AMDs and Antifungals Flashcards

1
Q

what is the MoA of Penicillins

A

inhibits cell wall synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the main adverse effects of penicillins (3)

A

1) decrease seizure threshold
2) can cause fatal colitis in hindgut fermenters if given orally
3) hypersensitivities (not given topically)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the main PK features of penicillins (3)

A

1) penicillin G is not acid stable
2) amoxicillin has an oral bioavailability of 90%
3) excreted intact in the urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how should we be treating penicillins

A

1) Penicillin G and amoxicillin
2) Potentiated penicillins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the general spectrum of Penicillin G

A

G+ aerobes, anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the general spectrum of amoxicillin

A

G+ aerobes, anaerobes, some G- aerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

all penicillins end in

A

“cillin”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

do penicillins have a long or short half life

A

short (<2h)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the Vd (high or low) of penicillins and why

A

low; they distribute to extracellular fluids well (not brain or prostate) but have poor penetration of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

if an animal is hypersensitive to penicillins they are also likely reactive to

A

cephalosporins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the MoA of cephalosporins

A

inhibit cell wall synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the major adverse effects of cephalosporins

A

hypersensitivity; colitis in hindgut fermenters if given orally; reduce seizure threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how should we use cephalosporins

A

first line: 1st gen
second line: 3rd gen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the major PK features of cephalosporins

A
  • most are not acid-stable
  • some 3rd gen (cefotaxime) enter CNS readily
  • not destroyed by penicillinases (may be destroyed by β-lactamases)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the general spectrum of first generation cephalosporins

A

same as amoxicillin: G+ aerobes, anaerobes, some G- aerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the issue with cefovecin (Convenia)

A

it is a third generation cephalosporin given as a single SQ injection with a 2-week half-life that essentially guarantees inappropriate duration of therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is a convenient (hint) AMD we should avoid using unless the patient is really aggressive or long duration of therapy needed

A

Cefovecin (Convenia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the main uses of aminoglycosides

A

1) topical infections (ex. staph)
2) serious G- aerobic systemic infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the MoA of aminoglycosides

A

inhibits protein synthesis; bactericidal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the major adverse effects of aminoglycosides

A

nephrotoxicity and ototoxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are the major PK features of aminoglycosides

A

highly ionized so no oral or topical absorption; food residues are over 1y if given parenterally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how should we give aminoglycosides

A

1st line: topical administration
2nd line: systemic administration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the general spectrum of aminoglycosides

A

G- aerobes; mycoplasma; staph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the MoA of tetracyclines

