Antimicrobial Review (need to know) Flashcards
what ADRs are seen with chloramphenicol
aplastic anemia in people, dose-dependent reversible anemia/neutropenia in cats with >60mg/kg/day, rare aplastic anemia/neutropenia in dogs
what is the most severe ADR associated with clindamycin
fatal diarrhea in horses and rabbits! do not use in them
what drug class is clindamycin in?
lincosamides
what is the most severe ADR associated with erythromycin
fatal diarrhea in adult horses at antibiotic dose
what are the 3rd generation cephalosporins
ceftiofur, cefpodoxime proxetil, cefovecin
what are the 1st generation cephalosporins
cefazolin, cephalexin
which drugs are hydrophilic and thus unable to penetrate abscesses, get into cells, or get into protected sites
aminoglycosides, beta-lactams (penicillins and cephalosporins)
are beta-lactams time or concentration dependent? what does this mean for dosing?
time
need concentrations above MIC for 50% of dosing interval in immunocompetent patients with gram positive infections
80% for gram neg
90% for immunosuppressed
are aminoglycosides time or concentration dependent? what does this mean for dosing?
concentration
Cmax must reach 8-10 times the MIC of the bacteria
increase the dose to get increased concentrations when treating intermediate susceptibility
are fluoroquinolones time or concentration dependent? what does this mean for dosing?
concentration
AUC must reach 100-125 times the MIC of the bacteria for gram negs.
can increase dose and/or decrease interval b/c dose based on area under the curve (do not split dose!)
what is the most important ADR with aminoglycosides and how can this be minimized
nephrotoxicity is associated with a trough concentration >2mcg/mL.
dose SID because a lower dose BID would allow more drug into the cells and increase risk for nephrotoxicity
what dose of enrofloxacin is likely to cause ocular toxicity in cats
5mg/kg or higher
which abx are cell wall synthesis inhibitors? are they static or cidal
beta-lactams
cidal
are protein synthesis inhibitors static or cidal
most are static
aminoglycosides are cidal
what is the MOA of fluoroquinolones
DNA gyrase inhibitors
what is the MOA of nitroimidazoles
DNA synthesis inhibitors thru toxic metabolites
what is the MOA of potentiated sulfonamides
folic acid inhibitors
what is the MOA of beta lactams
cell wall inhibitors
what is the MOA of aminoglycosides
protein synthesis inhibitors - 30s
what is the MOA of tetracyclines
protein synthesis inhibitors - 30s
what is the MOA of macrolides
protein synthesis inhibitors - 50s
what is the MOA of lincosamides
protein synthesis inhibitors - 50s
what is the MOA of phenicols
protein synthesis inhibitors - 50s
what ADRs are seen with potentiated sulfonamides that limit their use
dobermans very predisposed to hypersensitivity reaction (hepatotox, thrombocytopenia). do not use in this breed
should also be avoided in hypothyroid animals
what do you need to keep in mind with ear drops?
gentamycin is ototoxic and should not be used topically with ruptured ear drum
risk of deafness and vestibular dz
what is the spectrum of activity of tetracyclines
jack of all trades. master of rickettsia. lots of resistence out there
what is the spectrum of activity of potentiated sulfonamides
jack of all trades. master of none.
does not cover anaerobes
what is the spectrum of activity of aminopenicillins? which drugs are in this group
strep!!, anaerobes!!, some gram neg aerobes (not a go to for gram negs unless in urine)
amoxicillin and ampicillin
what is the spectrum of activity of aminopenicillins with beta-lactamase inhibitors
same as aminopens alone (strep, anaerobes, some gram neg aerobes) PLUS a good choice for methicillin susceptible staphs and bacteroides
what is the spectrum of activity of 1st gen cephalosporins? which drugs are in this group
strep!!, some meth susceptible staphs, ok for anaerobes, cefazolin ok for gram negs
cefazolin and cephalexin
what is the spectrum of activity of 3rd gen cephalosporins? which drugs are in this group
strep!!, some meth susceptible staphs, some anaerobes, gram negatives at higher doses
ceftiofur best for gram negs
ceftiofur, cefpodoxime proxetil, cefovecin
what is the spectrum of activity of aminoglycosides
gram negatives!!, staphs (reserved for meth resistant ones)
NO strep, NO anaerobes
what is the spectrum of activity of fluoroquinolones
gram neg!!, staph (reserved for meth resistant ones), rickettsia, mycoplasma
rarely strep, NO anaerobes
active in purulent environments
what is the spectrum of activity of macrolides and lincosamides? which drugs are in this group
gram positive aerobes
some anaerobes
-R. equi
good for abscesses and intracellular
macrolides - erthromycin, clarithromycin, azithromycin
lincosamides - clindamycin
what is the spectrum of activity of phenicols? which drugs are in this group
gram positive aerobes, anaerobes, some gram negs, mycoplasma, rickettsia
good for abscesses and intracellular bacteria
what is the spectrum of activity of nitroimidazoles
anaerobes!!! and protozoa
how are beta lactams eliminated
in the urine at high concentrations, so great for UTI!!
what is the general rule for remembering static vs cidal
protein synthesis inhibitors (except aminoglycosides) are static. everything else is cidal
what is the general rule for remembering excretion
macrolides, lincosamides, nitroimidazoles and pradofloxacin mostly hepatic elimination
what is the general rule for remembering distribution
beta-lactams and aminoglycosides are not widely distributed b/c they are water soluble
what is the general rule for remembering oral absorption
benzylpenicillins and aminoglycosides are not orally absorbed in any species
