Exam 2: Sulfonamides

Question 1

What are the 3 kinds of sulfonamides and how are they administered?

Answer 1

1) sulfamethoxazole: Oral, slow excretion, high urine concentration
2) Sulfasalazine: Oral, used for UC
3) Silver Sulfadiazine- topical, used for burns

Question 2

What is the DOC for UTIs?

Answer 2

Co-trimoxazole

Question 3

What is the MOA of sulfonamides?

Answer 3

Antimetabolites that compete with para-aminobenzoic acid for incorporation into folic acid.
-Bacteriostatic

Question 4

What is the MOA of trimethoprim?

Answer 4

Prevents the reduction of dihydrofolate to tetrahydrofolate which is essential for one carbon transfer

Question 5

Why are sulfamethoxazole and trimethoprim taken together?

Answer 5

They each target different steps and have a synergistic relationship together

Question 6

What are the routes of resistance for sulfamethoxazole and trimethoprim?

Answer 6

• Increased production of an essential metabolite or drug antagonist
• Active Efflux or decreased permeability
• Alternative metabolic pathway for synthesis of essential metabolite

Question 7

Is TMO-SMZ bacteriostatic or cidal?

Answer 7

Cidal in the urine, static everywhere else

Question 8

What is the spectrum of sulfa drugs?

Answer 8

Both G+ and G- organisms (some aerobes and anaerobes)

Question 9

What are the therapeutic uses of sulfasalazine?

Answer 9

A prodrug used in the treatment of mild to moderate UC, Crohns, and RA.

Question 10

When taking Suflamethoxazole trimethoprim, how much higher will the urine concentration be when compared to the plasma concentration?

Answer 10

10-20 times higher

Question 11

What are the toxicities associated with Sulfa drugs?

Answer 11

Blood dyscrasia (asplastic anemia, G6PD deficiency), photosensitivity, hypersensitivity, SJS, kidney/liver damage, and peripheral nerve damage

Question 12

Why shouldn’t sulfas be given to infants?

Answer 12

It can cause Kernicterus because the sulfas compete with the binding of bilirubin to the plasma proteins

Question 13

What drugs so sulfas have cross reactivity with?

Answer 13

Diuretics, celecoxib, and some oral anti diabetic agents

Question 14

What is the MOA of daptomycin?

Answer 14

Binds to Bacterial membranes and causes a rapid depolarization of membrane potential, which leads to inhibition of protein, DNA, and RNA synthesis.

Question 15

How does daptomycin cause membrane depolarization?

Answer 15

It forms transmembrane channels, which allows leakage of intracellular ions and depolarization

Question 16

What the spectrum of Daptomycin?

Answer 16

bactericidal against G+ bacteria (MRSA and MSSA)

• Aerobic or anaerobic
• Concentrastion dependent

Question 17

How does Daptomycin resistance develop?

Answer 17

Resistance is very rare, but does exist. Mechanism for this resistance has not been identified.

Question 18

How is Daptomycin administered?

Answer 18

IV, once daily.

Question 19

What kind of patients is Daptomycin suitable for?

Answer 19

Empiric therapy in patients with serious G+ infections as an alternate to Vancomycin

Question 20

What is the MOA of Mupirocin?

Answer 20

Bacterial protein and RNA synthesis inhibited when mupirocin reversibly binds to bacterial isoleucyl-tRNA synthetase

Question 21

What is the spectrum of Mupirocin?

Answer 21

Good against G+ and G-. Bacteriostatic at low concentrations and cidal at high concentrations.
-Administered topically

Question 22

What is Mupirocin used to treat?

Answer 22

Impetigo caused by S. Aureus.

Intranasal application for pts who carry MRSA

Question 23

What are the two polypeptide antibiotics?

Answer 23

Polymyxin B and Colistin

Question 24

What is the spectrum for polypeptide antibiotics?

Answer 24

G- infections

Question 25

What is the MOA of polymyxin B?

Answer 25

Binds to G- bacterial cell membrane phospholipids. This increases permeability of the cell membrane which results in loss of metabolites essential to bacterial life.

Question 26

Is polymyxin B static or cidal to G- bacilli?

Answer 26

Bactericidal, except for Proteus and Neisseria species

Question 27

What toxicities are associated with the polypeptide antibiotics?

Answer 27

Nephrotoxicity (use topically), paresthesias, ataxia, dizziness, speech disturbances, etc.