Aminoglycoside & Vancomycin Dosing & Monitoring (Adults)
Amikacin Dosing & Monitoring
Amikacin Dosing & Monitoring
- Reserve antimicrobial : Effective use of amikacin is complex and should be discussed with Microbiology or Infectious Diseases. The following is provided for guidance.
- In general, treatment should be reviewed within 24 hours, and daily thereafter by consultant/specialist registrar. Courses should not usually exceed 3 days. The recommended maximum daily dose is 1.5g; the maximum cumulative dose should not exceed 15g per treatment course.
- In multi-drug resistant TB (on Infectious Diseases or Respiratory or Microbiology advice), see IV guideline on MedinfoGalway for dosing and monitoring guidance.
- Once daily dosing of amikacin is recommended for most patients. Discuss patients with renal impairment with creatnine clearance less than 30ml/minute with Microbiology or Infectious Diseases
- Amikacin is potentially nephrotoxic & ototoxic; monitor amikacin levels closely.
- Prolonged duration of treatment and co-administration of nephrotoxins (e.g. diuretics, NSAIDs, vancomycin) increases risk of toxicity and should be avoided where possible.
- The responsible clinical team must check reported amikacin levels regularly and adjust dosing if required. The laboratory does NOT alert teams of out of range results. Levels must arrive in the microbiology laboratory by 11am Monday to Friday and by 10am Saturday (not processed on Sunday) to be analysed on the day of receipt.
- Do NOT hold dose while waiting for level to be reported, in a patient less than 65 years with good renal function (creatinine clearance greater than 80ml/minute) and with good urine output.
- However, in a patient over 65 years, or with abnormal renal function (creatinine clearance less than 80ml/minute), it is generally preferable to await the result of the first amikacin level (i.e. before the second dose) before giving the next dose. If the level is less than 5 mg/L and renal function is stable it is not necessary to routinely hold subsequent doses pending levels.
Table 1: Once Daily Amikacin Dosing Guidelines (Except TB) |
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Step 1 |
Cautions/ Discuss with Micro or ID or Pharmacy |
Cautions: Age ≥65, renal impairment (CrCl <80ml/min), obesity (use adjusted dosing weight), other nephrotoxins Patients with severe renal impairment (CrCl <30ml/min) should be discussed with Microbiology or Infectious Diseases TB: See IV guideline on MedinfoGalway for guidance on dosing & monitoring in TB patients |
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Step 2 |
Calculate patient’s ideal body weight (IBW): Height required |
Ideal Body Weight (IBW) (kg) = Male: 50kg + (2.3 x inches over 5 feet) OR 50kg + (0.9 x cm over 152cm) Female: 45.5kg + (2.3 x inches over 5 feet) OR 45.5kg + (0.9 x cm over 152cm) |
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Step 3 |
Dosing Weight/ Obesity Adjustment: Weight required |
Obesity adjustment : Obese patient: If actual body weight exceeds IBW by ≥20%, calculate Adjusted Dosing Weight: Adjusted Dosing Weight (kg) = Ideal Body Weight + 0.4 x (Actual Body Weight – Ideal Body Weight) Non-obese patient: Use actual body weight to dose amikacin. |
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Step 4 |
Estimate renal function: Patient age, weight, height, & serum creatinine required |
Must use creatinine clearance ( not eGFR) to dose amikacin. Calculate the patient’s estimated creatinine clearance using Cockcroft & Gault equation. Neither creatinine clearance nor eGFR provide a perfect marker of renal function, particularly if rapidly changing renal function. |
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Step 5 |
Select a dose based on renal function and weight. If obese use Adjusted Dosing Weight; If non-obese use Actual Body Weight (See Step 3). |
|||
CrCl (ml/min) |
Dose: round to nearest 50mg |
|||
Greater than 80 |
15mg per kg IV (up to a max of 1.5g) |
every 24 hours |
||
60 to 79 |
12mg per kg IV (up to a max of 1.5g) |
every 24 hours |
||
40 to 59 |
7.5mg per kg IV (up to a max of 1.5g) |
every 24 hours |
||
30 to 39 |
4mg per kg IV (up to a max of 1.5g) |
every 24 hours |
||
less than 30 |
Avoid if possible. If essential, give 3 to 4mg per kg IV (up to a max of 320mg), one dose only |
Check level at 24 hours, discuss need for second dose with Micro/ID |
||
Intermittent haemodialysis: 5mg/kg (up to a max of 400mg) with each dialysis. Give dose post-dialysis. |
Table 2: Once Daily Amikacin Administration & Monitoring Guidelines |
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Administration |
|
Monitoring |
Discuss with pharmacy for advice on monitoring in TB patients. The following applies to indications other than TB:
|
Table 3: Interpretation of Pre-dose Levels for Once Daily Amikacin |
|
Target pre-dose (trough) level is <5mg/L |
|
Level |
Advice |
<5 mg/L |
|
≥5 mg/L |
|
Gentamicin Dosing & Monitoring
Gentamicin Dosing & Monitoring
- Effective use of gentamicin is complex and should normally be discussed with Microbiology or Infectious Diseases. The following is provided for guidance.
