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35 Cards in this Set
- Front
- Back
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Aminoglycside
-drugs |
-Neomycin
-Amikacin -Gentamicin |
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Which aminoglycoside is not very effective anymore?
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-neomycin
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Aminoglycoside
-physiochemical properties |
-highly hydrophilic, lipid insoluble
-minimally absorbed from the gut (3-5%) -minimally bound to plasma protein, but readily bind to cellular debris |
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Why do aminoglycosides have a low volume of distribution?
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-highly hydrophyilic, and lipid insoluble
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Only reason to give aminoglycosides orally
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-enteric infection
-minimal absorption in the gut (3-5%) |
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Aminoglycoside
-mechanism of action |
-protein synthesis inhibition
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Why is the mechanism of drug action for Aminoglycosides a unique situation?
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-They are a protein synthesis inhibitor that is bactericidal
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Why don't aminoglycosides work well against intracellular bacteria?
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-hydrophilic nature gives poor penetration into bacteria
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Aminoglycoside penetration into bacteria
-dependent on |
-Energy dependent phase I
-Energy dependent phase II |
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Aminoglycoside
-Energy dependent phase I |
-oxygen dependent
-blocked by hyperosmolarity, low pH, anaerobic condition |
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Aminoglycoside
-Energy dependent phase II |
-involves disruption of the cytoplasmic membrane
-explains bactericidal action |
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Aminoglycoside
-Spectrum |
-Aerobic Gram (-) bacteria (bacilli)*
-Some Gram (+) cocci |
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Aminoglycoside with the broadest spectrum
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-Amikacin
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Why does Amikacin have the broadest spectrum of aminoglycosides?
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-more resistant to enzymes produced by enterobacteriaceae so it may be effective when there is resistance with gentamicin and tobramycin
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Aminoglycoside
-routes of administration |
Systemic: (INJECT!)
-IV -IM -SC Gastrointestinal: -oral |
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Aminoglycoside
-effects of being lipid insoluble |
-limited capacity to penetrate cellular membranes
-minimal absorption after oral administration -low volume of distribution -minimal distribution in CNS -volume of distribution higher in neonates (higher amount of ECF) |
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Aminoglycosides
-locations of highest tissue concentration |
-renal cortex
-cochlear tissue |
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Why do the renal cortex and cochlear tissue have the highest concentration of aminoglycosides?
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-highest concentration of phospholipids in their cellular matrix
-anionic nature of phospholipids attract cationic aminoglycosides |
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Aminoglycosides
-primary route of excretion |
-kidneys
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Aminoglycosides
-urine concentration vs. serum conc. |
urine concentration can be 100x serum
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How should Aminoglycosides never be administered?
-why? |
never administer via CRI
-aminoglycoside are peak dependent bactericidal compounds |
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Aminoglycosides
-peak serum concentration |
-8-10x MIC of the target pathogen
-once per day |
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Aminoglycosides
-adverse reactions |
-renal toxicity
-ototoxicity -neuromuscular blockade -excessive withdrawals for extra-label use in food animals |
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Aminoglycoside that can cause the most severe renal toxicity
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-neomycin (don't use systemically)
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Aminoglycosides
-what can increase the nephrotoxic potential |
concurrent use with:
-loop diuretics -osmotic diuretics |
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Aminoglycosides
-how is nephrotoxicity best avoided |
-allow the serum concentration to fall below the critical trough concentration prior to the following dose
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Aminoglycosides
-phases of nephrotoxicity |
-initial nonazotemic phase
-clinical azotemic phase (once in this phase, stopping aminoglycoside therapy will most likely not stop azotemia) |
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Aminoglycosides
-species susceptible to vestibular effects |
-cats
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Aminoglycosides
-species susceptible to auditory symptoms |
-dogs (might be a problem with working dogs)
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Aminoglycosides
-neuromuscular blockade may occur when |
use is concurrent with:
-general anesthetics -neuromuscular blocking agents |
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Aminoglycosides
-only food animal injectable labeled for gentamicin |
-IM injection in pigs up to 3 days old for treatment of coliobacillosis
-all other labels are oral |
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Aminoglycosides
-only beef cattle label for gentamicin |
-pinkeye spray
(no serum concentration detectable after use, so no tolerance for gentamicin in bovine tissue) |
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Aminoglycosides
-neomycin label in beef cattle |
-oral use only
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Aminoglycoside
-slaughter withdrawal time of gentamicin in cattle |
-18 months (FARAD)
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Aminoglycosides
-therapeutic index |
-very narrow (even when hydrated)
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