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Pharm Exam 1 > Abx 2 > Flashcards

Abx 2 Flashcards

1
Q

What are the three families of drugs classified as “beta lactams”?

A
  1. Penicillins
  2. Cephalosporins
  3. Carbapenems
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2
Q

Are beta lactams bactericidal or bacteriostatic?

A

-bacteriCIDAL

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3
Q

By what mechanism do beta lactam antibiotics work?

A

-Cell wall formation disruptor

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4
Q

What is the specific target site that to which beta lactams attach in order to kill bacteria?

A
  • PBP site
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5
Q

How long after the development of penicillin as an antibiotic did resistance to the drug appear?

A
  • 10 years
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6
Q

What is the role of peptidoglycans and transpeptidase in the formation of bacterial cell walls, and how do beta lactams alter this?

A
  • PG = backbone of cell wall lattice
  • transpeptidase (AKA penicillin binding protein PBP) = create peptide links to stabilize PG backbone

*Beta lactams inhibit Transpeptidase

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7
Q

Are penicillins considered time-dependent or concentration-dependent? Why?

A
  • Time dependent
    • must constantly be present at infection site
    • therefore, dose 3-4x’s per day
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8
Q

Inhibition of different PBPs produces what changes in the bacterial cell (not specific ones, just what are the different effects they might have)?

A
  • rapid bacterial cell lysis
  • slower bactericidal
  • long strands
    • which PBP it binds determines degree of bactericidal-ness
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9
Q

What is the mechanism by which some Staphylococcus aureus bacteria are resistant to methicillin?

A
  • altered the shape of the PBP-1

- can NOT bind to PBP-2a

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10
Q

2 characteristics of Gram negative bacteria that are different from Gram positive bacteria, and that contribute to Gram negative resistance to beta lactam antibiotics.

A
  • Thick outer (lipid) membrane

- Small porins

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11
Q

Do beta lactamase enzymes destroy all beta lactam drugs?

A
  • Penicillinases
  • Cephalosporinases
  • or can destroy both
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12
Q

Due to Staphylococcal aureus beta lactamase, which drugs are effective/ineffective?

????

A
  • most penicillins are NOT effective
  • Staph beta lactamase does NOT affect CEPHALOSPORINS (nor cross resistance)
  • naturally resistant to Beta lactamase = Oxa-, cloxa-, dicloxacillin
  • Clavulanic acid
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13
Q

Generally, how are the Gram negative bacterial beta lactamase enzymes different from Staphylococcal beta lactamase?

Do they destroy just penicillins?

Can clavulanic acid block Gram negative’s beta lactamase enzyme?

A
  • destroy a wider range of β lactam drugs
    - penicillinases & cephalosporinases in the periplasm!

-Clavulanic acid added to penicillins can counter effect

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14
Q

What is the mechanism by which E. coli is resistant to most beta lactams?

A
  • Beta lactamases right inside the Outer membrane
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15
Q

Why is clavulanic acid considered to be a suicide inhibitor of beta lactamase?

What is the other suicide inhibitor beside clavulanic acid?

A
  • Has Beta lactam ring
    - NO anitmicrobial activity
    - inactivates Beta lactamase

-Sulbactam

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16
Q

What are the 4 groups of penicillins?

A
  1. Natural Penicillins
  2. Aminopenicillins
  3. Antistaphyloccal penicillins
  4. Extended spectrum penicillin
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17
Q

Which penicillins are “natural” penicillins?

A
  • Pen G
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18
Q

Which penicillins are aminopenicillins?

A
  1. amoxi-cillin

2. ampi-cillin

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19
Q

Which penicillins are naturally resistant to Staphylococcal beta lactamase?

A
  1. oxa-cillin
  2. cloxa-cillin
  3. dicloxa-cillin
  4. methi-cillin
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20
Q

Which penicillins are considered to be “extended spectrum” penicillins?

A
  1. pipera-cillin
  2. ticar-cillin
  3. carbeni-cilin

**Big Guns— “I can’t afford drugs”

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21
Q

Is penicillin G good against:

  • Pseudomonas?
  • Gram positives?
  • Streptococci?
  • All Staphylococci?
  • Gram negatives?
A

Narrow spectrum

  • most Strep
  • non-penicillinase Staph
  • Gram positives

NOT

  • Gram Neg
  • Pseduomonas
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22
Q

Why isn’t penicillin G available in tablets?

