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SP1 Pharmacology > Lecture 13 3/19/24 > Flashcards

Lecture 13 3/19/24 Flashcards

1
Q

What are the general characteristics of aminoglycosides?

A

-irreversibly bind to 30S ribosomal unit
-bactericidal
-O2-dependent transport
-lose activity in acidic environments
-lose activity due to purulent debris

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2
Q

What is the spectrum of aminoglycosides?

A

-high susceptibility of gram neg. aerobes and FAs
-decent susceptibility of gram pos. FAs
-some susceptibility of gram pos. aerobes
-no susceptibility of anaerobes

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3
Q

Which aminoglycoside has the broadest spectrum of activity?

A

amikacin

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4
Q

Which aminoglycoside is the least nephrotoxic?

A

amikacin

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5
Q

What are the characteristics of aminoglycoside pharmacokinetics?

A

-poor oral absorption
-distribute in extracellular fluid only
-actively accumulated by renal tubular cells
-excreted unchanged in urine via glomerular filtration
-short plasma half-life

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6
Q

What best determines the efficacy of aminoglycosides?

A

how high the peak concentration of the antibiotic is compared to the MIC

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7
Q

Which ratio is best correlated with efficacy for aminoglycosides?

A

Cmax/MIC ratio

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8
Q

What is post-antibiotic effect?

A

residual antibacterial effect seen after concentrations of the antibiotic decrease below the MIC

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9
Q

Which type of drug regimen minimizes adaptive resistance to aminoglycosides?

A

high, infrequent doses

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10
Q

What is adaptive resistance?

A

temporary refractoriness to drug penetration that occurs in bacterial cells surviving the initial ionic binding

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11
Q

What are the characteristics of amingolycoside-related nephrotoxicity?

A

-reversible renal impairment with short term use
-acute tubular necrosis
-more serious renal damage with long term use

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12
Q

Which measurements can indicate nephrotoxicity?

A

-increased GGT:urine Cr ratio
-proteinuria
-elevated BUN and serum creatinine

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13
Q

What allows for aminoglycosides to cause nephrotoxicity?

A

uptake/accumulation of aminoglycosides into the renal tubular epithelium requires a carrier, and thus is saturable

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14
Q

What are the characteristics of aminoglycoside-related ototoxicity?

A

-can be vestibular or cochlear, depending on antibiotic
-usually irreversible
-increased risk when also using diuretics

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15
Q

What are the risk factors for aminoglycoside toxicity?

A

-long duration of therapy
-volume depletion
-pre-existing renal disease
-age
-concomitant nephrotoxic drugs
-elevated trough concentrations

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16
Q

What are the main clinical uses for aminoglycosides?

A

-severe infections with gram neg. aerobes
-local therapy of musculoskeletal infections
-combinations with other drugs

17
Q

Why is extra-label use of aminoglycosides uncommon in food animals?

A

prolonged persistance in renal tissues

18
Q

What is neomycin used for?

A

local treatment of intestinal/wound/ear/skin infections

19
Q

Which strategies can be used when delivering aminoglycosides to a specific region in order to reduce drug exposure?

A

-intravenous regional limb perfusion
-antibiotic-impregnated beads

20
Q

What is intrinsic resistance?

A

when a bacterial species is naturally resistant to a certain antibiotic/family of antibiotics, without need for mutation/gain of further genes

21
Q

What is adaptive resistance?

A

temporary increase in the ability of a bacterium to survive an antibiotic

22
Q

What is acquired resistance?

A

when a particular microorganism obtains the ability to resist the activity of a particular antimicrobial agent to which it was previously susceptible

23
Q

What are the characteristics of PPG + gentamicin?

A

-commonly used in equine practice
-not recommended to mix in same syringe

24
Q

What is the spectrum of PPG + gentamicin?

A

-high susceptibility of gram neg. bacteria and all gram pos. except FAs
-decent susceptibility of gram pos. FAs

25
Q

What are the characteristics of the voluntary aminoglycoside ban in cattle?

A

-not approved for use in cattle
-no established tolerance for aminoglycoside residues in edible cattle tissue
-aminoglycoside use in cattle is legal, but many veterinarians are against it due to kidney residues

26
Q

What are the general characteristics of tetracyclines?

A

-broad spectrum
-increasing acquired resistance
-approved for animal use
-bind to 30S ribosomal subunit
-bacteriostatic

27
Q

What is the spectrum of tetracyclines?

A

decent susceptibility of all bacterial classes

28
Q

Which important species exhibit inherent resistance to tetracyclines?

A

-Pseudomonas
-some Enterobacteriaecae

29
Q

Which important species exhibit acquired resistance to tetracyclines?

A

-Enterococci
-Staphylococci
-Streptococci
-enteric bact.
-gram neg. anaerobes

30
Q

What is important about tetracycline absorption?

A

oral bioavailability is greater for doxycycline and minocycline than older tetracyclines

31
Q

What are the characteristics of tetracycline distribution?

A

-wide distribution, esp. with doxycycline and minocycline
-accumulate in bone and forming enamel
-poor distribution across BBB

32
Q

What are the characteristics of tetracycline elimination?

A

-excreted in urine and bile
-enterohepatic recirculation with half-life of 6-10 hrs

33
Q

What are the characteristics of tetracycline toxicity and adverse effects?

A

-irritants
-disturb intestinal flora
-rapid IV bolus can lead to collapse (fatal in horses)
-pigmentation/softening of teeth in fetus/neonate
-nephrotoxicity

34
Q

What are the primary clinical uses for tetracyclines?

A

-resp. infections
-intracellular organisms

35
Q

Why are tetracyclines not administered via IM in horses and companion animals?

A

-local tissue damage
-local pain
-erratic absorption

36
Q

What are the clinical uses of oxytetracycline and doxycycline in small animals?

A

-UTIs
-brucellosis
-chlamydiosis
-leptospirosis
-Ehrlichia canis
-Rickettsia rickettsi
-Haemobartonella felis

37
Q

What are the clinical uses of doxycycline or minocycline in small animals?

A

-deep tissue infections
-superficial pyoderma
-periodontal disease

SP1 Pharmacology (27 decks)

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