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Vancomycin - Single Level Analysis
Current dose being given
Current dosing interval
Current infusion time (hrs)
Single level drawn - Trough
Trough level obtained
When was the trough drawn?
Enter number of hours since last dose
: This version was requested because the actual dosing interval may deviate from the medical order (nurse
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
the denominator is calculated by subtracting the dosing interval from the time the trough was drawn.
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
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
Ambrose-Winter’s Single Trough Method
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.
: the GlobalRPh calculator uses the Vd recommended in Bauer's text: 0.7 L/kg.
if you wish to manipulate this value.
Ambrose PJ, Winter ME. In: Winter ME. Basic clinical pharmacokinetics, 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2004:451-76.
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 half-life after first level.
(t2 - t1) = Time difference between levels.
Equation 15.5 page 455:
cmax = [cmin + dose (s) (f)] / Vd
All calculations must be confirmed before use. The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.
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