• Serious MRSA infections on advice of consultant microbiologist

• As vancomycin has a narrow therapeutic index, accurate dosing is imperative to prevent toxicity
• If CrCl <10 mL/min or on haemodialysis/peritoneal dialysis, contact renal SpR/consultant for advice on dose

Loading and maintenance doses

STEP 1 - WEIGH PATIENT

• If unfit to be weighed, estimate weight

STEP 2 - LOADING DOSE

• Use ACTUAL or estimated body weight - not ideal body weight (IBW)
• Use Table 1 to select loading dose and volume and duration of infusion
• Loading dose is independent of patient's renal function
• Prescribe on once only antimicrobial section of prescription chart

Table 1

Actual/estimated body weight	Dose	Volume of sodium chloride 0.9% or glucose 5%	Duration of infusion
<40 kg	750 mg	250 mL	1.5 hr
40-59 kg	1 g	250 mL	2 hr
60-89 kg	1.5 g	500 mL	3 hr
≥90 kg	2 g	500 mL	4 hr

STEP 3 - MAINTENANCE DOSING

• Calculate renal function using equations below. DO NOT use eGFR
• If patient's creatinine <60 µmol/L use 60 µmol/L as a minimum value to avoid falsely producing high creatinine clearance
  • female:

    CrCl =	1.04 x (140 - age) x weight* (kg)
    	serum creatinine (µmol/L)

  • male:

    CrCl =	1.23 x (140 - age) x weight* (kg)
    	serum creatinine (µmol/L)

  *weight - use IDEAL body weight (IBW) unless patient appears underweight - See Ideal body weight guideline

  If patient appears underweight and is fit to be weighed, use ACTUAL body weight

  If patient appears underweight AND is unfit to be weighed, ESTIMATE body weight

• Based on calculated CrCl, select maintenance dose from Table 2
• Maintenance dose should NOT be higher than loading dose

Table 2 Maintenance doses

CrCl (mL/min)	Dose	Volume of sodium chloride 0.9% or glucose 5%	Duration of infusion	Dose interval (time since loading dose and time between maintenance doses)	Timing of samples Placed in text under vancomycin levels
<10	See advice above
10-19	500 mg	100 mL	1 hr	48 hr	Trough concentration immediately before both 1st and 2nd maintenance doses
20-29	500 mg	100 mL	1 hr	24 hr
30-39	750 mg	250 mL	1.5 hr	24 hr
40-54	500 mg	100 mL	1 hr	12 hr	Trough concentration immediately before 3rd or 4th maintenance dose - whichever falls before morning dose
55-74	750 mg	250 mL	1.5 hr	12 hr
75-89	1 g	250 mL	2 hr	12 hr
90-110	1.25 g	250 mL	2.5 hr	12 hr
>110	1.5 g	500 mL	3 hr	12 hr
n/a	1 g	250 mL	2 hr	8 hr
n/a	1.25 g	250 mL	2.5 hr	8 hr

• Monitor creatinine daily

Vancomycin levels

• Therapeutic drug monitoring is recommended to ensure adequate serum concentration
• Results are meaningless unless dose and sample time are recorded accurately
• Do not wait for result before giving dose due immediately after taking sample, unless patient has severe renal impairment (CrCl <10 mL/min) or poor urine output (<0.5 mL/kg/hr)

Document on prescription chart

• Time each infusion started
• Time sample taken

Record on request form

• Dose of vancomycin
• Date and start time of infusion last administered to patient
• Dose regimen

Timing of samples

• If CrCl < 10 mL/min or on haemodialysis/peritoneal dialysis, contact renal SpR/consultant for advice on timing
• If 10 < CrCl < 40 mL/min, take trough concentration immediately before both 1^st and 2^nd maintenance doses
• If CrCl ≥ 40 mL/min, take trough concentration immediately before 3^rd or 4^th maintenance dose, whichever falls before morning dose

• Usual target trough concentration: 10-15 mg/L
• The microbiology/ID consultant may advise a target trough concentration up to 20 mg/L in some serious infections
  • MRSA pneumonia
  • osteomyelitis
  • endocarditis
  • bacteraemia
  • severe cellulitis
• Always check dosage history and sampling time are appropriate before interpreting result
• If necessary, request assistance in interpreting result from pharmacy

Suggested dose change

The possible maintenance dose bands are:

-1. As suggested dose very low, seek advice from microbiology
0. As suggested dose very low, seek advice from microbiology
1. Dose=500mg; frequency 48hrs
2. Dose=500mg; frequency 24hrs
3. Dose=750mg; frequency 24hrs
4. Dose=500mg; frequency 12hrs
5. Dose=750mg; frequency 12hrs
6. Dose=1g; frequency 12hrs
7. Dose=1.25g; frequency 12hrs
8. Dose=1.5g; frequency 12hrs
9. Dose=1g; frequency 8hrs
10. Dose=1.25g; frequency 8hrs
11. As suggested dose very high, seek advice from microbiology
12. As suggested dose very high, seek advice from microbiology

The microbiologists and pharmacists advise adjusting doses by obeying the rules in the table below.
The table is followed in the "Dose Adjuster"

Interpretation of levels and dose adjustment Use pre-dose trough level (below) to adjust dose / frequency NOT CrCl once therapy initiated
Pre-dose trough level (mg/L)	If aiming for 10-15 mg/L	If aiming for 15-20mg/L (for MRSA pneumonia, osteomyelitis, endocarditis, bacteraemia & severe cellulitis +/- systemic symptoms only)
< 5	Move up 2 dosing bands	Move up by 3 dosing bands
5.1 - 10	Move up one dosing band	Move up by 2 dosing bands
10.1 - 15	Continue at current dose	Move up by one dosing band
15.1 - 20	Move down one dosing band without omitting any doses	Continue at current dose
20.1 - 25	Decrease by two dosing bands without omitting any doses	Move down one dosing band without omitting any doses
>20.1 <30	Omit next dose & decrease by two dosing bands
> 30	Seek advice from Microbiology

Further monitoring

• If renal function impaired but stable, check trough concentration on alternate days
• If renal function is changing rapidly (deteriorating or improving), check trough concentration daily to prevent over- or under-treatment
• If dose has to be changed, take further samples for trough concentration before appropriate dose. See Timing of samples

• If required, contact ward pharmacist, antimicrobial pharmacist or Medicines information
• Out-of-hours contact on-call pharmacist or microbiologist