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Pharmacology > AB - Sulfonamides and penicillins > Flashcards

AB - Sulfonamides and penicillins Flashcards

1
Q

What class of antibiotics are sulfonamides?

A

Folic acid synthesis inhibitors

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2
Q

What are the most common sulfonamides used in veterinary medicine?

A

Sulfadiazine, Sulfadoxine, Sulfanilamide, Sulfamerazine, Sulfamethazine

Don’t need to know this list though - assume anything that has sulfa- is a sulfonamide

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3
Q

Are sulfonamides bacteriostatic or bactericidal?

A

Bacteriostatic

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4
Q

Sulfonamides are _______ dependent

A

Time

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5
Q

What bacteria do sulfonamides have activity against?

A

Aerobic Gram-positive and Gram-negatives

Also have activity against protozoa and coccidia (ex. toxoplasma, sarcocystis, eimeria)

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6
Q

Sulfonamides are not effective against which condition(s)?

A

Tissue infections with abscessation, as high levels of PABA and thymidine in abscessed tissues can inhibit their activity

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7
Q

True or False: Sulfonamides are excreted unchanged through the kidney

A

True (so they can be used for urinary tract infections)

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8
Q

What are potentiated sulfonamides?

A

Sulfonamides used in combination with diaminopyrimidines (better antimicrobial activity)

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9
Q

Why do potentiated sulfonamides lead to better activity?

A

They are both folic acid synthesis inhibitors, but together they have synergistic action (inhibit folic acid synthesis at two sites in the pathway)

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10
Q

What is the difference between diaminopyrimidines and sulfonamides?

A

Diaminopyrimidines penetrate the cell membranes via diffusion, unlike sulfonamides which stay in the extracellular fluid

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11
Q

Are potentiated sulfonamides bacteriostatic or bactericidal?

A

Bactericidal

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12
Q

Potentiated sulfonamides are _______ dependent

A

Time

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13
Q

Potentiated sulfonamides have good penetration into which two anatomical areas?

A

The CNS and prostate

(ex. prostatitis)

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14
Q

What is the most common diaminopyrimidine used in veterinary medicine?

A

Trimethoprim

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15
Q

What is the most common potentiated sulfonamide used in veterinary medicine?

A

Trimethoprim/sulfadiazine (TMS)

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16
Q

What are three adverse effects of trimethoprim/sulfadiazine?

A

Keratoconjunctivitis sicca, Hypothyroidism, Crystaluria

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17
Q

What class of drug is trimethoprim/sulfadiazine?

A

Potentiated sulfonamide

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18
Q

Trimethoprim/sulfadiazine is not effective against which condition(s)?

A

Abscesses

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19
Q

True or False: Trimethoprim/sulfadiazine (TMS) can be used in horses

A

True, in fact trimethoprim/sulfadiazine is one of the only safe oral antibiotics in horses

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20
Q

What is trimethoprim/sulfadiazine used for in horses?

A

Respiratory infections, Wounds, Perioperative infections, Hepatitis

Also labelled for acute strangles but remember that it’s not good at penetrating abscesses

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21
Q

What is trimethoprim/sulfadiazine used for in dogs?

A

Respiratory infections, Bite wounds, UTIs, Skin infections

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22
Q

Potentiated sulfonamides are category _________ drugs

23
Q

What class of antibiotics are penicillins?

A

Beta-lactams (cell wall disruptors)

24
Q

What is the mechanism of action of beta-lactam antibiotics?

A

β-lactams in penicillin bind to penicillin binding proteins in bacteria cell walls (PBPs cross-link peptidoglycans) and inactivate them, causing death

25
Why don't beta-lactam drugs have adverse effects in humans?
Because mammalian cells don't have cell walls
26
What component of the bacterial cell makes it more difficult for beta-lactam antimicrobials to reach PBPs? In which type of bacteria is this found?
An outer cell membrane (found in Gram-negatives but not Gram-positives)
27
Are beta-lactams bacteriostatic or bactericidal?
Bactericidal
28
Beta-lactams are _______ dependent
Time
29
True or False: Beta-lactams are excreted unchanged through the kidney
True (so they can be used for urinary tract infections)
30
What anatomical locations do beta-lactams not penetrate well?
CSF, Joints, Eyes, Milk
31
True or False: Beta-lactam antibiotics have a post-antibiotic effect
True, but remember it occurs only against Gram-positive bacteria
32
Which drugs should not be combined with beta-lactam drugs and why?
Bacteriostatic antimicrobials. Beta-lactams work best when acting on growing populations of bacteria, so it's not recommended to give in combination with bacteriostatic antimicrobials (will inhibit their effects)
33
What are three mechanisms of resistance to beta-lactam antibiotics?
1. β-lactamase production (attacks beta-lactam drugs) 2. Reduced penetration through outer cell membrane (due to efflux pumps) 3. Altered targets (PBPs that resist binding by β-lactams)
34
What is penicillin G? How should it be administered?
A type of natural penicillin. It should be administered IV (unless its not the sodium or potassium form) because it is easily destroyed by stomach acid
35
What are the four forms of Penicillin G?
Potassium penicillin G, Sodium penicillin G, Procaine penicillin G, Benzathine penicillin G
36
True or False: Penicillin G is commonly given orally
False, it is almost never given orally
37
Which forms of Penicillin G are not safe to give IV and why?
Procaine and benzathine as CNS toxicity (procaine) or cardiac arrest (benzathine) may result! Potassium and sodium is safe to give IV.
38
Penicillin G is __________ spectrum
Narrow
39
What is Penicillin G especially susceptible to?
Degradation by β-lactamase
40
Which specific bacteria is Penicillin G effective against?
Anaerobes (ex. Fusobacterium, Clostridium), Spirochetes (ex. Leptospira, Borrelia), Streptococcus (NOT Staphylococcus)
41
What must you be cautious about when administering penicillin G?
Penicillin G is not usually given orally (usually given IM), and that inadvertant IV administration must be avoided when using procaine penicillin G or benzathine penicillin G, as CNS toxicity (procaine) or cardiac arrest (benzathine) may result.
42
What are the two common aminopenicillins given in veterinary medicine?
Amoxicillin and ampicillin
43
How are amoxicillin and ampicillin different from penicillin G?
They are active against the same bacteria as penicillin G, except better at penetrating Gram-negative cell membranes (broader spectrum)
44
Which drug should never be given orally to hindgut fermenters?
Penicillins (causes critical dysbiosis)
45
Which penicillins are resistant to penicillinase?
Cloxacillin and methicillin
46
What is cloxacilin's main activity against?
Staphylococcus spp. (but also has activity against some Gram-positives, Gram-negatives, and spirochetes)
47
Cloxacillin is rarely used clinically except for what?
Mastitis (intramammary administration) ## Footnote Remember that beta-lactams like penicillins do not distribute well into milk when given systemically
48
What does it mean if a culture and sensitivity test shows a resistance to penicillinase-resistant penicillin?
Do not use any beta-lactam drugs! This is a methicillin resistant Staphylococcus (MRSA or MRSP)!!
49
What are potentiated penicillins?
A drug that combines a β-lactamase inhibitor and a penicillin
50
Name one potentiated penicillin
Clavulanic acid/amoxicillin (Clavamox)
51
Clavulanic acid/amoxicillin (Clavamox) can be absorbed in all tissues except which one?
The CNS
52
Clavulanic acid/amoxicillin (Clavamox) is a category ________ drug
2
53
What is the only β-lactamase inhibitor that is absorbed orally?
Clavulanic acid/amoxicillin (Clavamox)

Pharmacology (23 decks)

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