ANTIBIOTIC DOSE AND DOSE INTERVALS IN RRT and ECMO

ANTIBIOTIC DOSE AND DOSE INTERVALS IN RRT and ECMO

Department of

Intensive Care Medicine

Royal Brisbane Hospital

University of Queensland

Professor Jeffrey Lipman

NO CONFLICT

OF INTERESTS

Important concept

Recommended dosages are obtained from healthy volunteers and possibly (ward)

“sick” patients

Clinical pharmacology:

drug development

Antibiotic regimens are derived from non-critically ill volunteers. Their haemodynamic system is normal, as is their liver and kidney blood flow. They have not leaky capillaries nor have they drips and pipes in every orifice.

Blot S et al. Diagnostic Microbiology and Infectious Disease 2014;79:77–84

The kidney and antibiotics

Cmax Peak Concentration

Cmin Trough Concentration

t1/2 Half-life

V (or VD) Volume of distribution

AUC Area under curve

Cl Clearance

Protein binding

Antibiotic related IMPORTANT

pharmacokinetic parameters

Capillary lead and fluid administration

Marik PE Anaesthesia and Intensive Care 1993;21:172-3.

….we have found that higher-than-recommended loading and daily doses of vancomycin seem to be necessary to rapidly achieve therapeutic serum concentrations.

35mg/kg loading 35mg/kg/day

Antibiotics that stay in extravascular and

extracellular space ie that don’t penetrate

“solid” organs, (hydrophilic tendencies)

namely AMINOGLYCOSIDES

GLYCOPEPTIDES

β-LACTAMS (to a lesser extent)

COLISTIN

VOLUME OF DISTRIBUTION

ALTERATIONS IN ICU

LOADING DOSE vs

CLEARANCES

Fundamental concept Loading dose is INDEPENDENT of

clearances

EVEN IN RENAL FAILURE (without

clearance) YOU MUST GIVE

LOADING DOSE

LOW EXPOSURE TO ANTIBIOTICS ENABLES

DEVELOPMENT OF RESISTANCE

Critical Care Medicine August 2008;36:2433-40

Sepsis changes PK

Extracorporeal circuits

Altered CL and Increased Vd cf AKI

? Plasma concentrations

Kidney Filter

Ultrafiltrate Dialysate

FLOW

FLOW

Semi-permeable Membrane

(C)RRT

(Continuous) Renal

Replacement Therapy

Ultrafiltrate

FLOW

Semi-permeable

Membrane

CRRT Effects on Electrolytes and Water

..…and Drugs.

+/- Dialysate

Ur Cr

K Ca PO4

Ur Cr Cr

Cr Cr

Ur Ur

K Ca PO4

H2O H2O

FLOW

Then it’s easy!

If you know

1. Membrane Pore Size

2. Drug Size

3. Sieving Coefficient

DRUG CLEARANCE

Then it’s easy!

If you know


2. Drug Size


DRUG CLEARANCE

CRRT Continuous Renal Replacement Therapy

Access (Pre- Filter)

From Patient

Return (Post Filter)

To Patient

Kidney Filter


FLOW

FLOW



From Patient


To Patient

Kidney Filter


FLOW

FLOW


CVVHD Continuous Veno-Venous HeamoDialysis

NO Replacement Fluid.

Effluent

FLOW

Semi-permeable

Membrane

CVVHD Removal of urea, toxins, electrolytes

& DRUGS (small molecules)

Dialysate

Ur Cr

K Ca PO4

Ur Cr Cr

Cr Cr

Ur Ur

K Ca PO4

FLOW

CVVHD

Sd = [Antibiotic] dialysate

[Antibiotic] plasma

CVVHD

ClCVVHD ≈ Qd x Sd

Ultrafiltrate

FLOW

Semi-permeable

Membrane

Ur Cr

K Ca PO4

Ur Cr Cr

Cr Cr

Ur Ur

K Ca PO4

H2O H2O

CVVH Removal of H2O, urea, toxins, electrolytes

& DRUGS (small + middle molecules)

H2O

H2O H2O

H2O

H2O

H2O

H2O


From Patient


To Patient

Kidney Filter

Ultrafiltrate

FLOW

FLOW


CVVH Continuous Veno-Venous Heamofiltration

Replacement Fluid can be either

Pre- Filter or Post Filter.

NO Dialysate

[Antibiotic] ultrafiltrate

[Antibiotic] plasma Sc =

CVVH

Cl CVVH(pre) = Qf x Sc x CF

where CF = Qb

Qb + Q pre

CVVH


From Patient


To Patient Kidney Filter

Ultrafiltrate

FLOW

FLOW


CVVHDF Continuous Veno-Venous HeamoDiaFiltration

Dialysate

Replacement Fluid can be either

Pre- Filter or Post Filter.

SLEDD as an alternative

And then there is SLEDD

Slow Low Efficiency Daily Dialysis, Extended Daily Dialysis

A “Hybrid” of CRRT + IHD

Minimal antibiotic clearance data published

Roberts, Lipman. (Editorial) Crit Care Med 2011;39:602-3

Crit Care Med 2011;39:560–70

Nine original research articles plus a few case reports

Therapeutic Options of

RRT Differ

CVVH

CVVHD

CVVHDF

SCUF

SLEDD

Tables and equations

Then it’s easy!

If you know


2. Drug Size


Then it’s easy!

If you know


2. Drug Size


Convection

Diffusion

Protein binding

Volume of distribution

Membrane characteristics

HOW DO WE DOSE

AT MY HOSPITAL?

