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Antibiotics > Aminoglycosides > Flashcards

Aminoglycosides Flashcards

1
Q

What is the mechanism of action for aminoglycosides?

A
  • Aminoglycoside binds to outer membrane of cell, resulting in a rearrangement of LPS.
  • Uptake is energy dependent (slow phase and rapid phase); the source of energy is an electrochemical gradient (this gradient is decreased in an anaerobic environment).
  • Once across the membrane the drug is irreversibly trapped into bacteria cytoplasm (very high intracellular concentrations).
  • Aminoglycoside then binds to 30 S and 50 S ribosomal subunit, resulting in decreased protein synthesis and increased misreading of mRNA.
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2
Q

Are Aminoglycosides Bactericidal or Bacteristatic?

A

Bactericidal

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3
Q

T/F
Aminoglycosides (along with fluoroquinolones) exhibit Postantibiotic Effect.

T/F
Aminoglycosides exhibit ”Concentration dependent killing.”

A

TRUE

TRUE

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4
Q

Why are Amikacin, Gentamycin, and Tobramycin all given IV but Neomycin can be taken PO?

A

Generally, Aminoglycosides very poorly absorbed from GI Tract

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5
Q

Why can Aminoglycosides often be used for monotherapy in the instance of UTIs?

A

99% of the drug unchanged by glomerular filtration

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6
Q

Describe aminoglycoside distribution to the lung and inflamed meninges?

A

40% to lung

20% to CSF (less when not inflamed; better distribution in neonates thought due to immature blood brain barrier)

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7
Q

Do aminoglycosides undergo hepatic or renal elimination?

A

Renal Excretion as active drug (good for UTIs)

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8
Q

Why do you need to be careful in dosing aminoglycosides in patients who are:

Elderly
Critically Ill (dehydrated or volume overload)
Renal Disease
Cachexia/Malnourished

A

Decreased Vd and Ke
Change in Vd
Decreased Ke; Change in Vd
Decreased Vd & creatinine production

(I say don’t memorize)

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9
Q

What are the common Aminoglycosides?

A

Tobramycin
Amikacin
Gentamycin
Neomycin

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10
Q

Why isn’t Amikacin used as often as Tobramycin, Gentamycin, or Neomycin?

A

Closest place that runs Amikacin levels is North Carolina

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11
Q

What adverse reactions are associated with Aminoglycoside use?

A
  • Thrombophlebitis
  • Nephrotoxicity (20% of patients!)
  • Ototoxicity
  • Neuromuscular Block (rare, provide 2g Ca2+ if happens)
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12
Q

Really high PEAKS in aminoglycoside levels cause?

Really high TROUGHS in aminoglycoside levels cause?

A

OTOTOXICITY

NEPHROTOXICITY

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13
Q

What bugs are covered by Aminoglycosides?

A

GRAM NEGATIVES

  • Morganella
  • Haemophilus
  • Providencia
  • Proteus Mirabilis
  • PEK
  • SPACE
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14
Q

Which aminoglycoside covers the least bugs of them all?

Which bugs doesn’t it cover

A

Kanamycin

Providencia
Acinetobacter
Enterobacter

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15
Q

How would you cover enterococcus using aminoglycosides?

A

must do combo therapy for synergy; common combination is Ampicillin+Gentamycin

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16
Q

What specific aminoglycoside would you use to treat Tuberculosis?

What specific aminoglycoside would you use to treat Brucellosis?

A

Streptomycin

Gentomycin

17
Q

Why use Neomycin for prophylaxis in instance of colorectal surgery?

Why use Neomycin in instance of hepatic coma?

Why use Neomycin in instance of hyperlipidemia?

A

suppresses intestinal flora

decrease amount of ammonia forming bacteria

decrease cholesterol absorption

18
Q

T/F
Large daily doses may be equally effective as smaller multiple daily dosing with lower toxicity.

T/F
Low serum concentrations allow the kidney cells to process drug and thereby reduce effects of accumulation.

What principle allows this to happen?

A

TRUE

TRUE

Post Antibiotic Effect

19
Q

Why is the Hartford Nomogram used for amioglycosides?

How does it work?

A

substantial variations exist in concentrations achieved compared to predicted values

• 7mg/kg first dose (Less if CrCl is

20
Q

T/F
Aminoglycosides distribute to lung last.

T/F
Prolonged exposure to Aminoglycosides is correlated with spike in nephrotoxicity occurrance.

A

TRUE (higher peak values needed to achieve theraputic index for pneumonias)

TRUE

21
Q

Troughs should be no higher than what to best avoid Nephrotoxicity?

A

Less than 2 mcg/ml

Antibiotics (25 decks)

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