A

inhibit protein synthesis (bacteriostatic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are the major adverse effects of tetracyclines (4)
- nephrotoxicity if dehydrated - esophageal ulcers in cats - tissue irritation - incorporates into growing long bones and teeth
26
what are the major PK features of tetracyclines
lipid soluble useful against intracellular pathogens
27
how do we use tetracyclines
first line, especially important for atypical bacteria (mycoplasma, rickettsia, anaplasma, chlamydia...)
28
what is a highly lipid soluble tetracycline
doxycycline
29
what is the general spectrum of tetracycline in small animals? large animals?
small animals: atypical bacteria large animals: atypical bacteria plus some G+ and G- aerobes and anaerobes
30
if giving tetracyclines what is an important feeding consideration
divalent cations in food (ex. calcium) will markedly decrease oral absorption
31
what tetracycline has the best oral availability
doxycycline
32
why is it a problem that tetracyclines will bind to multivalent cations (ex. calcium)
1) inhibits oral absorption if taken with calcium-containing foods 2) incorporates into growing long bones and teeth which creates food residues
33
what is the MoA of sulphonamides
inhibit folic acid synthesis
34
what are the main adverse effects of sulphonamides (3)
- nephrotoxicity in dehydrated patients - hypersensitivity - lacrimotoxicity in dogs
35
how should we use sulphonamides
first line!
36
what are the main PK features of sulphonamides
inactive in the presence of pus; distributes to all tissues
37
what is the general spectrum of sulphonamides for small animals and for large animals
small animals: UTIs, atypical bacteria large animals: fairly broad spectrum
38
what does TMS stand for and what is it
trimethoprim sulfonamide; it is sulphonamide combined with a diaminopyrimidine inhibitor (trimethoprim) to help restore its effectiveness
39
sulfonamides alone are ____________ whereas trimethoprim sulfonamides are _____________
bacteristatic; bactericidcal
40
what is the MoA of macrolides
inhibit protein synthesis
41
what are the main adverse effects of macrolides
- oral erythromycin causes nausea and vomiting - tissue irritation - potentially fatal colitis if given orally to hindgut fermenters
42
how do we give macrolides
first line: erythromycin second line: newer macrolides
43
what are some key PK features for macrolides
erythromycin: inhibits P450 and stimulates motilin enters cells concentrates in lungs newer macrolides have long half lives
44
in an animal with allergies what is better to give over penicillin
erythromycin
45
macrolides are especially important for ________ disease
respiratory
46
what AMD is fatal to swine and fatal in general if given IV
tilmicosin (a newer macrolide)
47
what is the MoA of fluoroquinolones
inhibit DNA synthesis (DNA gyrases and topioisomerases)
48
what are the main adverse effects of fluoroquinolones
- retinal damage in cats with enrofloxacin - decreased seizure threshold - cartilage damage
49
how do we use fluoroquinolones
second line
50
what are the main PK features of fluoroquinolones
- concentrates in lungs - most have a long half-life (not enrofloxacin) - oral absorption 100%
51
what is the general spectrum of fluoroquinolones
similar to aminoglycosides.... staph, G- aerobes, atypicals
52
what is the general spectrum of macrolides (old vs new)
old (erythromycin): some G- aerobes and some atypical; all G+ aerobes and anaerobes new: all G- aerobes; some G+ aerobes, anaerobes and atypical
53
what drugs should we avoid using if at all possible (3)
fluoroquinolones, potentiated penicillins, 3rd gen cephalosporins
54
what are the 5 main types of antifungals and give an example
- polyenes (amphotericin B) - azoles (itraconazole) - pneumocandins and echinocandins (caspofungin) - pyrimidines - drugs used for dermatophytosis (terbinafine)
55
what is the toxicity and relative spectrum of polyenes? are they fungistatic or fungicidal?
broad spectrum high systemic toxicity fungicidal
56
what is the toxicity and relative spectrum of azoles? are they fungistatic or fungicidal?
very low toxicity broad spectrum fungistatic
57
are pneumocandins/echinocandins high or low toxicity?
low toxicity
58
what is the newest class of antifungal drugs
pneumocandins/echinocandins
59
what is the cell target for: a) pneumocandins b) azoles c) polyenes
a) pneumocandins: cell wall b) azoles: plasma membrane c) polyenes: plasma membrane
60
how do the cell targets of antibacterials differ from antifungals
antibacterials are commonly protein synthesis or cell wall synthesis whereas antifungals are very commonly plasma membrane
61
what allows us to target the plasma membrane of fungi (what is different about the plasma membrane compared to animals cells)
they contain ergosterol instead of cholesterol
62
what are the two "formulations" of amphotericin B (a polyene) and what is the therapeutic difference
1) bile salts: will be eliminated in the kidneys and can cause kidney damage 2) lipid: will be eliminated in the reticuloendothelial system and can be used to target infections there
63
what is the absorption and distribution of amphotericin B
poor oral; given IV; distributes in extracellular fluid but poor CNS penetration
64
what is the half life of amphotericin B
LONG (26h in dogs)
65
what is the spectrum of amphotericin B and what is its main use(s)? how do we usually give it? how does use differ in large animals?
broad (not against dermatophytes); due to toxicity it is usually used topically or for life-threatening systemic mycoses; we usually give one dose of this followed by doses of azoles; not used in food animals and rarely used in equine
66
what is the main adverse effect of amphotericin B
dose-dependent nephrotoxicity (worse with bile salt formulations, better with lipid formulations)
67
how should we go about administering amphotericin B
slow (4-6h) in dextrose-containing IV fluid, may be good to give NaCl fluids before administration to lessen renal toxicity
68
what antifungal can you not give a pregnant dog
azoles (teratogenic)
69
what is the bioavailability of azoles
good oral bioavailability
70
what are the two "types" of azoles and an example? how do we use them?
1) imidazoles (ex. ketoconazole) 2) triazoles (ex. itraconazole) Triazoles better for systemic use but both good for topical use so we use imidazoles first
71
what is the MoA of azoles and an important consideration due to this MoA
inhibits fungal P450 enzymes involved in ergosterol formation it also inhibits some mammalians P450 enzymes making it inhibit the metabolism of other drugs given
72
why do we generally not use imidazoles systemically anymore
endocrine effects common with systemic therapy because they inhibit mammalian sterol synthesis
73
what drug is no longer used as an antifungal but is used to treat hyperadrenocorticism
ketoconazole (an imidazole azole)
74
what are the topical imidazole azoles
miconazole (otic and dermal) clotrimazole (otic) enilconazole (dermal)
75
what is caspofungin and what is it important for
echinocandin; useful against Candida spp.
76
what 2 classes/types of antifungals can be used synergistically against dermatophytes
terbinafine and azoles
77
what are the two ways to administer terbinafine
oral or topical
78
what is the best way to treat severe cases of dermatophytosis
oral and topical combinations of azoles and terbinafine in a clipped animal
79
is therapy long/short for itraconazole and why
long; it enters into newly forming keratin
80
what are the main adverse effects of itraconazole
- GI upset, nausea, vomiting - skin problems - inhibits some P450 enzymes