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IPFC 2 > Antibiotics: Pharmacology > Flashcards

Antibiotics: Pharmacology Flashcards

1
Q

Which are the beta lactams

A

penicillins, cephalosporins, carbapenems, and beta-lactamase inhibitors

** all have the lactam ring

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2
Q

MoA of beta lactams : cell wall

A

impact cell wall synthesis via inhibition of the transpeptidation reaction

  • Bind covalently and block PBP so that it can no longer remove terminal alanine; no cross linking occurring + peptidoglycan synthesis

**only kill cells that are actively growing

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3
Q

T or F: B lactams oral absorption is impaired by food

A

T - all except amoxicillin

— rest needed to be dosed 1-2 hours before or after a meal

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4
Q

Which beta lactams are acid stable

A

penicillin, amoxicillin, ampicillin and cloxacillin: can be given orally

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5
Q

Main SEs of Beta lactams

A

GI: N/V/D
Secondary opportunistic infections
- skin rash or hypersensitivity (cross reaction in class and across classes)

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6
Q

How does B lactam hypersensitivity occur

A

penicillin Ags are presented during metabolism to immune cells when bound to protein

  • recognized as non-self and mount response against
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7
Q

What is the main mech of B-lactam R

A

Beta-lactamase: destroys beta lactam ring —- and therefore Abx activity

  • included for penicllins, cephalosporins, carbapenems
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8
Q

2nd mech of R for beta lactams

A

modification of PBP (ex/ Strep. pneumo)
—- responsible for MRSA too

impaired penetration: gram - (more layers); efflux pumps (gram -)

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9
Q

B lactamase inhibitors include…

A

clavulanic acid and tazobactam

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10
Q

T or F: beta lactamase inhibitors have strong antibacterial activity on their own

A

F - they act as a suicide molecule and used in combo with beta lactam
—- distracts B-lactamase while beta lactam actually does its shit

** extends the penicillin activity too to include those with R because of beta lactamase production —- Beta lactam producing strands of S. aureus

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11
Q

What penicillins are b-lactamase inhibitors used in combo with

A

amoxicillin, ticarcillin, piperacilin

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12
Q

T or F: penicillin G is oral and V is IV

A

F - G is IV and V is oral

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13
Q

What are the anti-staphylococcal penicillins

A

Cloxacillin
- food impacts its absorption

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14
Q

What are the anti-pseudomonal penicillins

A

ticarcillin, piperacillin

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15
Q

What makes cephalosporins different than penicillins (structure)

A

beta lactam ring + 6C ring

penicillins: beta lactam ring + 5 C ring

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16
Q

T or F: penicillins tend to have a broader spectra than cephalosporins

A

F - cephalosporins is broader

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17
Q

T or F: all cephalosporins are prodrugs

A

F - some are prodrug esters

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18
Q

T or F: you can get cross sensitivity bw penicillins and cephalosporins

A

T - 1-5%

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19
Q

Special ADRs of cephalosporins

A

nephrotoxicity - high doses

disulfiram-like reactions: inhibit alcohol dehydrogenase so if drink get build up of acetaldehyde

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20
Q

What are the carbapenems

A

Include imipenem. meropenem and ertapenem

— same MoA: beta lactam

** imipenem is co-adminned with cola statin to prevent its breakdown in the kidney

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21
Q

SEs of carbapenems

A

N/V
seizures
cross reactivity with penicillins

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22
Q

T or F: Vanco is orally available

A

F - only IV unless treating GI shit

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23
Q

T or F: vancomycin targets the cell wall like Beta lactams

A

F - cell wall targeting but different MoA

binds to ala-ala terminal of peptidoglycan chain and prevents building

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24
Q

T or F: Vanco can’t penetrate gram - bacteria’s outer membrane

A

T == only impact gram +

25
Q

Unique SEs of Vanco

A

IV admin shit

toxicities associated with ear and kidney
- rare and not seen in humans ; just animal models

26
Q

Main mech of R to Vanco

A

mutation of target site (Ala-Ala) to Ala-Serine or Ala-lactate

27
Q

What is Fosfomycin

A

Non-beta lactam cell wall agent

  • inhibits the MurA enzyme that produces peptidoglycan by acting as a PEP analog

** inhibits earlier on the cell wall synthesis pathway

28
Q

ADRs of fosfomycin

A

Nausea, diarrhea, headache, neutropenia, angioedema

29
Q

What are the bacterial ribosomal parts

A

30S and 50S

human : 40S and 60S

  • different enough that targeting is relatively selective for B
30
Q

What is included in the protein synthesis inhibitors

A

Tetracyclines (doxy), marcolides, clindamycin

31
Q

What is the general structure of tetracyclines

A

4 ring system that is hydrophilic

32
Q

MoA of tetracyclines

A

inhibit protein synthesis by binding to the 30S subunit and blocking incoming tRNA