- In general, treatment should be reviewed within 24 hours, and daily thereafter by consultant/specialist registrar. Courses should not usually exceed 3 days.
- Once daily dosing of gentamicin is recommended for most patients. Discuss patients with renal impairment with creatinine clearance less than 30ml/minute with Microbiology/Infectious Diseases.
- This once daily gentamicin regimen is not recommended for endocarditis, as an alternative dosing regimen is recommended - see Table 4.
- Gentamicin is potentially nephrotoxic & ototoxic; monitor gentamicin levels closely.
- Prolonged duration of treatment and co-administration of nephrotoxins (e.g. diuretics, NSAIDs, vancomycin) increases risk of toxicity and should be avoided where possible.
- The responsible clinical team must check reported gentamicin levels regularly and adjust dosing if required. The laboratory does NOT alert teams of out of range results. Levels are processed once daily and must arrive in the biochemistry laboratory by 11am to be analysed on the day of receipt.
- Do NOT hold dose while waiting for level to be reported, in a patient less than 65 years with good renal function (creatinine clearance greater than 80ml/minute) and with good urine output.
- However, in a patient over 65 years, or with abnormal renal function (creatinine clearance less than 80ml/minute), it is generally preferable to await the result of the first gentamicin level (i.e. before the second dose) before giving the next dose. If the level is less than 1mg/L and renal function is stable it is not necessary to routinely hold subsequent doses pending levels.
Table 1: Once Daily Gentamicin Dosing Guidelines |
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Use the Gentamicin Dosing Calculator in the GAPP App to calculate Once Daily Gentamicin dose. Details provided below for background information.The calculator will not produce reliable results in patients who are anuric or in acute renal failure. Advice should be sought from your ward pharmacist or Microbiology or Infectious Diseases. Do NOT use the calculator for patients with infective endocarditis, as an alternative dosing regimen is recommended -see Table 4 |
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Step 1 |
Cautions/ Discuss with Micro or ID |
|
||
Step 2 |
Calculate patient’s ideal body weight (IBW): Height required |
Ideal Body Weight (IBW) (kg) = Male: 50kg + (2.3 x inches over 5 feet) OR 50kg + (0.9 x cm over 152cm) Female: 45.5kg + (2.3 x inches over 5 feet) OR 45.5kg + (0.9 x cm over 152cm) |
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Step 3 |
Dosing Weight/ Obesity Adjustment: Weight required |
Obesity adjustment :
Adjusted Dosing Weight (kg) = Ideal Body Weight + 0.4 x (Actual Body Weight – Ideal Body Weight)
|
||
Step 4 |
Estimate renal function: Patient age, weight, height, & serum creatinine required |
|
||
Step 5 |
Select a dose based on renal function and weight. If obese use Adjusted Dosing Weight; If non-obese use Actual Body Weight (See Step 3) |
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CrCl (ml/min) |
Dose: round to nearest multiple of 40mg NB: Doses above 400mg once daily rarely needed |
|||
Greater than 80 |
5mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
60 to 79 |
4mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
40 to 59 |
3.5mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
30 to 39 |
2.5mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
less than 30 |
Avoid if possible. If essential, give 2mg per kg IV (up to a max of 160mg), one dose only |
Check level at 24 hours, discuss need for second dose with Micro or ID |
||
Intermittent haemodialysis: See Haemodialysis Dosing Guidelines |
Table 2: Once Daily Gentamicin Administration & Monitoring Guidelines
|
|
Administration
|
· By IV infusion in 50 to 100ml of NaCl 0.9% over 30 minutes. See IV administration guide on ward or pharmacy internet http://medinfogalway/ivguides
·
Give first dose
immediately.
|
Monitoring
|
·
Measure
pre-dose
(trough) levels only.
