Aminoglycosides and Tetracyclines

Question 1

What type of drug is Gentamicin?

Answer 1

Aminoglycoside

Question 2

What type of drug is tobramycin:

Answer 2

Aminoglycoside

Question 3

What type of drug is amikacin?

Answer 3

Aminoglycoside

Question 4

MOA of aminoglycoside

Answer 4

Binds irreversibly to bacterial ribosomes which inhibits protein synthesis

Question 5

What is the basis for protein synthesis?

Answer 5

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

Question 6

What does gentamicin target?

Answer 6

Gram neg bacteria, gram pos staphylococci, gram pos mycoplasma

Question 7

What is tobramycin used to treat & how?

Answer 7

Used topically to treat bacteria that is resistant to gentamicin

Question 8

The 70S ribosome of a bacterium is comprised of ____

Answer 8

A 30S subunit and a 50S subunit

Question 9

Two mechanisms by which bacterial resistance to aminoglycosides can occur:

Answer 9

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

Question 10

Aminoglycosides work synergistically with drugs that interfere with _____

Answer 10

Cell wall

Question 11

Bioavailability of aminoglycosides:

Answer 11

Very low oral absorption, must be given parenterally

Question 12

Adverse effects of aminoglycosides:

Answer 12

Nephrotoxicity, ototoxicity

Question 13

How can nephrotoxicity be minimized following aminoglycoside treatment?

Answer 13

Allowing a washout period each day
- A single daily dose and allowing concentrations to fall for remainder of day

Question 14

What is targeted by aminoglycoside-induced ototoxicity?

Answer 14

Damage to cranial nerves (CN VIII) and hair cells in the cochlea and vestibular apparatus

Question 15

Tetracyclines are mainly used to treat ____

Answer 15

Atypical bacteria (neither gram pos or neg)

Question 16

Where do tetracyclines bind?

Answer 16

30S subunit on ribosomes

Question 17

MOA of tetracyclines:

Answer 17

Prevent binding of aminoacyl-tRNA through allosterically binding to the ribosome
This binding is irreversible, leading to bacteriostatic effect

Question 18

Atypical bacterial infections examples:

Answer 18

Rickettsia, chlamydia, mycoplasma

Question 19

Route of administration of tetracyclines:

Answer 19

Oral, injectable, topical

Question 20

Plasma concentrations of tetracyclines will be highest ____

Answer 20

On an empty stomach

Question 21

How are water-soluble tetracyclines eliminated?

Answer 21

Distributes to the extracellular fluid compartment. Half metabolized into bile, half excreted into urine

Question 22

How are lipid-soluble tetracyclines eliminated?

Answer 22

Metabolized in liver, secreted into bile

Question 23

Mechanisms that lead to tetracycline resistance:

Answer 23

Efflux pumps and ribosomal protective proteins

Question 24

What proteins inhibit the binding of tetracycline?

Answer 24

Ribosomal protection proteins

Question 25

Adverse effects of tetracyclines:

Answer 25

Discoloured teeth, photosensitization, renal damage, bone growth

Question 26

Three main non-antimicrobial effects of tetracycline:

Answer 26

1. Inhibition of MMPs
2. Anti-inflammatory effects
3. Role in scavenging of ROS

Question 27

Which tetracyclines affect ROS production?

Answer 27

Doxycycline & minocycline

Question 28

What class is tigecycline?

Answer 28

Glycylcycline

Question 29

What effect on bacteria does tigecycline have?

Answer 29

Bacteriostatic