aminoglycosides

Question 1

What are the most frequently prescribe aminoglycosides?

Answer 1

gentamicin, tobramycin, and amikacin

Question 2

What is the MOA of aminoglycosides?

Answer 2

Crosses bacterial membrane, then binds to 30s ribosomal subunit and inhibits protein synthesis. bactericidal

Question 3

What are mechanisms of resistance against aminoglycosides?

Answer 3

Transferase enzyme inactivates aminoglycoside, Impaired entry of aminoglycoside into the cell,or receptor protein on 30S ribosomal subunit may be deleted/altered

Question 4

What is the most common clinical application of aminoglycosides?

Answer 4

treatment of serious infections caused by aerobic gram-negative bacilli including Pseudomonas, Enterobacter, Serratia, Acinetobacter, and Klebsiella.

Question 5

What can aminoglycosides be used with to cover gram positive cocci?

Answer 5

Enterococcus faecalis endocarditis—ampicillin or penicillin + gentamicin or streptomycin.
S. aureus endocarditis—naficillin + gentamicin

Question 6

Describe gentamicin (Garamycin)

Answer 6

most widely used aminoglycoside effective for gram +/- that’s usually used with a beta-lactam.

Question 7

Describe tobramycin (Nebcin)

Answer 7

gram +/- coverage and better Pseudomonas coverage. more $$$ than gentamicin. comes as an inhalable soln for CF

Question 8

Describe Amikacin (Amikin)

Answer 8

used for resistant bacteria, IV/IM

Question 9

Describe streptomycin

Answer 9

2nd line for TB in combo w/other agents. Used with penicillin or ampicillin for Enterococcus faecalis endocarditis or Viridans streptococcus endocarditis. IM

Question 10

Describe Neomycin (Mycifradin)

Answer 10

topical or oral use. bowel prep for surgery w/erythromycin. Pseudomonas and Streptococci tent to be resistant

Question 11

Describe Paromomycin (Humatin)

Answer 11

oral only. for intestinal amebiasis, hepatic coma/encephalopathy.

Question 12

What is the associated risk of aminoglycosides with pregnancy and lactation?

Answer 12

D (there is evidence of human risk, but clinical benefits may outweigh risk). Lactation: aminoglycosides enter breast milk but are not well absorbed orally so they are okay during breastfeeding

Question 13

What is an absolute CI to aminoglycoside use?

Answer 13

Myasthenia gravis- neuromuscular blockade risk too high

Question 14

What are black box warnings of aminoglycosides?

Answer 14

nephrotoxicity, ototoxicity, neurotoxicity, neuromuscular blockade

Question 15

Describe the nephrotoxicity associated with aminoglycosides

Answer 15

Reversible, non-oliguruic renal failure (acute tubular necrosis). Increased risk in elderly, renal dsfxn, dehydration, hypotension, liver disease, use of other nephrotoxins. once daily dosing is less toxic. neomycin, tobramycin, and gentamicin are the most nephrotoxic

Question 16

Describe the ototoxicity associated with aminoglycosides

Answer 16

Vestibular: manifests as vertigo, ataxia, loss of balance, tinnitus. Cochlear: manifests as high frequency hearing loss, deafness is unusual. Often irreversible. Neomycin, kanamycin, amikacin are most ototoxic

Question 17

Describe the neuromuscular blockade associated with aminoglycosides

Answer 17

neuromuscular blockade at very high doses given too fast resulting in respiratory paralysis. reversible by calcium gluconate

Question 18

What are monitoring levels for gentamicin and tobramycin?

Answer 18

Peak – 30 minutes after infusion: 4 – 10 mcg/mL.

Troughs – 30 minutes before infusion: <2 mcg/mL

Question 19

What are monitoring levels of amikacin?

Answer 19

Peak – 30 minutes after infusion: 15 – 30 mcg/mL

Troughs – 30 minutes before infusion: <2 mcg/mL

Question 20

What are drug interactions w/aminoglycosides?

Answer 20

chemo agents, BCG, loop diuretics, neuromuscular blocking agents, cephalosporins