Aminoglycosides

Question 1

What are the main Aminoglycosides?

Answer 1

**Gentamicin
Tobramycin
Neomycin (Neosporin)

Question 2

What are the Aminoglycosides mechanisms of action?

Answer 2

• Block initiation of protein synthesis
• Blocks further translation and elicits premature termination
• Incorporation of incorrect amino acid

Basically revolves around how put together protein chains

Question 3

What is Gentamicin & Tobramycin used for?

Answer 3

• Available as IV or IM
• pneumonia, meningitis, bacterial endocarditis, sepsis,
  -Susceptible bacterial infections, normally gram-negative including Pseudomonas, Proteus, Serratia
  Bone infections
  Skin and soft tissue
  Abdominal and urinary tract infections

Question 4

What is Neomycin used for?

Answer 4

• Broad spectrum including gram-negative and gram-positive
• Orally: GI tract sterilization, diarrhea caused by E. coli, treatment of hepatic encephalopathy
• Topically: gram-negative and select gram-positive bacteria

Question 5

What are the Absorption characteristics of the Aminoglycosides?

Answer 5

Poor absorption from GI tract

Rapid absorption from muscle

Question 6

What are the Distributioncharacteristics of the Aminoglycosides?

Answer 6

Poor cell penetration except renal cortex and lymph of inner ear

Question 7

What are the Elimination characteristics of the Aminoglycosides?

Answer 7

Almost entirely renal

Half-life at 2 to 3 hours

Question 8

What do the Aminoglycosides kill?

Answer 8

• Rapidly bactericidal
• Aerobic gram-negative bacilli
  - Tobramycin and gentamicin roughly equivalent in activity
  
  • Tobramycin may have better activity against Pseudomonas aeruginosa and some Proteus
  • Gentamicin better against Serratia
    - Gentamicin resistance

Question 9

What are the dosing patterns for the Aminoglycosides?

Answer 9

• Once a day dosing versus 3 times a day
  - Equal efficacy
  - Reduced toxicity
  - Ease of administration
  - Lower cost
• Blood level determination
  - Trough level: Better do before day 4 to see if kidney function is ok. If levels rising then you have toxicity.

Question 10

What are possible side effects of the Aminoglycosides?

Answer 10

• Ototoxicity
  - Vestibular and auditory dysfunction
  - Streptomycin and gentamicin- vestibular
  - Neomycin and amikacin- auditory
  - Tobramycin- equal toxicity
• Nephrotoxicity
  - Related to tubular cell damage and glomerular dysfunction
  - Neomycin the worst; streptomycin the least

Question 11

Prescription for Gentamicin (HOUR based dose) ?

Answer 11

1.3 to 1.7 mg/kg
IVPB
every eight (8) hours

Question 12

Prescription for Gentamicin (DAY based dose) ?

Answer 12

5 to 7 mg/kg
IVPB
once a day