Principles of Antimicrobial Therapy

Question 1

When selecting an antimicrobial, what are the 4 principles you must consider?

Answer 1

1. Confirm presence of infection
2. Identify pathogen
3. Select presumptive therapy
4. Monitor therapeutic response

Question 2

Drug Action and Mechanism is considered to be (pharmacodynamics/pharmacokinetics)

Answer 2

Pharmacodynamics

Question 3

Absorption, Distribution, Metabolism, Excretion is considered to be (pharacodynamics/pharmacokinetics)

Answer 3

Pharmacokinetics

Question 4

What does the body do to the drugs?

Answer 4

Affects serum + tissue levels

Question 5

What reactions occur in phase I metabolism?

Answer 5

Dealkylation, hydroxylation, oxidation, deamination

Question 6

What enzyme system does phase I metabolism occur in?

Answer 6

Cytochrome P-450

Question 7

What does phase I metabolism do exactly?

Answer 7

Inactivates substrate into a more polar compound

Question 8

What reactions occur in phase II metabolism?

Answer 8

Glucuronidation, sulfation, acetylation, conjugation

Question 9

What does phase II metabolism do exactly?

Answer 9

1. Conjugates parent compound with larger molecule to increase polarity
2. Inactivates parent compound, renally excreted

Question 10

What is distribution of a drug affected by?

Answer 10

1. Lipophilicity
2. Partition coefficient
3. Blood flow to tissues
4. pH
5. Protein binding

Question 11

What is bioavailability?

Answer 11

Amount of drug that reaches systemic circulation

Question 12

Glomerular filtration, tubular secretion, passive diffusion + dialysis is considered (renal/non-renal) clearance

Answer 12

renal

Question 13

Sum of clearance pathways not involving the kidneys is considered (renal/non-renal) clearance

Answer 13

non-renal

Question 14

Steady state concentrations reaches after _____ half lives

Answer 14

4 to 5

Question 15

Half-life is affected by changes where?

Answer 15

End-organ function & protein binding

Question 16

How do you find total body clearance?

Answer 16

Renal + Non-renal clearance

Question 17

(Bacteriostatic/Bactericidal) inhibits growth or replication

Answer 17

Bacteriostatic

Question 18

(Bacteriostatic/Bactericidal) causes cell death

Answer 18

Bactercidal

Question 19

Pharmacokinetics

Concentration vs time
Effect vs time
Effect vs concentration

Answer 19

Concentration vs time

Question 20

Pharmacodynamics

Effect vs concentration
Concentration vs time
Effect vs time

Answer 20

Effect vs concentration

Question 21

PK/PD

Effect vs time
Concentration vs time
Effect vs concentration

Answer 21

Effect vs time

Question 22

What is the therapeutic index?

Answer 22

Ratio between toxic and effective dose that shows the normal range of pharmacological effect

Question 23

What is the therapeutic window?

Answer 23

Area between low efficacy and high efficacy of the ED50

Where drug concentrations should be maintained for adequate therapeutic effect

Question 24

What is post antibiotic effect?

Answer 24

Delayed regrowth of bacteria following exposure to antimicrobial

Question 25

If you're allergic to penicillin, what else should you avoid?

Answer 25

Cephalosporin + Carbapenems

Question 26

Can antimicrobials cross the placenta?

Answer 26

Yes

Question 27

Which antibiotics appear to be safe in pregnancy?

Answer 27

1. Penicillins 2. Cephalosporins 3. Erythromycin

Question 28

What are some effects of being pregnant + having antibiotics?

Answer 28

1. Fetus at risk for teratogenicity | 2. Some AB are cleared more rapidly

Question 29

What genetic/metabolic abnormalities should you look out for when taking AB?

Answer 29

G6PD deficiency, risk of increased RBC hemolysis

Question 30

What is the most important factor to consider in antimicrobial selection?

Answer 30

Site of infection

Question 31

Is toxicity a concern for using a combination antimicrobial?

Answer 31

Yes, but can also benefit pt by decreasing toxicity

Question 32

How much evidence is there for using combination antimicrobials?

Answer 32

Theres just weak supporting evidence

Question 33

What kind of effect can you predict from using antimicrobials?

Answer 33

Synergistic, Antagonistic, or no change at all

Question 34

Whats an example of an antagonistic combination therapy?

Answer 34

Using bacteriostatic + bactericidal Tetracycline inhibits growth, but penicillin requires bacteria to grow in order to be effective

Question 35

Whats an example of a synergistic combination therapy?

Answer 35

Using bactericidal and another bactericidal Penicillin + aminoglycoside combination work together great

Question 36

What should you monitor when you use antimicrobials?

Answer 36

Efficacy + toxicity