Roberts JA et al. Int J Antimicrob Agents 2010;36:332-0

Roberts JA, Hope WW, Lipman J. Int J Antimicrob Agents 2010;35:419-20

BEST WE HAVE

Choi et al Crit Care Med 2009;37:2268-82

CRRT and MEROPENEM

Jamal et al Crit Care Med 2014:42:1640-50

CRRT and PIPTAZO


CRRT and VANC


ONE WAY


Advantages

Individualized

CRRT

MIC

Takes PK/PD relationships into account

Choi G et al. Crit Care Med 2009; 37: 2268-82

Choi G et al. Blood Purif 2010; 30: 195-212

Alternatively

Choose a PK article that most closely

resembles the form of CRRT you use

Use their clearances – see if it seems

a reasonable estimate of your

clearances

Dose accordingly

RECENTLY ACCEPTED REVIEW

Jamal JA, Mueller BA, Choi GYS, Lipman J, Roberts JA

How can we ensure effective antibiotic dosing in critically ill patients receiving different types of renal replacement therapy?

Diagnostic Microbiology and Infectious Disease

RECENTLY ACCEPTED REVIEW

Jamal JA, Mueller BA, Choi GYS, Lipman J, Roberts JA

How can we ensure effective antibiotic dosing in critically ill patients receiving different types of renal replacement therapy?

Diagnostic Microbiology and Infectious Disease

TABLE 1: Pharmacokinetic parameters of different class of antibiotics in critically ill patients receiving variable types of renal replacement therapy modalities

IMPORTANT BEDSIDE

PRACTICAL POINT…..

You may prescribe Continuous RRT….

but is it continuous? How often do you

come on morning ward round to here

the “kidney” was off for xxx hours? How

often do you do rounds to here “Oh we

are changing the filter”……

Do you factor in for the “down time”?

IMPORTANT BEDSIDE

PRACTICAL POINT…..

What do you do when you want to

cease RRT. We say “leave the filter off

for awhile to see if pt passes urine…”

And often forget to change dose of drugs…..

Do you factor in for the “down time”?

Conclusions:

This matched cohort study confirms an increase in Vd and a decrease in CL

for meropenem in adult patients receiving ECMO. In patients receiving

meropenem on ECMO, standard dosing does not always result in optimal

drug concentrations because of the significant PK changes in the setting of

critical illness, ECMO and RRT. Therapeutic drug monitoring where

possible is recommended until robust dosing guidelines become available.

CRITICAL CARE

Therapeutic drug monitoring

DEFINITION

Therapeutic Drug Monitoring (TDM)

refers to analysis and subsequent

interpretation of drug concentrations in biological fluids

PLACE

TDM should be used to

maximise efficacy

minimize toxicity

To personalise dosing for high probability of

therapeutic success, prevent development of

resistance, provide low probability of toxicity

BETA-LACTAMS

Safe drugs

Large therapeutic range

TDM should be used to

maximise efficacy minimize toxicity

J Chromatogr B 2010;878:2039-2043

CONCLUSION

For various reasons therapeutic drug

monitoring (TDM) of most antibiotics is

difficult if not impossible. We have set up

a TDM service for all our beta-lactam use

and have (not surprisingly ) shown that in

more than half of our ICU patients we are

dose adjusting once receiving back a drug

level!

THE END !

[email protected]

www.som.uq.edu.au/btccrc

ONE WAY


Time above threshold

concentration Cmax:MIC & AUC24:MIC

Cmax:MIC ratio

Loading dose=Desired concentration x Vd

Calculate CRRT clearance based on mode of CRRT, formulae & published values

Pharmacokinetic

target?

Calculate elimination rate

= concentration x Cltot

Total clearance (Cltot) =calculated CRRT clearance+non-CRRT clearance

Maintenance infusion rate=

elimination rate

Calculate half-life

= 0.693 x Vd / Cltot

Calculate time to reach

target trough concentration

Repeat loading dose at

calculated time

Calculate target mean

concentration

= target AUC24/24

Calculate dosing interval

= Dose/(Cp x Cltot )


calculated dosing interval



Cmax:MIC ratio



Pharmacokinetic

target?





elimination rate

Calculate half-life





calculated time


concentration

= target AUC24/24





Loading dose=Desired concentration x Vd (28 l)

Desired concentration = 5 x MIC = 20 mg/l

Loading dose = 20 x 28 500 mg



Cmax:MIC ratio



Pharmacokinetic

target?





elimination rate

Calculate half-life





calculated time


concentration

= target AUC24/24





Calculate CRRT clearance based on mode of CRRT

& published Sc or Sd values

ClCVVH (post) = Qf x Sc

= 2450 x 0.95 = 2327 ml/h = 39 ml/min



Cmax:MIC ratio



Pharmacokinetic

target?





elimination rate

Calculate half-life





calculated time


concentration

= target AUC24/24






= 39 + 60 100 ml/min = 0.1 l/min



Cmax:MIC ratio



Pharmacokinetic

target?





elimination rate

Calculate half-life





calculated time


concentration

= target AUC24/24







= 20 x 0.1 = 2 mg/min



Cmax:MIC ratio



Pharmacokinetic

target?





elimination rate

Calculate half-life





calculated time


concentration

= target AUC24/24





Maintenance infusion rate

= elimination rate

= 2 mg/min

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ANTIBIOTIC DOSE AND DOSE INTERVALS IN RRT and ECMO