Nucleic Acid Synthesis and Metabolic Inhibitors

Question 1

What are the 3 AB that inhibit folate synthesis?

Answer 1

Sulfonamides, Trimethoprim, and Dapsone

Question 2

What is Dapsone used for?

Answer 2

PCP prophylaxis in HIV infected person

Alternative to TMP/SMX

Question 3

What is Sulfisoxazole acetyl marketed for and with?

Answer 3

In combo with erythromycin ethylsuccinate for kids w/ otitis media

Question 4

What is the MOA of TMP/SMX?

Answer 4

Inhibits tetrahydrofolate synthesis

Question 5

What is the MOA of trimethoprim?

Answer 5

Inhibits dihydrofolate reductase and in turn reduces it to tetrahydrofolate

Question 6

In general, sulfonamides exert a (bactericidal/bacteriostatic) effect

Answer 6

bacteriostatic

Question 7

What is the spectrum of activity of TMP/SMX?

Answer 7

G+ (strep and staph)
G-
No anaerobes
Pneumocystis jirovecii (PCP)

Question 8

What is the ratio of TMP:SMX in serum/tissue?

Answer 8

1:20

Question 9

What is the ratio of TMP:SMX in a oral/IV dose?

Answer 9

1:5

Question 10

Where is TMP/SMX distributed to?

Answer 10

1. Urine
2. Prostate
3. CSF

Question 11

Why is the use of TMP/SMX generally limited?

Answer 11

Because of resistance

Question 12

What is the drug of choice for treatment and prophylaxis of Pneumocystis jirovecii pneumonia?

Answer 12

TMP/SMX

Question 13

What are the AEs of TMP/SMX?

Answer 13

1. GI issues
2. Hematological (most serious)
3. Skin disorders
4. Sun sensitivity (due to sulfa)

Question 14

What is a serious skin disorder from using sulfa drugs?

Answer 14

Steven’s Johnson Syndrome

Question 15

What are the 1st GEN fluoroquinolones?

Answer 15

Nalidixic Acid

Question 16

What are the 2nd GEN fluroquinolones?

Answer 16

1. Ciprofloxacin
2. Ofloxacin
3. Norfloxacin

Question 17

What are the 3rd GEN fluroquinolones?

Answer 17

Levofloxacin

Question 18

What are the 4th GEN fluroquinolones?

Answer 18

1. Gemifloxacin

2. Moxifloxacin

Question 19

Quinolone antibiotics target what?

Answer 19

Bacterial DNA gyrase and topoisomerase IV

G+; target = Topoisomerase
G-; target = DNA gyrase

Question 20

Which quinolones cover Pseudomonas?

Answer 20

Cipro + Levofloxacin + Delafloxacin

Question 21

Which quinolones cover S. pneum?

Answer 21

Gemifloxacin

Question 22

Which GEN of quinolones has better G+ coverage?

Answer 22

3rd and 4th GEN

Question 23

Which GEN of quinolones has better G- coverage?

Answer 23

They are all about the same

Question 24

What are the atypicals that are covered by quinolones?

Answer 24

1. Legionella pneumophila
2. Chlamydia sp.
3. Mycoplasma sp.

Question 25

Which quinolone has the highest bioavailability?

Answer 25

Levofloxacin (99%)

Question 26

Which quinolone has the least bioavailability?

Answer 26

Norfloxacin (50%)

Question 27

Quinolones are (concentration/time)-dependent

Answer 27

Both

Question 28

What is special about the distribution of quinolones?

Answer 28

Extensive tissue distribution (prostate, liver, lung, skin, bone, urinary tract)

Question 29

What are the AE of quinolones? Which one is the black box warning*?

Answer 29

1. Articular Damage 2. Tendonitis/tendon rupture* 3. Dysglycemias 4. Hypersensitivity 5. Prolongation of QTc interval

Question 30

What medications should you avoid when using quinolones?

Answer 30

Class III (block K+) and Class IA (block K+ and Na+) antiarrhythmics or erythromycin

Question 31

What are some drug interactions with quinolones?

Answer 31

1. Anything w/ divalent or trivalent cations (Calcium, aluminum) 2. Antacids, sucralfate, multivitamins * *administer doses at least 2 hrs apart, take quinolone first

Question 32

What kind of drug is Metronidazole?

Answer 32

Prodrug; only anaerobes convert Flagyl to its active form

Question 33

What is the spectrum of Flagyl?

Answer 33

Anaerobes + Protozoa (Trichomonas vaginalis, amebiasis, and giardiasis)

Question 34

How is Flagyl distributed?

Answer 34

Penetrates CSF

Question 35

What is the half-life of Flagyl?

Answer 35

6 to 8 hrs

Question 36

What is the drug of choice for P. colitis due to C. difficile?

Answer 36

Flagyl

Question 37

What are the AE of Flagyl?

Answer 37

Metallic taste

Question 38

Are there any RX interactions w/ Flagyl?

Answer 38

Alcohol

Question 39

What is Nitrofurantoin used for?

Answer 39

Against G+ or G- infections that cause UTIs