Vancomycin  Single Level Analysis

Patient:
Location:

Drug:
Weight:

Current dose being given: mg
Current dosing interval: hrs Current infusion time (hrs):

Single level drawn  Trough

Trough level obtained:
mcg/ml

When was the trough drawn?: Enter number of hours since last dose:
hrs
Important note: This version was requested because the actual dosing
interval may deviate from the medical order (nurse infused dose early/late etc).
The time below should reflect the number of hours since the last dose was given.
If the trough level was drawn 12.5 hours after the last dose, enter 12.5.
Note: program will use this as the new dosing interval in order to take into
account the extended elimination time. In the
original version the
denominator is calculated by subtracting the dosing interval from the
time the trough was drawn. 

Desired peak: mcg/ml
Desired trough:
mcg/ml 

Updates

A new program was created to determine when to administer the
next dose of vancomycin after a supratherapeutic trough is
obtained. An estimated elimination rate constant is
generated from the creatinine clearance which is then used to
determine the timing of the next dose based on the desired target
trough concentration.
I also updated our current trough calculator to
also generate an estimated vancomycin kel value based on the creatinine
clearance. Use this program if the vancomcyin level is drawn early and you want to
estimate the actual trough just before the next dose to
determine if the current regimen is appropriate 
link to new program.) 
Background

AmbroseWinter's Single Trough Method Principles:
A population Vd is used to estimate the [Peak].
This calculated [Peak] and measured [Trough] are then used to calculate an
elimination rate constant (kel).
[Peak]=measured [Trough] + Dose/Vd
kel = ln ([Peak]/[Trough])/Tau
Infusion equations are then used to calculate a new Tau and Dose.
Side note: the GlobalRPh calculator uses the Vd recommended in
Bauer's text: 0.7 L/kg.
Use the advanced version if you wish to manipulate this
value.
Reference
Ambrose PJ, Winter ME. In: Winter ME. Basic clinical pharmacokinetics, 4th ed.
Philadelphia: Lippincott Williams & Wilkins; 2004:45176.
Alternate expression of kel equation:
Normally kel = (Ln C1 / C2) / (t2  t1)
C1= actual or extrapolated Peak; or post peak level
C2= actual or extrapolated trough; or random level
Drawn at least 1.5 x estimated halflife after first level.
(t2  t1) = Time difference between levels.
Equation 15.5 page 455:
cmax = [cmin + dose (s) (f)] / Vd 
Related pharmacokinetic calculators
Allows the user to estimate the actual (extrapolated) trough based on the elimination rate constant and the number of hours the level was drawn before the next scheduled dose. A
supratherapeutic level may be actually therapeutic if it was drawn just before the next dose.
This new program can be used to determine when to administer the next dose of vancomycin after a supratherapeutic trough is obtained. An estimated elimination rate
constant is generated from the creatinine clearance which is then used to determine the timing of the next dose based on the desired target trough concentration.
Use this program if the vancomcyin level is drawn early and you want to estimate the actual trough just before the next dose to determine if the current regimen is
appropriate
If you would like to enter the time since the last dose was given, use this version. This new version may be especially useful if the trough was drawn late and thenext dose was
delayed. Example: current regimen vanco 1 gram q12h. Trough wasdrawn 12.5 hours after the last dose.
The GlobalRPh vancomycin singlelevel calculator uses the Vd recommended in Bauer's text: 0.7 L/kg. Use the advanced version if you wish to manipulate this value.
