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

Antimicrobials III: Protein Synthesis Inhibitors Flashcards

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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
Tetracyclines: DDIs
digoxin, CYP substrates(warfarin) or inducers(carbamazepine, alcohol, barbiturates, etc)
26
Tetracyclines are ______% bound by serum proteins
40-80%
27
Tetracyclines: ADRs
- hypersensitivity = rare - phototoxicity - GI: nausea, vomiting, diarrhea - bind to newly formed bone or developing teeth - hepatotoxicity - nephrotoxicity - dizziness, vertigo, tinnitus
28
Tetracyclines: Contraindications
- children under 8 - pregnancy - pt with preexisting liver disease
29
Macrolides: MOA and Names
- 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
Macrolides: Spectrum
- broad-spectrum - effective against many gram +/- organisms susceptible to penicillin G - good alternative if pt has penicillin allergy
31
Macrolides: Resistance (3)
1. efflux pumps 2. decreased affinity of 50S subunit for antibiotic = gram+ 3. enzymatic degradation = gram-
32
Macrolides: ADR (3)
1. ototoxicity 2. cardiotoxicity 3. many DDIs w/ agents for competing for CYP450 metabolism
33
Streptogramins: names
quinupristin and dalfopristin
34
Streptogramins: MOA
- 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
Streptogramins: Spectrum
- bactericidal = gram + cocci - bacteriostatic = Enterococcus faecium and VRE strains - also for atypical pneumonia
36
Streptogramins: Resistance (2)
- enzymatic deactivation | - efflux pump
37
Streptogramins: Pharmacokinetics
hepatically metabolized and excreted in feces --> good for those w/ MRSA and renal problems
38
Streptogramins: ADRs (2)
1. hyperbilirubinemia | 2. metabolism by CYP3A4 leads to DDIs w/ inducers/inhibitors
39
Oxazolidinones: name
linezolid
40
Oxazolidinones: MOA
binds to the 23S ribosomal RNA of the 50S inhibiting the formation of the 70 S complex - bacteriostatic - bactericidal against streptococci
41
Oxazolidinones: Spectrum
- drug-resistant, aerobic, gram + | - alternative to daptomycin for Vancomycin-resistant enterococci (VRE)
42
Oxazolidinones: Resistance (1)
reduced binding to target site
43
Oxazolidinones: Pharmacokinetics
excreted by renally and biliary
44
Oxazolidinones: ADRs/DDIs (3)
1. neurotoxicity = irreversible peripheral neuropathy and optic neuritis = blindness 2. HTN 3. serotonin syndrome
45
Chloramphenicol: Spectrum
- broad-spectrum | - aerobic and anaerobic EXCEPT P. aeruginosa
46
Chloramphenicol: Major Toxicity
high circulating chloramphenicol levels can lead to mitochondrial ribosomes to also be affected leading to BONE MARROW TOXICITY
47
Chloramphenicol: ADRs (2)
1. bone marrow depression/aplastic anemia (can be fatal) | 2. Gray baby syndrome (often fatal): babies can't conjugate drug
48
Lincosamides: name
clindamycin
49
Lincosamides: Spectrum
- bacteriostatic against gram + | - MRSA, streptococcus, anerobic bacteria
50
Lincosamides: Pharmacokinetics
100% orally bioavailable
51
Lincosamides: ADR
high risk of C. difficile superinfection
52
DNA/RNA Synthesis Inhibitors: 2 Types
Indirect: folate antagonists Direct: Quinolones and other drugs
53
Fluoroquinolones: Names
ciprofloxacin, levofloxacin, moxifloxacin
54
Fluoroquinolones: MOA
inhibit DNA gyrase and topoisomerases in inhibition of DNA replication
55
Fluoroquinolones: Spectrum
B. anthracis, Mycobacterium sp., Listeria sp., Chlamydia sp., UTIs, anaerobic, resistant respiratory infections, GI infections
56
Fluoroquinolones: Pharmacokinetics
- well absorbed orally - divalent cations impair absorption - renal elimination
57
Fluoroquinolones: ADRs (4)
1. discontinue if: nausea, vomiting, headache, dizziness 2. phototoxicity 3. cardiotoxicity - prolong QT interval 4. inhibit CYP450 - 1A2 and 3A4
58
Folic Acid/Folate Antagonists: Name
cotrimoxazole
59
Folic Acid/Folate Antagonists: Spectrum
- broad and bacteriostatic | - gram + cocci and gram - bacilli, actinomycetes, chlamydia and protozoa, UTIs
60
Folic Acid/Folate Antagonists: MOA
competitive inhibitor of folic acid synthesis | - inhibits dihydrofolate reductase and dihydropteroate synthesis
61
Sulfonamides: Pharmacokinetics
- well absorbed orally | - bound to serum albumin and widely distribute throughout body tissues including CSF and fetal tissues
62
Sulfonamides: ADRs (3)
1. nephrotoxicity = crystalluria 2. hypersensitivity = rashes, angioedema, Stevens-Johnson syndrome 3. Kernicterus = hyperbilirubinemia-associated brain damage in newborns
63
Cotrimoxazole/TMP-SMZ: Spectrum
- fixed dose | - UTIs, prophylactic and resolving certain opportunistic infections in AIDS, S. typhii

BIIC Cancers and Pharmo (10 decks)

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