Aminoglycosides Flashcards
aminoglycosides are ___________________ at physiologic pH
highly ionized
what is the absorption/route like of aminoglycosides?
minimal oral absorption
well absorbed by all parenteral routes
what is the distribution of aminoglycosides?
mostly extracellular
how are aminoglycosides excreted?
mostly renal filtration and concentrates in urine
how do aminoglycosides have a bacteriocidal effect?
protein synthesis inhibition at 30S ribosomal subunit
only protein synthesis inhibitor that is actually bacteriocidal
what blocks the oxygen dependent, active uptake at the cytoplasmic membrane of aminoglycosides?
hyperosmolarity
low pH
anaerobic conditions
efficacy of aminoglycosides is associated with Cmax plasma concentration _________ the MIC
8-10x
what is neomycin commonly used for?
enteric and topical infections
what is neomycin too toxic for?
to use parenterally
what is Tobramycin used primarily for in veterinary medicine?
ophthalmic infections
what are two aminoglycosides that are used systemically and topically?
gentamicin
amikacin
how effective is gentamicin against E. coli?
very effective
what are the adverse effects of aminoglycosides?
nephrotoxicity
ototoxicity
neuromuscular blockade
what is gentamicin’s spectrum in general?
gram negatives
what is the most common aminoglycoside toxicity in veterinary medicine?
aminoglycoside nephrotoxicity
what is aminoglycoside nephrotoxicity associated with?
prolonged high trough concentrations
what does the covalent binding of aminoglycosides to intracellular organelles in the proximal renal tubules mean for food animals?
extra-label use in cattle is suggested at 18 months
highly discouraged from use in food animals
how can you reduce the likelihood of aminoglycoside nephrotoxicity?
keep the patient well hydrated
limit other nephrotoxic drugs if possible
perform therapeutic drug monitoring
what should you monitor for aminoglycoside nephrotoxicity?
increases in serum BUN or creatinine occur too late to be helpful
perform serial urinalyses: increasing tubular casts, increasing protein, possible increasing specific gravity and glucose
should you use increases in serum BUN or creatinine to monitor aminoglycoside nephrotoxicity?
no- increases in serum occur too late to be helpful
is it okay to use aminoglycosides on the ears with a ruptured tympanic membrane?
no: ototoxicity, deafness
do aminoglycosides ever cross the blood brain barrier?
no- not even with inflammation
are aminoglycosides bactericidal or bacteriostatic?
bactericidal
can tobramycin be used systemically?
yes
what is the four quadrant coverage of gentamycin/aminoglycosides?
E. coli: +++
Staphylococcus: (+)
Streptococcus: -
anaerobe: -
what is the spectrum of gentamycin in general?
gram negative
in whom is therapeutic drug monitoring more important for aminoglycosides?
geriatric and in animals with conventional divided dosing regimens
is aminoglycoside ototoxicity reversible by stopping the drug?
no- often permanent
when prescribing an aimonglycoside, what should you check in the ears for?
intact tympanic membrane
what drugs used for ears contain gentamycin?
otomax
mometamax
can you see ototoxicity with parenteral use of aminoglycosides?
yes
what is an aminoglycoside neuromuscular blockade associated with?
high plasma concentrations of aminoglycosides following rapid IV injection or general anesthesia
is Pseudomonas easy to get rid of?
highly resistant
what is it an indicator of if anitmicrobials are effective against Pseudomonas?
strong gram negative action
what is Pseudomonas associated with?
melting corneal ulcers
otitis externa
wounds
pneumonia
what are some not topical products that are effective against Pseudomonas?
anti-pseudomonal penicillins
carbapenems
ceftazidime
