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Flashcards in Pharm Unit 3 Deck (40)
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1
Q

Aminoglycoside Mechanism of Action

A

Irreversibly bind and inhibit 30S subunit - block bacterial protein synthesis

2
Q

Aminoglycoside MOR

A
  • Synthesis of aminoglycoside modifying enzymes
  • Altered aminoglycoside uptake (loss of porin channel, efflux pump)
  • Change in binding site at ribosome/target modification
3
Q

Gentamicin

A

Aminoglycoside
Good gram negative activity (enterobacteriaceae) and gram positive activity (synergistic with cell wall agent for S. aureus, S. pyogenes, Veridans strep, Enterococcus)

4
Q

Tobramycin

A

Similar to gentamycin but more active against pseudomonas

5
Q

Amikacin

A

More active against nosocomial gram negative organisms (tobra still more active against pseudomonas)
Has activity against mycobacteria and nocardia

6
Q

Streptomycin

A

Mainly used to treat gram positive infections in combination with cell wall agent
Has activity against mycobacteria

7
Q

AGs used to treat gram negatives

A

Gentamycin, Tobramycin, Amikacin

8
Q

AGs used to treat gram positives

A

Gentamycin, Streptomycin

9
Q

AGs used to treat mycobacteria

A

Amikacin, Streptomcyin

10
Q

Aminoglycoside Pharmacokinetics

A

Administered primarily IV - poor oral absorption
Poor penetration of CNS - high concentration in urine
Concentration-dependent killing - PAE ranges from 0.5 to 7.5 hours
Most are renally eliminated
Extended dosing interval can help reduce ototoxicity (irreversible) and nephrotoxicity (reversible)

11
Q

Cephalosporin MOA

A

Binds PBPs - interfere with bacterial cell wall synthesis (prevent transamination step)
Bactericidal

12
Q

Cephalosporin MOR

A

1) Production of beta lactamase enzymes
2) Alterations in PBPs leading to decreased affinity
3) Alteration of outer membrane leading to decreased penetration to PBPs

13
Q

First generation cephalosporins

A

Best activity against gram positives, good activity against gram negatives (PEK)

14
Q

Second generation cephalosporins

A

More active against gram negative aerobes (HENPEK)

Cephamycins - only cephalosporins to have activity against anaerobes (B. fragilis)

15
Q

Third generation cephalosporins

A

More active against gram negative aerobes (HENPECKSSS)
Ceftriaxone, cefotaxime - best activity against gram positive aerobes, including pen-resistant S. pneumonia
Ceftazidime has pseudomonas activity

16
Q

Fourth generation cephalosporins

A

Even more activity against gram negatives
Includes activity against pseudomonas and beta lactamase producing enterobacter species
Only cefepime currently available

17
Q

Fifth generation cephalosporins

A

Activity against respiratory pathogens (H flu, strep pneumo, Moraxella, staph aureus, MRSA)
Only ceftaroline available

18
Q

Cephalosporin Pharmacokinetics

A

Oral forms well absorbed but food decreases absorption
*CSF concentrations only achieved with IV cefuroxime, 3rd and 4th generation cephalosporins
Eliminated by kidneys - adjust dose in RI
Short half life except ceftriaxone (8 hours; all others 2 hours)

19
Q

Cephalosporin Adverse Effects

A

Hypersensitivity - cross reactivity with penicillins
Hypoprothrombinemia in agents that have MTT side chain
Ethanol intolerance
Leukopenia and thrombocytopenia
Precipitation of ceftriaxone if given with IV calcium

20
Q

Carbapenem MOA

A

Inhibit cell wall synthesis - binds to and inhibits PBP-2; time-dependent killing
*Most broad spectrum of all agents available - has activity against gram positive, gram negative aerobes and anaerobes.

21
Q

Carbapenem MOR

A

1) Beta lactamase production
2) Decreased permeability
3) Alterations in PBPs

22
Q

Carbapenem Spectrum of Activity

A

Most broad spectrum of activity of all agents available
Imipenem and doripenem - gram positive activity
Doripenem and meropenem - gram negative activity
Ertapenem does not have activity against pseudomonas aeruginosa

23
Q

Carbapenem Pharmacokinetics

A

Meropenem has best CSF penetration
All eliminated by kidney - dose adjustment with RI
Imipenem has to be given with cilastatin - DHP inibitor, prevents metabolism

24
Q

Carbapenem Clinical Uses

A

Empiric therapy for hospital acquired infections
Polymicrobial infections
Do not use ertapenem when suspecting pseudomonas infection

25
Q

Carbapenem Adverse Effects

A

Hypersensitivity - 5-15% cross reactivity with penicillins
GI effects
Increased risk for seizures

26
Q

Aztreonam MOA

A

Inhibits cell wall synthesis by binding and inhibiting PBP3 - only has activity against gram negative aerobes

27
Q

Aztreonam Pharmacokinetics

A

Only available IV
Penetrates CSF in presence of inflamed meninges
Eliminated by kidneys - dose adjustment in RI
Used for typical gram negative infections - UTIs, RTIs, meningitis, bacteremia, SSTIs

28
Q

Aztreonam Adverse Effects

A

GI
Hypersensitivity
No cross reactivity with penicillins - can be used in penicillin-allergic patients

29
Q

Vancomycin MOA

A

Inhibits bacterial cell wall synthesis by inhibiting D-ala-D-ala; prevents elongation and crosslinking
Exhibits time-dependent bactericidal activity

30
Q

Vancomycin MOR

A

1) Modification of D-ala-D-ala binding site of PPG

2) VISA - thickened cell wall

31
Q

Vancomycin Spectrum of Activity

A

Effective against intrinsically resistant gram positive organisms

  • MRSA
  • MSSA
  • Strep pneumo, PRSP
  • C. difficile if given orally
32
Q

Vancomycin Pharmacokinetics

A

Time-dependent bactericidal activity
IV for systemic infection - orally for C. diff infection
Poorly absorbed in GI tract
Draw peak 1 hour after infusion, draw trough 30 minutes before infusion
Eliminated by kidney - can lead to long half life if RI present; not removed by dialysis

33
Q

Vancomycin Adverse Effects

A

Red Man Syndrome - due to histamine release caused by very rapid infusion rates
Nephrotoxicity/Ototoxicity - uncommon with vancomycin monotherapy - more common in used in combination
Can also lead to rash, neutropenia, thrombocytopenia, interstitial nephritis

34
Q

Linezolid MOA

A

Binds 50S subunit - inhibits bacterial protein synthesis (bacteriostatic)

35
Q

Linezolid Spectrum of Activity

A

Resistant gram positive organisms

- MRSA, VISA, PRSP, VRE

36
Q

Linezolid Pharmacokinetics

A

100% bioavailable, 30% CSF penetration

Eliminated renally and nonrenally - dose adjustment not necessary; removed by dialysis

37
Q

Linezolid side effects

A

Serotonin syndrome when used with SSRIs/MAOIs
Enhanced pressor effect with adrenergic/serotonergic agents
Lactic acidosis
Peripheral neuropathy
Thrombocytopenia/anemia

38
Q

Daptomycin MOA

A

Depolarizes bacterial membrane - leads to decreased protein, DNA, RNA synthesis
Exhibits concentration dependent killing

39
Q

Daptomycin Pharmacokinetics

A

Only administered IV
90% protein bound
Primarily eliminated renally - dose adjustment necessary in RI
Should not be used for treatment of pneumonia

40
Q

Daptomycin Adverse Effects

A

GI
Headache
Myopathy and CPK elevation