Intro & Sulfonamides - Walters

Question 1

What should you consider when choosing an antibiotic?

Answer 1

1. Resistance
2. Age
3. Hepatic function
4. Genetics
5. Disease state
6. Pregnancy
7. Site of infection
8. Route of administration

Question 2

Sulfonamides

Answer 2

Broad spectrum STATIC antibiotics vs G+ and G- organisms

Question 3

What is the rationale behind multiple Rx therapy?

Answer 3

1. Decreased risk of selecting for resistant organisms
2. Multiple organism infections not covered by a single Rx
3. Synergism - when two drugs produce an effect greater than the sums of either drug alone

Question 4

What is the mechanism of sulfonamides?

Answer 4

Structural analogs of PABA and as such, inhibit dihydroteropate synthase (the first step in synthesis of folic acid)

Question 5

What is commonly used with sulfas for a synergistic effect?

Answer 5

DHFR inhibitor (this reduces FH2 back to FH4; inhibits thymidine synthesis; inhibits organismal DNA synthesis)

Question 6

Trimethoprim

Answer 6

• Bacterial DHFRI

* Side effects: blood dyscrasias

Question 7

Primethamine

Answer 7

• Protozoal DHFRI

* Antimalarial

Question 8

Methrotrexate

Answer 8

• Mammalian, bacterial and protozoal DHFRI

* Used to treat psoriasis and various cancers

Question 9

Pralatrexate

Answer 9

DHFRI used to treat T cell lymphomas

Question 10

Sulfosoxazole

Answer 10

• Oral sulfonamide

* Used w/erythromycin for otitis media

Question 11

Sulfamethoxazole

Answer 11

• Oral sulfonamide
• Used only w/trimethoprim for various urinary, respiratory and GI infections
• Aka Co-trimoxazole; TMP-SMZ

Question 12

Sulfacetamide

Answer 12

• Topical sulfonamide

* Used for ulcerative blepharitis and bacterial conjunctivitis (eye stuff)

Question 13

Silver sulfadiazine

Answer 13

• Topical sulfonamide
• Used for burns and to prevent sepsis
• Silver released is toxic to microorganisms
• CAUTION: potential for extensive systemic absorption

Question 14

Mafenide

Answer 14

• Topical sulfonamide
• Used for burns
• Limited use because can cause metabolic acidosis by inhibiting carbonic anhydrase (leads to loss of HCO3 → loss of buffering capacity)

Question 15

What are some general side effects of all sulfonamides?

Answer 15

1. Crystalluria
2. Kernicterus
3. Blood dyscrasias
4. Hypersensitivity
5. Hyperkalemia

Question 16

Crystalluria

Answer 16

• Crystal formation in nephrons of kidneys

* Incidence low but still recommend drinking lots of water with oral dosage forms to minimize risk of nephrotoxicity

Question 17

Kernicterus

Answer 17

• Bilirubin encephalopathy
• A form of jaundice from displacement of bilirubin from plasma proteins
• Free bilirubin enters CNS & deposits in basal ganglia & other areas → generalized CNS depression

Question 18

Blood dyscrasias

Answer 18

• Acute hemolytic anemia (most serious), agranulocytosis, aplastic anemia
• Rare but can be fatal
• Do not use topicals if there is a known Hx of blood dyscrasias

Question 19

Hyperkalemia

Answer 19

• Too much potassium in blood

* Mainly if there is a co-morbidity

Question 20

Who should NEVER take sulfonamides?

Answer 20

Pregnant ladies during the last months of pregnancy, newborns and infants < 2 years old

Question 21

Erythema multiforme

Answer 21

• Hypersensitivity disorder

* Sudden onset of asymptomatic macules, papules & vesicles on extremities and face

Question 22

Stevens-Johnson syndrome

Answer 22

• Hypersensitivity disorder
• Fever, headache, cough & conjunctivitis followed by macules on face, neck & other areas eventually forming bullous eruptions on skin & mucous membranes

Question 23

Rx fever

Answer 23

• Hypersensitivity disorder

* Immune-mediated hypersensitivity phenomenon

Question 24

Why should kids not be given tetracyclines?

Answer 24

Because it can permanently discolor teeth

Question 25

Which drug is nephrotoxic and ototoxic?

Answer 25

Aminoglycosides

Question 26

Which drugs have a higher risk of causing hemolysis if low levels of G6PD?

Answer 26

1. Sulfonamides 2. Nitrofurantoin 3. Chloramphenicol

Question 27

Which drugs can give you a false + for urine sugar?

Answer 27

1. PCNs 2. Cephalosporins 3. Tetracyclines

Question 28

Which antibiotics can be given orally for a local effect?

Answer 28

1. Aminoglycosides | 2. Vancomycin

Question 29

What does a STATIC antibiotic do?

Answer 29

Inhibits metabolic pathway

Question 30

What does a CIDAL antibiotic do?

Answer 30

Kills organism directly by lysis

Question 31

What is the best way to use multiple antibiotic therapy?

Answer 31

Use two drugs that act by different mechanisms! | The more different steps in an organism's life cycle you can disrupt, the more likely you'll be to kill it

Question 32

What are two examples of synergism?

Answer 32

1. Sulfonamide + trimethoprim = inhibit sequential steps in synthesis of folate 2. PCNs + gentamicin (or streptomycin) = PCN inhibits the uptake of the other 1 and is used in treating enterococcal endocarditis

Question 33

What pregnancy category do sulfonamides fall into?

Answer 33

B (is for bitches)

Question 34

What drug can sulfas displace?

Answer 34

Warfarin from albumin