· The first pre-dose level should be taken within 1 hour before the 2nd dose is due. · Document on request form date and time sample was taken and date and time of last dose.
·
If the level is less than 1mg/L, re-check pre-dose levels
twice per week thereafter, or more often
if impaired or rapidly changing renal function, haemodynamically unstable, elderly, or on diuretic therapy
·
Note that
monitoring of renal function
in addition to monitoring of aminoglycoside levels is important as
toxicity
may occur in patients in whom the aminoglycoside levels have never exceeded the acceptable range.
·
With respect to ototoxicity, vestibular disturbance (vertigo, ataxia) often precedes disturbance of hearing and should not be discounted because the patient has levels within the acceptable range.
|
Table 3: Interpretation of Pre-dose Levels for Once Daily Gentamicin
|
|
Target pre-dose (trough) level is <1mg/L
|
|
Level
|
Advice
|
<1mg/L
|
1.
Is gentamicin
still needed?
2.
Is patient responding clinically?
3. Continue same dose if renal function stable but if renal function is changing, recalculate dose with current creatinine 4. Check level in 3 days ( or more often if impaired or rapidly changing renal function, haemodynamically unstable, elderly, or on diuretic therapy) |
≥1mg/L
|
1.
Is gentamicin still needed?
2.
Is it a true pre-dose trough level (taken within one hour before dose)?
3.
Where was sample taken from? (falsely high levels can occur if taken from same line used to give gentamicin).
4.
Is dose correct for weight & renal function?
5.
Is renal function stable?
6.
Dose adjustment required -
contact Microbiology or Infectious Diseases or Pharmacy to discuss on a case-by-case basis.
|
Table 4: Multiple Daily Gentamicin Dosing Guidelines - for Treatment of Endocarditis and Synergy Only
|
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Discussion with Microbiology or Infectious diseases recommended
Other than for endocarditis and synergy, multiple daily dosing of gentamicin is rarely indicated. Once the causative organism has been identified in infective endocarditis, an alternative gentamicin dosing regimen may be indicated on consultation with Microbiology or Infectious Diseases.
|
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Dose
CrCl >70ml/min
|
Dose – renal impairment
|
Recommended range for levels
|
Timing and frequency of levels
|
1mg/kg
(maximum 80mg)
every 8 to 12 hours depending on renal function and age
|
Contact Microbiology or Infectious Diseases for advice
|
Pre-dose :
<1mg/L
Post-dose:
3 to 5 mg/L
|
·
Take first pre-dose (trough) level within one hour before 3
rd
/4
th
dose
·
Take first post-dose (peak) level one hour after 3
rd
/4
th
dose
·
Repeat pre-dose (trough) level every 3 days or more often if high risk of accumulation
·
Post-dose (peak) levels need only be taken once weekly from week two onwards
·
Adjust dose according to levels
·
Monitor renal function
·
Contact Microbiology or Infectious Diseases for further advice
|
Tobramycin Dosing & Monitoring
Tobramycin Dosing & Monitoring
- Effective use of tobramycin is complex and should be discussed with Microbiology or Infectious Diseases. The following is provided for guidance.
- In general, treatment should be reviewed within 24 hours, and daily thereafter by consultant/specialist registrar. Courses should not usually exceed 3 days, except in cystic fibrosis.
- Once daily dosing of tobramycin is recommended for most patients. Discuss patients with renal impairment with creatinine clearance less than 30ml/minute with Microbiology/Infectious Diseases.
- Tobramycin is potentially nephrotoxic & ototoxic; monitor tobramycin levels closely.
- Prolonged duration of treatment and co-administration of nephrotoxins (e.g. diuretics, NSAIDs, vancomycin) increases risk of toxicity and should be avoided where possible.
- The responsible clinical team must check reported tobramycin levels regularly and adjust dosing if required. The laboratory does NOT alert teams of out of range results. Levels must arrive in the microbiology laboratory by 11am Monday to Friday and by 10am Saturday (not processed on Sunday) to be analysed on the day of receipt.
- Do NOT hold dose while waiting for level to be reported, in a patient less than 65 years with good renal function (creatinine clearance greater than 80ml/minute) and with good urine output.
