CLASSES OF ABX: AMINOGLYCOSIDES

Question 1

Aminoglycoside examples

Answer 1

Amikacin
Gentamicin
Neomycin
Streptomycin
Tobramycin

Question 2

MOA

Answer 2

• Irreversibly bind to 30s ribosomes
• Inhibit protein synthesis

Question 3

What organisms are ahminoglycosides active against?

Answer 3

SOME Gram-POSITIVE
MANY Gram-NEGATIVE organisms.

Question 4

What aminoglycosides are active against Pseudomonas aeruginosa?

Answer 4

Amikacin, gentamicin and tobramycin

Question 5

How are AG administered

Answer 5

• via injection: OD or multiple (2-3 divided doses)
• not absorbed from the gut

Question 6

Which AG is not administered via injection?

Answer 6

Neomycin
- too toxic
- PO/ topical

Question 7

Which AG can be absorbed via nebuliser/ inhalation poweder?

Answer 7

Tobramycin
- via injection, nebuliser, inhalation powder

Question 8

What aminoglycoside is active against Mycobacterium tuberculosis?

Answer 8

Streptomycin

Question 9

Gentamicin has broad spectrum but is inactive against

Answer 9

anaerobes

Question 10

when gentamicin is used as blind therapy of undiagnosed serious infections it is usually given in conjunction with…

Answer 10

a penicillin or metronidazole or both

Question 11

a patient has gentamicin resistant enteroccal endocarditis. which AG do you give instead

Answer 11

streptomycin

Question 12

Indication

Answer 12

• In combination therapy for:
  o Endocarditis
  o Septicaemia
  o meningitis
  o other CNS infections
• biliary-tract infection
• prostatitis
• pneumonia.

Question 13

Side effects

Answer 13

• OTO/NEPHROTOXICITY
• N+V
• AAC
• Peripheral neuropathy
• Electrolyte disturbances.

Question 14

Contraindication

Answer 14

• Avoid in pregnancy
• Obese patients
• Avoid using in conjunction with ototoxic drugs
• Avoid using in conjunction with drugs that cause renal impairment

Question 15

Contraindications for all ahminoglycosides by injection

Answer 15

Myasthenia gravis (aminoglycosides may impair neuromuscular transmission)

Question 16

why is it myasthenia gravis contraindicated for all aminoglycosides by injection

Answer 16

AG may impair neuromuscular transmission

Question 17

Aminoglycosides and pregnancy

Answer 17

• Auditory or vestibular nerve damage in 2nd and 3rd trimesters
• Greater risk with streptomycin
• Less risk with gentamicin and tobramycin but their use should be avoided unless essential
• Monitor serum conc if you do give it

Question 18

Aminoglycosides and obese patients

Answer 18

o Use ideal body weight
o Based on height to calculate parenteral dose

Question 19

What are examples of other ototoxic drugs

Answer 19

o e.g. cisplatin
o loop diuretics (furosemide, spironolactone, bumetanide, torasemide)
o vancomycin
o vinca alkaloids (vinblastine, vincristince, vindesine, vinfluine

Question 20

therapeutic drug monitoring of gentamicin - serum amino glycoside conc should be measured in all pt receiving parenteral aminoglycosides and MUST be determined in the following pt (3)

Answer 20

obesity
high doses being given
CF
elderly

Question 21

How often should you monitor serum-aminoglycoside concentrations

Answer 21

• after 3 or 4 doses, then every 3 days
• after a dose change

Question 22

When should you monitor renal function

Answer 22

Assess renal function BEFORE starting and DURING treatment

Monitor auditory and vestibular function DURING treatment

Question 23

WHEN (not how often) should you take blood samples of serum AG conc for multiple daily dose regimens

Answer 23

to get peak conc: take blood samples ~1h after IM or IV admin

to get trough conc: take blood samples just before next dose is due

Question 24

Multiple daily dose regimen (peak)

Answer 24

5-10mg/L

Question 25

Multiple daily dose serum concentration (trough)

Answer 25

Less than or equal to 2mg/L

Question 26

Multiple daily dose in endocarditis (peak)

Answer 26

3-5mg/L

Question 27

Multiple daily dose in endocarditis (trough)

Answer 27

Less than 1mg/L

Question 28

Multiple daily dose regimen

Answer 28

one-hour (‘peak’) serum concentration should be 5–10 mg/litre;
pre-dose (‘trough’) concentration should be less or equal too 2 mg/litre.

Question 29

Multiple daily dose in endocarditis

Answer 29

one-hour (‘peak’) serum concentration should be 3–5 mg/litre
pre-dose (‘trough’) concentration should be less than 1 mg/litre.

Question 30

Why is the dose lower in endocarditis

Answer 30

endocarditis is lower because we co-prescribe with other antibiotics

Question 31

What do we do if the trough is too high?

Answer 31

Increase dose interval

Question 32

What do we do if the peak is too high?

Answer 32

Decrease dose

Question 33

What do we do if their is renal impairment?

Answer 33

Increase dose interval

Question 34

What do we do in severe renal impairment?

Answer 34

Decrease dose

Question 35

whenever possible parenteral treatment should not exceed …

Answer 35

7 days

Question 36

Aminoglycosides for systemic infections

Answer 36

injections for systemic infections
neomycin is used to reduce bacterial population of the colon before bowel surgery or in hepatic failure

Question 37

How are aminoglycosides primarily excreted?

Answer 37

Renally
SO accumulation can occur in RI - increased risk of ototoxicity and nephrotoxicity

Question 38

What is the MHRA warning with regards to histamine and Gentamicin?

Answer 38

• Some batches of gentamicin may contain higher then expected histamine
• MHRA have asked to monitor for signs of histamine-related ADR’s in patients taking drugs known to increase histamine release or whom are severely renally impaired

Question 39

What is the MHRA warning regarding
Aminoglycosides and mitochondrial mutations?

Answer 39

• Gentamicin, amikacin, tobramycin, and neomycin given by injection all increase risk of deafness in patients with mitochondrial mutations
• Gentamicin given by ear drops can also increase the risk