Antibacterials II Flashcards
What are the classifications of antimicrobials?
Inhibitors of cell synthesis
Inhibitors of protein synthesis
Inhibitors of folic acid synthesis
Inhibitors of DNA synthesis and structure
What are the examples of inhibitors of protein synthesis?
Aminoglycosides, Chloramphenicol, Tetracyclines, Macrolides, and Lincosamides
What are aminoglycosides?
Two amino sugars joined by a glycoside linkage to a central hexose nucleus
Where are aminoglycosides derived from?
Streptomycins (have a -mycin ending)
Micromonospora (have a -micin ending)
What is the spectrum for aminoglycosides?
Broad gram negative
What is the pharmacokinetics of aminoglycosides?
Mostly given intravenously
Mostly excreted unchanged in the urine
What is the exception of aminoglycosides regarding pharmacokinetics?
Neomycin - because of nephrotoxicity
It is used topically
Why should plasma drug levels be monitored while on aminoglycosides?
They have a low therapeutic index so monitoring is important in order to prevent a toxic effect
What characteristics do aminoglycosides exert?
Concentration-dependent bactericidal activity and post-antibiotic effect.
What is the mechanism of aminoglycosides?
Inhibit bacterial protein synthesis
How do aminoglycosides inhibit bacterial protein synthesis?
Diffuse through porin channels in the outer membrane; use the oxygen-dependent system to move across the cytoplasmic membrane
Where do aminoglycosides bind in the ribosome?
They bind to the 30s subunit
What effect does the binding of aminoglycosides to the 30s subunits have?
Distorts the structure and causes misreading of the mRNA
What is the therapeutic use of aminoglycosides?
Effective for the majority of aerobic gram (-) bacilli
Often combined with a β-lactam for synergistic effect
Treatment of serious infections due to aerobic gram (-) bacilli, serious toxicity limits their clinical utility.
What multidrug-resistant pathogens are sensitive aminoglycosides?
Pseudomonas aeruginosa,
Klebsiella pneumoniae,
Enterobacter sp.
What is the resistance of aminoglycosides?
Efflux pumps, decreased uptake, and/or modification and inactivation by plasmid-associated synthesis of enzymes
What are the adverse effects of aminoglycosides?
Ototoxicity
Nephrotoxicity
Neuromuscular paralysis & allergic reaction