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Pharmacodynamic Indices. Johan W Mouton. Canisius-Wilhelmina Hospital Nijmegen, The Netherlands. PEAK / MIC AUC / MIC TIME > MIC. PEAK. AUC. MIC. TIME > MIC. PK/PD. Neutropenic mouse thigh model Various doses and dosing regimens (q1 to q24) Outcome parameter: cfu counts after 24 h - PowerPoint PPT Presentation
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Canisius-Wilhelmina HospitalNijmegen, The Netherlands
Johan W Mouton
Pharmacodynamic Indices
MIC
PEAK
PEAK / MICAUC / MICTIME > MIC
AUC
TIME > MIC
PK/PD
• Neutropenic mouse thigh model
• Various doses and dosing regimens (q1 to q24)
• Outcome parameter: cfu counts after 24 h
• Plot PD index (AUC, Peak T>MIC) to effect
K. pneumoniae, imipenem
For K.pneumoniae, there is no clear relation
between total daily dose of imipenem and
efficacy in an in vivo model of infection
K. pneumoniae, imipenem
For beta-lactams, there is a direct
relation between
Time > MIC and efficacy
Scaglione et al, ICAAC 1999
Pharmacodynamic Indicespredictive for efficacy
T>MIC AUC (Peak)/MIC
Penicillins Aminoglycosides
Cephalosporins Fluoroquinolones
Carbapenems Metronidazole
Monobactams Daptomycin
Tribactams Ketolides
Clindamycin Macrolides
Oxazolidinones Azithromycin
Clindamycin Streptogramins
Glycopeptides
Glycylcyclines Tetracyclines
Kill curves of ceftazidime, P. aeruginosa
tobramycin
-2 -1 0 1 2 3-2
3
8
13
18
10log (conc tobramycin) mg/lki
llrat
e h
-1
meropenem
-3 -2 -1 0 1 2-2
-1
0
1
2
3
4
5
10log (conc meropenem) mg/l
killr
ate
h-1
Mouton & Vinks, 2003
Kill curves of tobramycin, P. aeruginosa
•Antibiotics showing increasing effect (killing) over a wide range of concentrations are called ‘concentration dependent’. In vivo effects are usually AUC and/or Peak related.
•Those with a limited range of increasing effect are called (wrongly) ‘concentration-independent’. In vivo effects are usually Time >MIC related.
Pharmacodynamic index
Pharmacokinetic parameter MIC
The MIC
The MIC is a result of :
•kill over time (kill rate) by the antibiotic •growth over time (growth rate) •for a certain number of micro-organisms (the inoculum)
MIC
AT STATIC CONCENTRATIONS
•Growth and/or kill rate dependent :–strain, species–medium composition, brand
–MH, supplements, ISO–number of bacteria–inoculum
–5.105 (NCCLS) vs 105 (BSAC)–temperature (35o vs 37o)–growth phase–CO2
–etc.
0.0 0.5 1.0 1.5 2.0-6
-5
-4
-3
-2
-1
0
microdilution
e-test
10log MH dilution
2lo
g n
orm
aliz
ed M
IC
r²
2log mic
0.9457
2log etest
0.9507
Mouton, icaac 2000
The MIC of the control strain should be within one two-fold dilution of the expected MIC
PHARMACOKINETICparameters
Definition :The Area under the Concentration-time curve over 24 hours.Note: ….. It should be stated how the AUC is determined : based on (log) linear trapezoideal rule, based on clearance, or based on microconstants.
Dimensions : concentration x time e.g. mg.h/L or g.h/mL
Mouton et al, Int J Antimicrob Agents april 2002
AUC 0-24 = 3033 AUC inf = 5100AUC 0-24 sd = 1361AUC inf sd =1700
0 10 20 30 400
100
200
time
con
cen
trat
ion
Mg.h/L
WHICH AUC?
•AUC 0-24h or AUC
•Steady State?
• (log) trapezodeal rule?
•Derived ? (A/ +B/ or other)
Peak/MICDefinition : the peak level divided by the MIC.
Dimensions : no dimensions.
Mouton et al, Int J Antimicrob Agents april 2002
WHICH PEAKLEVEL?
•After the 1st, 2nd or later dose?
•If more than one compartment, the peak level in compartment 1, 2 or even 3?
simulation of 1.25 mg/kg q1h
0 1 2 3 4 5 6 7 80.0
0.5
1.0
1.5
2.0simulated conc.measured conc.
time (h)
con
cen
trat
ion
mg
/Lsimulation 10 mg/kg +
1.25 mg/kg q1h
0 4 8 12 16 20 240
2
4
6
8
10
simulated conc.
time (h)
con
cen
trat
ion
mg
/L
simulation 10 mg/kg + 1.25 mg/kg q1h
0 4 8 12 16 20 240
2
4
6
8
10
simulated conc.
time (h)
con
cen
trat
ion
mg
/L
fig 2a
fig 2b
fig 2c
Scaglione et al, icaac 1999
0.1 1 10 1000.6
0.7
0.8
0.9
1.0
fu levfu cip
concentration mg/l
frac
tio
n u
nb
ou
nd
fig 1
Scaglione et al, unpubl.
Time > MICDefinition : the % of time above the MIC over a period of 24 hours.Note : if the period is other than 24 h, this should be stated explicitly.
Dimensions : %.
Mouton et al, Int J Antimicrob Agents april 2002
Concentration-time profile of beta-lactamVd = 20 L, Ka = 1.2 h-1, Ke = 0.3 h-1
0.20
1.20
2.20
3.20
4.20
5.20
6.20
7.20
8.20
9.20
10.20
11.20
12.20
13.20
14.20
15.20
16.20
17.20
18.20
19.20
0.00
1.25
2.50
3.75
5.00
6.25
7.50
8.75
10.0
0
11.2
5
12.5
0
13.7
5
15.0
0
16.2
5
17.5
0
18.7
5
20.0
0
21.2
5
22.5
0
23.7
5
0.95-1.00
0.90-0.95
0.85-0.90
0.80-0.85
0.75-0.80
0.70-0.75
0.65-0.70
0.60-0.65
0.55-0.60
0.50-0.55
0.45-0.50
0.40-0.45
0.35-0.40
0.30-0.35
0.25-0.30
0.20-0.25
0.15-0.20
0.10-0.15
0.05-0.10
0.00-0.05
Conc
Time
Prob
Monte Carlo Simulation of beta-lactamVd = 20 L, Ka = 1.2 h-1, Ke = 0.3 h-1, VC=20%
4h
10h
Mouton, Int J Antimicrob Agents april 2002
Mouton et al, Clin Pharmacokin 2000
Mouton & Punt, JAC 2001
Amoxicillin/clavulanic acid
For all indices :
how are they determinedhow are they calculated
what is the error?