Beta Lactams Flashcards

1
Q

What is the target of beta-lactams?

A

Transpeptidase enzyme

It alters the action of transpeptidase, resulting in defective cell wall synthesis. Cell wall is unosmotically active and cell dies.

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2
Q

Microbial resistance to beta-lactams

A
  1. Beta-lactamase enzyme
    - Hydrolyzes beta-lactam ring
  2. Permeability of cell wall
    - Gram neg are impermeable to beta-lactams
  3. Reduced sensitivity of penicillin binding protein
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3
Q

What are penicillin binding proteins

A

Proteins that link to transpeptidase enzyme

Beta lactams bind to PDPs, interfering with transpeptidase reaction

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4
Q

When are beta lactams effective

A

Only during rapid growth stage

because cell-wall synthesis occurs in rapidly growing period

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5
Q

What is natural penicillin derived from

A

Penicillin mold

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6
Q

What spectrum is natural penicillin

A

Narrow

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7
Q

What improves solubility of penicillin G

A

Na/K salts

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8
Q

What improves the half-life of penicillin G

A

Benzathine and Procaine salts

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9
Q

Which natural penicillin is highly inactivated by acidic mediums and thus should only be taken parenteral route

A

Penicillin G

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10
Q

Which natural penicillin is highly stable in a gastric acid medium

A

Penicillin V

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11
Q

Which natural penicillin can be taken orally

A

Penicillin V (acid resistant)

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12
Q

T/F - natural penicillins are good for anerobic infections

A

TRUE

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13
Q

T/F - natural penicillins are good for gram positive aerobic infection

A

True

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14
Q

T/F - natural penicillins are effective against gram negative aerobic and anaerobic infections

A

False! They are only effective against gram + aerobic infections

They are effective against both gram pos/neg anerobes

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15
Q

3 dosage forms of natural penicillin

A
  1. Sodium/potassium salt (Crystalline penicillin)
  2. Procaine penicillin
  3. Benzathine penicillin
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16
Q

Which form of natural penicillin is long acting

A

Procaine penicillin

17
Q

Which form of natural penicillin is good for repositories (IM/intramammary)

A

Benzathine penicillin

18
Q

Which penicillins are resistant against pencillinase

A

Isoxazolyl penicillin (semi-synthetic)

19
Q

Isoxazolyl penicillins (5)

A
  1. Cloxacillin
  2. Oxacillin
  3. Dicloxacillin
  4. Nafcillin
  5. Methicillin
20
Q

Which isoxazolyl penicillins have good oral absorption (acid stable)

A
  1. Cloxacillin
  2. Oxacillin
  3. Dicloxacillin
21
Q

Which isoxazolyl penicillins have poor oral absoprtion

A
  1. Nafcillin

2. Methicillin

22
Q

Microbial susceptibility of penicillinase resistant penicillins

A
  1. Penicillinase producing staph

2. Bacterial infetions of the eye (Staph, Bacillus)

23
Q

Which are broad spectrum penicillins

A

Amoxicillin

Ampicillin

24
Q

Prodrug forms of aminopenicillins (4)

A
  1. Bacampicillin
  2. Hetacillin
  3. Pivampicillin
  4. Talampicillin
25
Q

What are aminopenicillins? Are they sensitive to beta-lactamase?

A

Broadspectrum penicillins

Beta-lactamase sensitive

26
Q

Microbial susceptibility of broad spectrum penicillin

A

All microbes susceptible to natural penicillin

Enterobactericae (gram negs like E. coli, Proteus, Salmonella)

27
Q

What should broad spectrum penicillins be given with

A

Beta-lactamase inhibitors

28
Q

What are Extended Spectrum penicillins effective against

A

Gram neg aerobes/anerobes

Enterobacteriacea

Bacteriodes

PSEUDOMONAS!

29
Q

Extended spectrum penicillins (5)

A

CAMP-T

  1. Carbenicillin
  2. Azocillin
  3. Mezlocillin
  4. Pipercillin
  5. Ticarcillin
30
Q

What should extended penicillins be given with

A

Beta-lactamase inhibitors

31
Q

Which aminopenicillin has greater bioavailability

A

Amoxicillin

Because it is more acid stable —> complete absorption

32
Q

How should procaine penicillin G NEVER be administered

A

IV route – affects cardiac conduction system

33
Q

How should Benzathine penicillin G be administered? Why?

A

IM because its a repository

34
Q

What prolongs penicillin absoprtion by 18h?

A

Suspension in oil

35
Q

Where are penicillins mainly distributed to

A

ECF

36
Q

T/F - penicillins have wide distribution, including to CSF, aqueous humor and synovial fluid

A

False - does not penetrate these structures

37
Q

Which group of penicillins permeates more through cell membrane?

A

Semi-synthetics

38
Q

T/F - lots of penicillin is excreted in milk?

A

True - because the milk:plasma equilibrium concentration ratio is 1:5, meaning it is distributed in milk in lactating animals