aminoglycosides Flashcards
(42 cards)
Some drugs and aminoglycosides
• As the plasma level is increased above the MIC, the drug kills an increasing proportion of bacteria at a more rapid rate
conc dependent
Any antibiotic, including penicillins and cephalosporins
• Directly related to time above MIC
• Independent of concentration once the MIC is reached
TIME DEPENDENT
Structurally related amino sugars attached by glycosidic linkages
aminoglycosides
are aminoglycosides polar or not
polar
RoA of aminoglycosides
Given intramuscularly or intravenously for systemic effects
Are aminoglycosides absorbed orally?
no
tissue penetration of aminoglycosides (full partial limited)
Limited
Does it readily cross the blood-brain barrier
no
Major mode of excretion
•
Glomerular filtration
Excretion is directly proportional to —- clearance
creatinine
With normal renal function, elimination half-life is
2-3 h
Peak serum levels
Measured at
30-60 minutes after administration
Trough serum levels
Measured when
just before the next dose
MoA of AG
Bactericidal (irreversible) inhibitors of protein synthesis
Penetration of bacterial cell wall is partly dependent on ___________
O2-dependent active transport
Transport is enhanced by ________
cell wall synthesis inhibitors
Bind to _____ AND Interfere with protein synthesis
30S ribosomal unit
ag interfere with protein synthesis by
- Block formation of initiation complex
- Cause misreading of the code on the mRNA template
- Inhibit translocation
MECHANISMS OF RESISTANCE
Failure to penetrate into the cell
Plasmid-mediated formation of inactivating enzymes
• Primary mechanism of resistance
Plasmid-mediated formation of inactivating enzymes
•
Catalyze the acetylation of amine functions
Transfer of phosphoryl or adenyl groups to the O2 atoms of hydroxyl groups on the aminoglycoside
Group transferases
transferases produced by enzyme can inactivate
- Amikacin
- Gentamicin
- Tobramycin
- Not streptomycin
- Netilmicin is less susceptible and is active against more strains of organisms
for Serious infections caused by aerobic gram (-) bacteria • E. coli Enterobacter • Klebsiella Proteus • Providencia Pseudomonas • Serratia
GENTAMICIN, TOBRAMYCIN, and AMIKACIN
Tuberculosis
Plague
Tularemia
Multi-drug-resistant (MDR) strains of M. tb resistant to streptomycin maybe susceptible to amikacin
STREPTOMYCIN