruginosa

46
Q

Chloramphenicol: Major Toxicity

A

high circulating chloramphenicol levels can lead to mitochondrial ribosomes to also be affected leading to BONE MARROW TOXICITY

47
Q

Chloramphenicol: ADRs (2)

A
  1. bone marrow depression/aplastic anemia (can be fatal)

2. Gray baby syndrome (often fatal): babies can’t conjugate drug

48
Q

Lincosamides: name

A

clindamycin

49
Q

Lincosamides: Spectrum

A
  • bacteriostatic against gram +

- MRSA, streptococcus, anerobic bacteria

50
Q

Lincosamides: Pharmacokinetics

A

100% orally bioavailable

51
Q

Lincosamides: ADR

A

high risk of C. difficile superinfection

52
Q

DNA/RNA Synthesis Inhibitors: 2 Types

A

Indirect: folate antagonists
Direct: Quinolones and other drugs

53
Q

Fluoroquinolones: Names

A

ciprofloxacin, levofloxacin, moxifloxacin

54
Q

Fluoroquinolones: MOA

A

inhibit DNA gyrase and topoisomerases in inhibition of DNA replication

55
Q

Fluoroquinolones: Spectrum

A

B. anthracis, Mycobacterium sp., Listeria sp., Chlamydia sp., UTIs, anaerobic, resistant respiratory infections, GI infections

56
Q

Fluoroquinolones: Pharmacokinetics

A
  • well absorbed orally
  • divalent cations impair absorption
  • renal elimination
57
Q

Fluoroquinolones: ADRs (4)

A
  1. discontinue if: nausea, vomiting, headache, dizziness
  2. phototoxicity
  3. cardiotoxicity - prolong QT interval
  4. inhibit CYP450 - 1A2 and 3A4
58
Q

Folic Acid/Folate Antagonists: Name

A

cotrimoxazole

59
Q

Folic Acid/Folate Antagonists: Spectrum

A
  • broad and bacteriostatic

- gram + cocci and gram - bacilli, actinomycetes, chlamydia and protozoa, UTIs

60
Q

Folic Acid/Folate Antagonists: MOA

A

competitive inhibitor of folic acid synthesis

- inhibits dihydrofolate reductase and dihydropteroate synthesis

61
Q

Sulfonamides: Pharmacokinetics

A
  • well absorbed orally

- bound to serum albumin and widely distribute throughout body tissues including CSF and fetal tissues

62
Q

Sulfonamides: ADRs (3)

A
  1. nephrotoxicity = crystalluria
  2. hypersensitivity = rashes, angioedema, Stevens-Johnson syndrome
  3. Kernicterus = hyperbilirubinemia-associated brain damage in newborns
63
Q

Cotrimoxazole/TMP-SMZ: Spectrum

A
  • fixed dose

- UTIs, prophylactic and resolving certain opportunistic infections in AIDS, S. typhii

BIIC Cancers and Pharmo (10 decks)

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