Aminoglycosides Flashcards
Are aminoglycosides highly ionized?
Yes. Because they are highly ionized they are extracellular. These do NOT cross the BBB, even with inflammation.
What substance inactivates aminoglycosides in vitro (in a tube or syringe)?
Beta-lactams, so do NOT mix them in the same syringe.
How do aminoglycosides work?
Inhibits protein synthesis at the 30S ribosomal subunit.
Are aminoglycosides bactericidal or bacteriostatic?
Bactericidal.
What are some mechanisms of resistance to aminoglycosides?
Aminoglycoside degradation enzymes in bacteria. Some bacteria even modify their ribosomes to prevent antimicrobial action.
Resistance is primarily plasma-controlled.
Are aminoglycosides time-dependent or concentration-dependent?
Concentration-dependent.
How are aminoglycosides eliminated?
Renal
How are aminoglycosides absorbed?
Little oral absorption.
Well absorbed through all parenteral routes.
What substance is synergistic with aminoglycosides?
Beta-lactams are synergistic with aminoglycosides, even though they inactivate aminoglycosides in vitro.
What do all aminoglycosides work on?
E. coli, Pasteurella, and Staph. Pseudomonas and Lepto.
Gentamicin/Amikacin
NO strep or anaerobic action. Clears the carrier state for Lepto.
Gentamicin: Susceptibility % of gram - in low 90s.
Amikacin: Susceptibility % of gram - in high 90s. Preferred, unless cost is concern. Less nephrotoxic than gentamicin.
Paromomycin
Possible efficacy against cryptosproidiosis.
NEPHROTOXICITY IN CATS!
What are some non-antimicrobial uses for aminoglycosides?
A treatment for glaucoma. After sight has been lost, and if the owner refuses surgical enucleation, gentamicin can be injected into the eye to destroy the ciliary bodies. So, it stops pain by stopping the production of aqueous humor produced by the ciliary bodies.
What are some adverse reactions of aminoglycosides?
Nephrotoxicity (avoid by keeping animal hydrated and monitoring).
Ototoxicity (Deafness, vestibular nerve injury)
Neuromuscular blockage.
Do aminoglycosides work in purulent debris?
Reduced effectiveness.
