Amikacin prescribing guidance
Amikacin is an
aminoglycoside antibiotic active against some Gram-positive organisms,
principally Staphylococcus aureus
(including some MRSA), and many Gram-negative organisms including Psuedomonas aeruginosa. It is primarily
indicated for the treatment of serious infections caused by gentamicin-resistant
Gram-negative bacilli. Amikacin should only be initiated after consultation
with a microbiologist.
is contraindicated in myasthenia gravis and in patients with a known allergy to
aminoglycosides. It should be used in caution where there is pre-existing renal
insufficiency or hearing/vestibular damage – baseline audiometry can assist in
identifying this. Patients should be well hydrated during treatment with
amikacin. The maximum licensed cumulative dose per course is 15g; exceeding
this increases the risk of ototoxicity and audiological monitoring is
clearance, volume of distribution and half-life of all aminoglycosides are
similar and the same pharmacokinetic model can be used for each agent. The
pharmacy department’s ‘gentamicin calculator’ is therefore applicable to
amikacin. As aminoglycosides distribute poorly into the adipose tissue, using
true body weight in obese patients may result in an overdose:
underweight use actual body weight
<20% overweight use actual body weight
- if >20% overweight use adjusted body weight
weight = ideal body weight + 0.4(actual body weight – ideal body weight)
weight = (height in inches over 5 foot x 2.3) + 50 for males/45 for females]
interval (ONCE daily) dosing regime
patients are suitable for ONCE daily amikacin dosing
eCrCl >30mL/min and <65 years old, prescribe 15mg/Kg ONCE daily
(maximum dose 1.5g). Trough level before second dose.
- If eCrCl <30mL/min or >65
years old, prescribe 15mg/Kg STAT. Dosing interval may need to be increased; please refer to pharmacy for advice.
multiple daily dose regimes
should not be recommended as once daily dosing has a greater safety profile
intravenously in 100mL 0.9% sodium chloride or 5% glucose over 20- 30 minutes.
exhibits concentration-dependent killing followed by a post-antibiotic period
of supressed bacterial growth. Peak level monitoring is NOT routinely necessary in patients receiving once daily amikacin
although it may be desirable in certain population groups (e.g. critical care
patients). In these cases microbiology will advise on a target level as there
is no universally agreed target peak. Maximum bactericidal effect is seen when
serum amikacin levels exceed 10 times the minimum inhibitory concentration
(MIC). As a general guide, the MIC breakpoint for the more problematic bacteria
(including Pseudomonas and Enterobacteriaceae) is 8mg/L. The Bristol Centre for
Antimicrobial Research and Evaluation recommends a target peak of >50mg/L. However for ongoing prescriptions of
amikacin, microbiology should provide advice on MIC of organism and target
interval (ONCE daily) regimes
a trough level prior to the second dose; aim for <5mg/L
levels’ can also be used following pharmacy advice. The levels will need to be followed
up within 24 hours to help determine ongoing dose/if appropriate to continue.
with CrCl <30ml/min should have their levels
reviewed before second dose is administered.
peak level monitoring is NOT
normally necessary (but see above)
- Ensure patient receives daily U&Es whilst on amikacin
should be taken in a red topped plain
serum tube and for Aintree samples the laboratory informed that an amikacin
level (s) is urgently required.
levels can now be ordered on ICE and on EPMA in the same way as gentamicin.
Levels should be monitored every 3 - 5 days.
can be contacted on extension Aintree site
3241, Royal site 4253