- However, in a patient over 65 years, or with abnormal renal function (creatinine clearance less than 80ml/minute), it is generally preferable to await the result of the first tobramycin level (i.e. before the second dose) before giving the next dose. If the level is less than 1mg/L and renal function is stable it is not necessary to routinely hold subsequent doses pending levels.
Table 1: Once Daily Tobramycin Dosing Guidelines (Cystic Fibrosis only) |
|
Dose (Cystic Fibrosis only)
|
·
10mg/kg (if renal function is normal) as a single dose every 24 hours, up to a maximum of 700mg in adults (660mg in children less than 18 years)
|
Obesity
|
·
If actual body weight exceeds ideal body weight by
≥ 2
0%, an adjusted dosing weight should be used to calculate the dose
|
Renal Impairment
|
·
Contact Microbiology or Infectious Diseases for advice
|
Table 2: Once Daily Tobramycin Dosing Guidelines (other than Cystic Fibrosis) |
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Use the Tobramycin Dosing Calculator in the GAPP App to calculate Once Daily Tobramycin dose in non-CF patients. Details provided below for background information. The calculator will not produce reliable results in patients who are anuric or in acute renal failure. Advice should be sought from your ward pharmacist or Microbiology or Infectious Diseases. Do NOT use the calculator for patients with Cystic Fibrosis, as an alternative dosing regimen is recommended - see Table 1 above |
||||
Step 1 |
Cautions/ Discuss with Micro or ID |
|
||
Step 2 |
Calculate patient’s ideal body weight (IBW): Height required |
Ideal Body Weight (IBW) (kg) = Male: 50kg + (2.3 x inches over 5 feet) OR 50kg + (0.9 x cm over 152cm) Female: 45.5kg + (2.3 x inches over 5 feet) OR 45.5kg + (0.9 x cm over 152cm) |
||
Step 3 |
Dosing Weight/ Obesity Adjustment: Weight required |
Obesity adjustment :
Adjusted Dosing Weight (kg) = Ideal Body Weight + 0.4 x (Actual Body Weight – Ideal Body Weight)
|
||
Step 4 |
Estimate renal function: Patient age, weight, height, & serum creatinine required |
|
||
Step 5 |
Select a dose based on renal function and weight. If obese use Adjusted Dosing Weight; If non-obese use Actual Body Weight (See Step 3). Do NOT use this table for patients with Cystic Fibrosis |
|||
CrCl (ml/min) |
Dose: round to nearest multiple of 40mg NB: Doses above 400 mg once daily rarely needed |
|||
Greater than 80 |
5mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
60 to 79 |
4mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
40 to 59 |
3.5mg per kg IV (up to a max of 400mg) |
every 24 hours |
||
30 to 39 | 2.5mg per kg IV (up to a max of 400mg) | every 24 hours | ||
less than 30 |
Avoid if possible. If essential, give 2mg per kg IV (up to a max of 160mg), one dose only |
Check level at 24 hours, discuss need for second dose with Micro or ID |
||
Intermittent haemodialysis: 1mg/kg (up to a maximum of 80mg) with each dialysis. Give dose post-dialysis. |
Table 3: Once Daily Tobramycin Administration & Monitoring Guidelines
|
|
Administration
|
· By IV infusion in 50 to 100ml of NaCl 0.9% or Glucose 5% over 20 to 60 minutes. See IV administration guide on ward or pharmacy internet http://medinfogalway.ie/ivguides
· Give first dose
immediately.
|
Monitoring
|
· Measure
pre-dose
(trough) levels only.
· The first pre-dose level should be taken within 1 hour before the 2 nd dose is due.
· Document on request form date and time sample was taken and
date and time of last dose.
· If the level isless than 1mg/L, re-check pre-dose levels
twice per week thereafter (once weekly in cystic fibrosis patients), or more often
if impaired or rapidly changing renal function, haemodynamically unstable, elderly, or on diuretic therapy
· Note that
monitoring of renal function
in addition to monitoring of aminoglycoside levels is important as
toxicity
may occur in patients in whom the aminoglycoside levels have never exceeded the acceptable range.
· With respect to ototoxicity, vestibular disturbance (vertigo, ataxia) often precedes disturbance of hearing and should not be discounted because the patient has levels within the acceptable range.
|
Table 4: Interpretation of Pre-dose Levels for Once Daily Tobramycin
|
|
Target pre-dose (trough) level is <1mg/L
|
|
Level
|
Advice
|
<1 mg/L
|
1.
Is tobramycin
still needed?
