gentamicin

Question 1

ahminoglycosides are primarily excreted …. so impairment has this consequence…

Answer 1

renally
so accumulation can occur in RI - increased risk of ototoxicity and nephrotoxicity

Question 2

in which patients must you frequently monitor serum-amino glycoside conc

Answer 2

in pt with RI

Question 3

monitoring of patients parameters (3)

Answer 3

assess renal function BEFORE starting and DURING treatment
monitor auditory and vestibular function DURING treatment

Question 4

MHRA for all aminoglycosied by injection and when used by ear - increased risk of deafness in pt with mitochonridal mutations

Answer 4

• rare
• consider genetic testing esp in pt needing recurrent or long term treatment, however do not delay urgent treatment
• monitor renal and auditory function and hepatic and laboratory parameters to minimise risk of adverse effects
• pt with known mitochondrial mutations or FHx ototoxicity to inform Dr or pharmacist before using ahminoglycosides

Question 5

there is an increased risk of ….. in pt with …. mutations

Answer 5

deafness with mitochondrial mutations (even if serum levels are within recommended range)

Question 6

gentamicin MHRA advice about potential for histamine related adverse drug with IM, intrathecal or IV use

Answer 6

some batches of gentamicin sulphate API used to manufacture gentamicin may contain higher than expected levels of histamine (residual from manufacturing process)
monitor pt with signs of histamine related adverse reactions
particular caution required in pt taking concomitant drugs known to cause histamine release, in children and in pt with severe RI

Question 7

some batches of gentamicin may contain higher than expected levels of histamine. thus you need to be aware of signs of histamine related adverse reactions e.g.

Answer 7

allergy symptoms
severe - anaphylaxis

Question 8

some batches of gentamicin may contain higher than expected levels of histamine. thus you need to be aware of signs of histamine related adverse reactions. particular caution is requires in the following patients

Answer 8

patients taking concomitant drugs known to cause histamine release, in children, and in patients with severe renal impairment.

Question 9

contraindications for all ahminoglycosides by injection and why

Answer 9

Myasthenia gravis (aminoglycosides may impair neuromuscular transmission)

Question 10

why is it myasthenia gravis contraindicated for all aminoglycoses by injection

Answer 10

AG may impair neuromuscular transmission

Question 11

whenever possible parenteral treatment should not exceed …

Answer 11

7days

Question 12

what are two important side effects to consider with aminoglycoside therapy and who do they most commonly affect?

Answer 12

Ototoxicity and nephrotoxicity
Nephrotoxicity occurs most commonly in patients with renal impairment, who may require reduced doses; monitoring is particularly important in the elderly.

Question 13

therapeutic drug monitoring of gentamicin with IM or IV use in adults. for multiple daily dose regimen, one hour peak serum conc should be ….. and pre-dose (trough) conc should be …..

Answer 13

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

Question 14

therapeutic drug monitoring of gentamicin with IM or IV use in adults. For multiple daily dose regimen in endocarditis, one-hour (‘peak’) serum concentration should be …. and pre dose (trough) conc should be ….

Answer 14

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

Question 15

for multiple daily dose regimen in endocarditis, how often should you measure serum-gentamicin conc?

Answer 15

After 3 or 4 doses, then at least every 3 days and after a dose change (more frequently in renal impairment).

Question 16

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 16

• obesity
• high doses being given
• CF

Question 17

do you need to determine serum aminoglycoside concentrations in the elderly

Answer 17

MUST

Question 18

in patients with normal renal function, how often should you measure serum AG conc?

Answer 18

after 3-4 doses of a multiple daily dose regimen
and after dose change

Question 19

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

Answer 19

• 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 20

what to do in adults if pre-dose (though) is high and post dose (peak) conc is high

Answer 20

If the pre-dose (‘trough’) concentration is high, the interval between doses must be increased.
If the post-dose (‘peak’) concentration is high, the dose must be decreased.

Question 21

can you use AG in pregnancy. when is risk of SE most likely? which drug is it most likely with and which drugs it is least likely with? monitoring requirements?

Answer 21

• risk of auditory of vestibular nerve damage in infant when used in 2nd and 3rd trimesters
• risk is greater with streptomycin
• risk is probably small with gentamicin and tobramycin but their use should be avoided unless essential
• if given in pregnancy, serum-AG conc monitoring is essential!

Question 22

risk of auditory or vestibular nerve damage in the infant with AG are used in 2nd and 3rd trimesters of pregnancy. risk is greatest with this drug … and the risk if probably very small with these drugs …… but their use should be avoided unless essential

Answer 22

greatest risk with streptomycin
probably low risk with gentamicin and tobramycin

Question 23

for streptomycin, side effects increase after a cumulative dose of …..g which should only be exceeded in exceptional circumstances

Answer 23

100g

Question 24

streptomycin : one hour (peak) conc should be …. and the pre dose (trough) concentration should be …. (and in RI and in those over 50)

Answer 24

One-hour (‘peak’) concentration should be 15–40 mg/litre
Pre-dose (‘trough’) concentration should be less than 5 mg/litre (less than 1 mg/litre in renal impairment or in those over 50 years).

Question 25

would you use ideal weight or actual weight for obese pt to calculate parenteral dose? and what do you do about monitoring

Answer 25

To avoid excessive dosage in obese patients, use ideal weight for height to calculate parenteral dose and monitor serum-tobramycin concentration closely.
WITH IM OR IV USE

Question 26

tobramycin - monitor concentrations in pt with known or suspected signs of auditory dysfunction. if ototoxicity develops, discontinue until

Answer 26

until serum concentration falls below 2 mg/litre.

Question 27

gentamicin has broad spectrum but is inactive against

Answer 27

anaerobes

Question 28

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

Answer 28

a penicillin or metronidazole or both

Question 29

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

Answer 29

streptomycin

Question 30

MOA of AG

Answer 30

inhibit protein synthesis by binding to 30S ribosomal subunit