Beta Lactams

Question 1

What is the target of beta-lactams?

Answer 1

Transpeptidase enzyme

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

Question 2

Microbial resistance to beta-lactams

Answer 2

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

Question 3

What are penicillin binding proteins

Answer 3

Proteins that link to transpeptidase enzyme

Beta lactams bind to PDPs, interfering with transpeptidase reaction

Question 4

When are beta lactams effective

Answer 4

Only during rapid growth stage

because cell-wall synthesis occurs in rapidly growing period

Question 5

What is natural penicillin derived from

Answer 5

Penicillin mold

Question 6

What spectrum is natural penicillin

Answer 6

Narrow

Question 7

What improves solubility of penicillin G

Answer 7

Na/K salts

Question 8

What improves the half-life of penicillin G

Answer 8

Benzathine and Procaine salts

Question 9

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

Answer 9

Penicillin G

Question 10

Which natural penicillin is highly stable in a gastric acid medium

Answer 10

Penicillin V

Question 11

Which natural penicillin can be taken orally

Answer 11

Penicillin V (acid resistant)

Question 12

T/F - natural penicillins are good for anerobic infections

Answer 12

TRUE

Question 13

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

Answer 13

True

Question 14

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

Answer 14

False! They are only effective against gram + aerobic infections

They are effective against both gram pos/neg anerobes

Question 15

3 dosage forms of natural penicillin

Answer 15

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

Question 16

Which form of natural penicillin is long acting

Answer 16

Procaine penicillin

Question 17

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

Answer 17

Benzathine penicillin

Question 18

Which penicillins are resistant against pencillinase

Answer 18

Isoxazolyl penicillin (semi-synthetic)

Question 19

Isoxazolyl penicillins (5)

Answer 19

1. Cloxacillin
2. Oxacillin
3. Dicloxacillin
4. Nafcillin
5. Methicillin

Question 20

Which isoxazolyl penicillins have good oral absorption (acid stable)

Answer 20

1. Cloxacillin
2. Oxacillin
3. Dicloxacillin

Question 21

Which isoxazolyl penicillins have poor oral absoprtion

Answer 21

1. Nafcillin

2. Methicillin

Question 22

Microbial susceptibility of penicillinase resistant penicillins

Answer 22

1. Penicillinase producing staph

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

Question 23

Which are broad spectrum penicillins

Answer 23

Amoxicillin

Ampicillin

Question 24

Prodrug forms of aminopenicillins (4)

Answer 24

1. Bacampicillin
2. Hetacillin
3. Pivampicillin
4. Talampicillin

Question 25

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

Answer 25

Broadspectrum penicillins Beta-lactamase sensitive

Question 26

Microbial susceptibility of broad spectrum penicillin

Answer 26

All microbes susceptible to natural penicillin Enterobactericae (gram negs like E. coli, Proteus, Salmonella)

Question 27

What should broad spectrum penicillins be given with

Answer 27

Beta-lactamase inhibitors

Question 28

What are Extended Spectrum penicillins effective against

Answer 28

Gram neg aerobes/anerobes Enterobacteriacea Bacteriodes PSEUDOMONAS!

Question 29

Extended spectrum penicillins (5)

Answer 29

CAMP-T 1. Carbenicillin 2. Azocillin 3. Mezlocillin 4. Pipercillin 5. Ticarcillin

Question 30

What should extended penicillins be given with

Answer 30

Beta-lactamase inhibitors

Question 31

Which aminopenicillin has greater bioavailability

Answer 31

Amoxicillin Because it is more acid stable ---> complete absorption

Question 32

How should procaine penicillin G NEVER be administered

Answer 32

IV route -- affects cardiac conduction system

Question 33

How should Benzathine penicillin G be administered? Why?

Answer 33

IM because its a repository

Question 34

What prolongs penicillin absoprtion by 18h?

Answer 34

Suspension in oil

Question 35

Where are penicillins mainly distributed to

Answer 35

ECF

Question 36

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

Answer 36

False - does not penetrate these structures

Question 37

Which group of penicillins permeates more through cell membrane?

Answer 37

Semi-synthetics

Question 38

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

Answer 38

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