A
  • acid destroys the molecule

* *IV only**

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23
Q

Why are penicillins in general very good for use in urinary tract infections?

A

-ACTIVELY secreted INTACT into PCT –> highly concentrated in the urine

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24
Q

How is penicillin G dosed that is different from the other beta lactam antibiotics?

A

-Units/kg

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25
Q

Do penicillins have a long half life or a short half life? How does this translate into frequency of dosage administration? How does that translate into client compliance with medication administration?

A
  • ????
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26
Q

What are the three types of penicillin G?

A
  1. Sodium/potassium Pen G–short half lives
  2. Procaine Pen G
  3. Benzathine Pen G
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27
Q

What is the purpose of adding a sodium or potassium molecule to penicillin?

A

-form water soluble to be given IV

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28
Q

What is the purpose of procaine or benzathine added to penicillin?

How long do each last?

A
  • makes it insoluble in H2O
  • -> slows release of penicillin from the injection site when given SQ or IM
Procaine = 12-24 hrs
Benzathine = 3-5 days
29
Q

Why can’t procaine or benzathine penicillin be given IV?

A
  • insolubility –> plugs up capillaries
30
Q

What is the disadvantage of using a benzathine penicillin product versus just “plain” penicillin G?

A
  • greater variable plasma drug concentrations at any given time
31
Q

2 Aminopenicillins

A
  1. Amoxicillin

2. Ampicillin

32
Q

Why is amoxicillin advantageous over penicillin G for dispensing to clients to use at home?

A

-not inactivated by acid –> tablet form (PO)

33
Q

How are aminopenicillins for activating against:

  • Gram positives?
  • Gram negatives?
  • Susceptibility to beta lactamase?
A
  • same spectrum as Pen G
  • *PLUS** some Gram Neg

-Very susceptible to Beta lactamases
(Clavulanic acid or sulbactam added)

34
Q

What is the purpose of adding trihydrate to amoxicillin or ampicillin?

A

-to produce a slow-release suspension

35
Q

What is sulbactam used for?

A
  • to overcome β lactamase
36
Q

4 ‘beta lactamase stable’ or antistaphylococcal penicillins.

A
  1. Oxacillin
  2. Cloxacillin
  3. Dicloxacillin
  4. Methicillin
37
Q

“beta lactamase stable” effective more than penicillin G or aminopenicillins against which bacteria?

A

-Staphylococcus

38
Q

Are ‘beta lactamase stable’ penicillins more effective against Gram negatives than penicillin G or aminopenicillins?

A

-not penetrate outer membrane of Gr –

**Narrow spec

39
Q

For what purpose are antistaphylococcal antibiotics used in veterinary medicine?

A
  • Staph and Streptococcus mastitis in cattle

- cloxacillin

40
Q

3 extended spectrum penicillins

A
  1. Ticarcillin
  2. Piperacillin
  3. Carbenacillin
41
Q

Which penicillin might be effective against Pseudomonas bacteria?

A
  • extended spectrum penicillins
    • Readily penetrates outer membrane Gram NEG
      - including Pseudomonas
42
Q

Are extended spectrum penicillins any better against Gram negatives than aminopenicillins?

A

-Readily penetrates outer membrane

Gram negative

43
Q

Are extended spectrum penicillins any better against beta lactamase than aminopenicillins?

A

-susceptible to β lactamase
– clavulanic acid is added
(Timentin = ticarcillin + CA)

44
Q

With what other antibiotic are ticarcillin, piperacillin, and carbenacillin used to produce a synergistic antimicrobial effect?

A

-aminoglycosides

45
Q

For what purpose are extended spectrum penicillins most commonly used in veterinary medicine?

A

-resistant Gram NEG bacterial infections (small animals)

46
Q

Why do we care that penicillins are ionized at most body pH?

