Aminoglycosides and Tetracyclines Flashcards
(29 cards)
What type of drug is Gentamicin?
Aminoglycoside
What type of drug is tobramycin:
Aminoglycoside
What type of drug is amikacin?
Aminoglycoside
MOA of aminoglycoside
Binds irreversibly to bacterial ribosomes which inhibits protein synthesis
What is the basis for protein synthesis?
Protein synthesis follows transcription, which involves the synthesis of single-stranded RNA transcripts from a DNA template
Once the mRNA transcripts are synthesized, these transcripts are translated by the bacterial translational machinery
What does gentamicin target?
Gram neg bacteria, gram pos staphylococci, gram pos mycoplasma
What is tobramycin used to treat & how?
Used topically to treat bacteria that is resistant to gentamicin
The 70S ribosome of a bacterium is comprised of ____
A 30S subunit and a 50S subunit
Two mechanisms by which bacterial resistance to aminoglycosides can occur:
Constitutive resistance: Anaerobes lack the oxygen-dependent transport processes that are necessary for aminoglycosides to enter the cell
Plasmid-acquired resistance: Production of aminoglycoside modifying enzymes which modify and inactivate the drug
Aminoglycosides work synergistically with drugs that interfere with _____
Cell wall
Bioavailability of aminoglycosides:
Very low oral absorption, must be given parenterally
Adverse effects of aminoglycosides:
Nephrotoxicity, ototoxicity
How can nephrotoxicity be minimized following aminoglycoside treatment?
Allowing a washout period each day
- A single daily dose and allowing concentrations to fall for remainder of day
What is targeted by aminoglycoside-induced ototoxicity?
Damage to cranial nerves (CN VIII) and hair cells in the cochlea and vestibular apparatus
Tetracyclines are mainly used to treat ____
Atypical bacteria (neither gram pos or neg)
Where do tetracyclines bind?
30S subunit on ribosomes
MOA of tetracyclines:
Prevent binding of aminoacyl-tRNA through allosterically binding to the ribosome
This binding is irreversible, leading to bacteriostatic effect
Atypical bacterial infections examples:
Rickettsia, chlamydia, mycoplasma
Route of administration of tetracyclines:
Oral, injectable, topical
Plasma concentrations of tetracyclines will be highest ____
On an empty stomach
How are water-soluble tetracyclines eliminated?
Distributes to the extracellular fluid compartment. Half metabolized into bile, half excreted into urine
How are lipid-soluble tetracyclines eliminated?
Metabolized in liver, secreted into bile
Mechanisms that lead to tetracycline resistance:
Efflux pumps and ribosomal protective proteins
What proteins inhibit the binding of tetracycline?
Ribosomal protection proteins