2.
Is patient responding clinically?
3. Continue same dose if renal function stable -but if renal function changing, recalculate dose with current creatinine
4.
Check level in 3 days (
or more often
if impaired or rapidly changing renal function, haemodynamically unstable, elderly, or on diuretic therapy)
|
≥1 mg/L
|
1.
Is tobramycin still needed?
2.
Is it a true pre-dose (trough) (taken within one hour before dose)?
3.
Where was sample taken from? (falsely high levels can occur if taken from same line used to give tobramycin).
4.
Is dose correct for weight & renal function?
5.
Is renal function stable?
6.
Dose adjustment required -
contact Microbiology or Infectious Diseases or Pharmacy to discuss on a case-by-case basis.
|
Intravenous Vancomycin Dosing & Monitoring
Intravenous Vancomycin Dosing & Monitoring
1. Effective use of Vancomycin is complex and should normally be discussed with Microbiology or Infectious Diseases. In particular, discuss patients with renal impairment with creatinine clearance less than 30ml/minute – or those on prolonged courses. The following is provided for guidance.
2. Review empiric treatment every 24 hours.
3. The responsible clinical team must check reported Vancomycin levels and renal function regularly and adjust dosing if required. The laboratory does NOT alert teams of out of range results. Levels are available daily from 8am to 8pm.
4. Do not hold doses pending levels unless specifically requested to do so or toxicity suspected. This practice frequently results in sub-therapeutic levels.
Table 1: Vancomycin Dosing Guidelines |
||||
Use the IV Vancomycin Dosing Calculator in the GAPP App to calculate the initial dose of vancomycin. The calculator is suitable for patients with stable renal function – and will not produce reliable results in patients who are anuric or in acute renal failure. Advice should be sought from your ward pharmacist or Microbiology or Infectious Diseases. Details provided below for background information. |
||||
Step 1 |
Estimate renal function: Patient age, weight, height & creatinine required |
· Must use creatinine clearance ( not eGFR) to dose vancomycin. · Calculate the patient’s estimated creatinine clearance using Cockcroft & Gault equation. Use Vancomycin Dosing Calculator · Neither creatinine clearance nor eGFR provide a perfect marker of renal function, particularly if rapidly changing renal function. |
||
Step 2 |
Does the patient need a loading dose? |
· Initial loading dose of 25mg/kg (maximum 2g) by IV infusion recommended for critical care patients, haematology/oncology patients, complicated infections e.g. endocarditis, osteomyelitis, bloodstream infection, meningitis, or MRSA pneumonia, and if recommended by Microbiology or Infectious Diseses. · Use actual body weight to calculate the dose. · Round dose to nearest multiple of 250mg. |
||
Step 3 |
Select an initial maintenance dose based on renal function and actual body weight |
|||
Creatinine Clearance: (ml/minute) |
Dose: Round to nearest multiple of 250mg |
Frequency: |
||
Greater than 50 |
15mg per kg IV (max 2g) |
Every 12 hours |
||
20 to 50 |
15mg per kg IV (max 2g) |
Every 24 hours |
||
less than 20 |
15mg per kg IV (max 2g) |
Re-dose based on levels, generally every 3 to 7 days; discuss with Microbiology or Infectious Diseases or Pharmacy |
||
Intermittent haemodialysis: See Haemodialysis Dosing Guidelines |
Table 2: Vancomycin Administration and Monitoring Guidelines |
|
Administration |
|
Monitoring |
|
Table 3: Interpretation of Vancomycin Levels |
||||
|
||||
If target level is 10 to 15mg/L |
|
If target level is 15 to 20mg/L |
||
Level |
Advice |
Level |
Advice |
|
< 10mg/L Low |
|
< 15mg/L Low |
|
|
10 to 15 Target Range |
|
15 to 20 Target Range |
|
|
>15mg/L High |
|
>20mg/L High |
|
References
1. The Renal Drug Database www.renaldrugdatabase.com [accessed February 2024]
2. The Sanford Guide to Antimicrobial Therapy Digital Update May 2024
3. Rybak et al Vancomycin Therapeutic Guidelines: A Summary of Consensus Recommendations from IDSA/ASHP/SIDP Clin Infect Dis 2009 49;325-327.
4. Thomson et al Development and evaluation of vancomycin dosage guidelines designed to achieve new target concentrations JAC 2009;63:1050-1057.
Cockcroft and Gault Equation