Sulfonamides

Question 1

Sulfonamides are bactericidal/bacteriostatic

Answer 1

bacteriostatic

Question 2

Sulfonamide is a generic term for

Answer 2

derivatives of para-aminobensenesulfonamide

Question 3

sulfonamide compounds used today

Answer 3

Bactrim and sulfadiazine

topical: mefenide, silver sulfadiazine, sulfacetamide

Question 4

The structure prerequisites for activity are embedded in the

Answer 4

sulfanilamide

Question 5

addition of the heterocyclic aromatic ring on sulfamethoxazole helps with

Answer 5

antibacterial activity

Question 6

Bacteria synthesize their own ____ utilizing _____

Answer 6

folic acid; PABA

Question 7

Sulfonamides are structural analogues of

Answer 7

PABA

Question 8

Sulfonamides competitively inhibit

Answer 8

dihydroteroate synthase which is an enzyme responsible for incorporating PABA into the dihydropteroic acid

Question 9

Sulfonamides will only affect organisms that

Answer 9

must synthesize their own folic acid

Question 10

Synergy with trimethoprim:

Answer 10

potent inhibitor of dihydrofolate reductase which reduces tetrahydrofolate concentrations

Question 11

TMP/SMX oral absorption

Answer 11

97%

Question 12

TMP/SMX 1/2 life

Answer 12

8-10/10 hours

Question 13

TMP/SMX elimination

Answer 13

sulfa: 30% free in urine and 70% acetylated in liver
TMP: 100% renal

Question 14

Sulfadiazine oral absorption

Answer 14

100%

Question 15

sulfadiazine 1/2 life

Answer 15

17 hours

Question 16

sulfadiazine elimination

Answer 16

60% free in urine

40% acetylated

Question 17

Dosing for pneumocystis jiroveci

Answer 17

15-20 mg/kg/day divided q8h (IV)

Question 18

Cystitis dosing

Answer 18

1 DS po q12h

Question 19

S. aureus ABSSSI dosing

Answer 19

1-2 DS po q12h

Question 20

Other indications for sulfonamides

Answer 20

prophylaxis, nocardia

Question 21

SMX/TMP SS

Answer 21

400mg/80mg

Question 22

SMX/TMP DS

Answer 22

800mg/160mg

Question 23

intensity of dosing regimen id driven by

Answer 23

organism and site of infections

Question 24

Dosing is based on

Answer 24

trimethoprim component

Question 25

which body weight should be used when obese?

Answer 25

adjusted

Question 26

Renal adjustment is needed/is not needed

Answer 26

needed

Question 27

Sulfonamide spectrum coverage

Answer 27

dark purple: s. pneumoniae, MSSA, MRSA light purple: streptococcus dark red: h, influenzae, m, catarrhalis, E. coli, klebsiella, p. mirabilis, morganella, enterobacter light red: Neisseria Misc: TMP/SMX activity against pneumocystis jiroveci, salmonella, shigella, vibrio, steno, nocardia, listeria

Question 28

Sulfonamide resistance mechanisms

Answer 28

permeability barrier/efflux (pseudomonas) insensitive targets -altered binding to dihydrofolate reductase; point mutations can minimize ability of TMP to bind, natural resistance for bacteriodes and clostridium and acquired resistance for e.coli, s.aureus, s.pneumoniae, h. influenzae -altered binding to dihydropteroate synthase ; acquired resistance: e.coli, s.aureus, campylobacter, and h. pylori

Question 29

Resistance mechanisms can

Answer 29

easily be transferred to other organisms

Question 30

Sulfonamides adverse effects

Answer 30

``` GI hypersensitivity photosensitivity hyperkalemia increased serum creatinine interstitial nephritis or crystalluria pregnancy category D G6PD deficiency folate deficiency anemia can exacerbate anemia ```

Question 31

Sulfonamides are pregnancy category

Answer 31

D; 1st trimester congenital abnormalities | near term: increased risk for jaundice, hemolytic anemia, or kerniceterus (readily crosses placenta)

Question 32

TMP drug interactions

Answer 32

dofetilide, phenytoin, warfarin, digoxin

Question 33

TMP is an inhibitor of

Answer 33

CYP2C8 and OCT2

Question 34

SMX drug interactions

Answer 34

nephrotoxic agents methenamine elvitegravir

Question 35

SMX is an inhibitor and substrate of

Answer 35

CYP2C9

Question 36

TMP/SMX indications

Answer 36

1st line for pneumocystis (treatment and prevention), nocardia, s. maltophilia, B. cepacia good activity for MRSA inferior to beta lactams for MSSA transition agent when susceptibilities are available (enterobacteriaceae)

Question 37

Sulfadiazine indications

Answer 37

treatment of toxoplasmosis

Question 38

Which of the following electrolytes do you monitor while on TMP/SMX? a. megnesium b. calcium c. potassium d. sodium

Answer 38

c

Question 39

Which antibiotic targets dihydrofolate reductase?

Answer 39

trimethoprim

Question 40

Which antibiotic targets dihydropteroate synthase?

Answer 40

sulfonamides

Question 41

TMP/SMX is the drug of choice for which of the following? a. p. aeruginosa b. e. coli c. s. pyogenes d. p. jiroveci

Answer 41

d