A

– less ability to diffuse across cell

- can’t cross BBB, eye, prostate

47
Q

Given the mechanism by which beta lactams work, why is the short half-life of penicillins a disadvantage?

A
  • drugs need to be on site continuously to be effective

- Need frequent re-dosing

48
Q

What is the most severe reaction to penicillin drugs? Does it occur more with injectable or oral formulations?

A

Allergy: Second exposure can result in severe systemic anaphylaxis and death
**associated w/ injectable form! **

-not nephrotoxic, not hepatotoxic

49
Q

How does a mild hypersensitivity rxn appear in dogs and cats? Why is it important to recognize the mild hypersensitivity reaction to these drugs?

A
  • swollen face
  • hives
  • *first exposure –> sensitizes immune system
  • *second exposure –> severe systemic anaphylaxis and death
50
Q

Why are oral penicillins not to be used in many lab animal species (Guinea pig, hamster, gerbil, rabbit)?

A
  • Rodents = very susceptible to killing Gram POS gut flora –> clostridium overgrowth –> fatal
51
Q

What is the issue with Procaine Pen G and its use in race horses?

A
  • local anesthetic properties

* *Regulated – test positive for as long as 2 wks

52
Q

What does it mean that cephalosporins (and other beta lactams) are “time dependent” drugs?

A

-Must be at site of infection at the time of division

53
Q

How do 1st gen differ from 3rd gen cephalosporins as far as their overall spectrum of activity?

A

1st gen

  • Gram +
  • β lactamase Staphylococcus (better than amino penicillin)

3rd gen

  • Gram - (Pseudomonas)
  • LESS effective for Gram +
54
Q

What does it mean that some cephalosporins are considered “empirical treatment options”?

A

-

55
Q

Does beta lactamase affect cephalosporins more or penicillins more commonly?

A
  • more effective than aminopenicillins

- resistance forms similarly (beta lactamases)

56
Q

Which is more effective against Staphylococcal beta lactamase:
1st generation cephalosporin
or amoxicillin?

A

-1st gen Cephalosporins

57
Q

FOUR 1st generation cephalosporins

A
  1. Cefadroxil
  2. Cephapirin
  3. Cephalexin
  4. Cefazolin
58
Q

THREE 3rd generation cephalosporins

A
  1. Cefpodoxime = Simplicef®
  2. Ceftiofur
  3. Cefovecin = Covenia®
59
Q

What dosage form (tablets, injectable, ointments, etc.) do most 3rd generation cephalosporins come in?
Which FDA-veterinary-medical-use-approved cephalosporin is the exception to this? trade name? administered?

A

-injectables

Exception: cefpodoxime (Simplicef®) = PO

60
Q

What species of bacteria are 3rd generation cephalosporins worse at than penicillin G or aminopenicillins?

A

-Gram positive (Staph/Strep)

61
Q

How long does Convenia® supposedly last?

For what condition is it used to treat? dogs and cats? administered?

A
  • 14 days (half life = 5-7days!)
  • Tx Dog/cat PyoDerma
  • injection
62
Q

What does it mean that beta-lactams in general have a “high therapeutic index”?

A

-concentrations widely separated from toxic concentrations

63
Q

What is the most severe adverse reaction with cephalosporins?

A
  • Allergy or Hypersensitivity, like penicillin
64
Q

Is there cross-hypersensitivity in patients between penicillin and cephalosporins?

A

-4X increased risk for hypersensitivity if know to be allergic to penicillin

65
Q

What carbapenem (“penem”) drug has been used in veterinary medicine?

A

-Imipenem (Primaxin®)

66
Q

What is the specific indication (use) for imipenem in veterinary medicine?

A
  • serious infections (Gram Neg Sepsis)

* * broadest spectrum of Beta lactams!

67
Q

What is the role of cilastin with imipenem use and why does it protect the animal? What happens if cilastin is not used with imipenem?

A
  • inhibits enzymes in renal tubules

- –> prevents nephrotoxicity

68
Q

Why is it supposedly important that imipenem is a faster bactericidal drug than the other beta lactam drugs?

A

-Helpful for killing Gram Neg bacteria in blood, releasing harmful endotoxins

Pharm Exam 1 (6 decks)

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