  • slow/stop translation
33
Q

T or F: Doxy is excreted in urine but also can undergo enterohepatic recycling

A

T

34
Q

Tetracycline SEs

A

GI
photosensitivity
liver toxicity: high doses
renal toxicity: Fanconi syndrome (expired tetracyclines)

Vestibular Rxn - minocycline

35
Q

When is it not safe to use tetracyclines

A

kids and pregnant people — chelate and bind to Ca
- accumulate in these areas and can impact bones and teeth

rxn related to dose: weight (not duration )

Doxy- only exception to this because decrease AFF to Ca

36
Q

Main Mech of R to Tetracyclines

A

Drug Efflux (pump shit out)

37
Q

MoA: Macrolides

A

protein synthesis inhibitors

  • bind reversible to 50S unit and inhibit transpeptidation and translocation
38
Q

What are the macrolides

A

azithromycin, clarithromycin and erthromycin

39
Q

Which of the macrolides is the best absorbed

A

Clarithromycin

  • Azithromycin is best on empty stomach and shouldn’t be taken with antacids
  • Erythromycin: acid labile and needs enteric coat
40
Q

What metabolizes the macrolides

A

CYP 3A4

41
Q

Which macrolides inhibit P450 enzymes

A

Clarith + Erythro but not Az

42
Q

SEs of Macrolides

A

GI: anorexia, N/V/D

fever, eosinophilia, rash

hepatotoxicity: erythromycin

QT prolongation

43
Q

Which macrolide has the highest risk of QT prolongation

A

E> C> A

** more risk when already have long QT interval

44
Q

T or F: there is one main mech of R for macrolides

A

F - they have just a shit ton

1) Reduce permeability (gram -) or active efflux (gram +)
2) destroy them via esterases
3) modification of ribosomal site (mutate target)

45
Q

What is Clindamycin? MoA

A

not a macrolide; acts like one but chemically different

  • MoA; binds to 50S and blocks (can have cross R bw macrolides and clindamycin; also will compete for same spot if coadmin)
46
Q

SEs of Clindamycin

A

N, D
skin rash
impaired LFT
neutropenia

47
Q

MoR for Clindamycin

A

Ribosomal access
- poor porin permeability (gram -)

no impact by efflux pumps in gram + — gram + can’t pump out*

decreased ribosomal binding: change target

48
Q

What are the DNA targeting ABx

A

FQ

49
Q

What are the FQs

A

Ciprofloxacin, norfloxacin, ofloxacin

Resp FQ: levofloxacin, moxifloxacin, gemifloxacin

— bactericidal

50
Q

FQ: MoA

A

block DNA synthesis
1) Inhibt DNA gyrase/topoisomerase II: DNA can’t uncoil and relax

2) Block Topoisomerase IV: replicated DNA does’t separate properly into cells during division

** expressed in humans too but relatively selective for B>H by 100-1000

51
Q

T or F: FQs are normally given orally

A

T

52
Q

FQ: ADRs

A

GI
photosensitivity
headache, dizzy, drowsiness, insomnia
skin rash, abnormal LFTs
QT prolongation
cartilage and tendon damage: only seen in animal models
—— why not used in those younger 18 years or pregnant people

53
Q

Main MoR for FQ

A

mutations in binding region of target enzyme
- mutation of gyrA subunit of DNA gyrase

others: change permeability, expression of proteins that protect DNA gyrase from FQ

54
Q

MoA: Metronidazole

A

Nitro group on Abx is metabolized into toxic radical in anaerobic bacteria
— ferrodoxins reduce nitro group to radical to react with DNA and cause damage

** only impacted by aerobic bacteria, inhibited by O2 levels that are high

** once done its shit, gets regenerated and can repeat

55
Q

DF for Metronidazole

A

IV, oral or suppository

56
Q

SEs of Metronidazole

A

headache
N/V/D
dry mouth
disulfiram like effects
increased prothrombin time

Rare (CNS): ataxia and paresthesias
- associated with duration of therapy

57
Q

Main MoR: Metronidazole

A

mutation that impairs production of nitro anion

  • decrease O2 scavenging ability (can’t get rid of O2 as well in bacteria)
  • decreased levels of ferredoxin
58
Q

What is Fidoxamicin? MoA

A

Thicc boi that works against gram + and anaerobic bacteria

  • binds to sigma subunit of RNA poly - inhibit it and transcription

** used for C. difficile

IPFC 2 (5 decks)

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