Transcript Microdialysis as a tool for assessment of tissue

Evaluation of Tissue Distribution of TR-700 in
Healthy Volunteers Using Microdialysis
Martina Sahre1,
Sreedharan Sabarinath1, PhD
Maria Grant2, MD,
Christoph Seubert3, MD, PhD,
Carisa deAnda4, PharmD
Hartmut Derendorf1, PhD
University of Florida,
College of Pharmacy, Departments of Pharmaceutics1, Therapeutics and
Pharmacology2, Anesthesiology3,
Trius Therapeutics4, San Diego, California
Overview
 Introduction
 TR-700 / TR-701
 Rationale
 Microdialysis
 Study Design
 Results
 Conclusion
TR-700
 Oxazolidinone class
 Limited water solubility
 Phosphate ester prodrug (TR-701)
 Rapid conversion to active drug
TR-700
 Oxazolidinone class
 Indication complicated skin and skin structure infections
(cSSSI)
 In vitro activity against:
 S. aureus (MS and MR),
 Linezolid-resistant MRSA carrying binding-site mutations, cfr
gene
 S. pneumoniae (PS, PR), S. pyogenes, S. agalactiae, Enterococci
(inc.. VRE)
Rennie et al. (2003), Im et al. (2007), Jones et al. (2009), Shaw et al. (2007), Schaadt et al. (2009)
Rationale
 Plasma concentrations linked to PK/PD indices
 Free drug in tissue more relevant
 Drug molecules need to reach tissue
Mean Ceftobiprole Concentrations After
Single 500 mg i.v. Dose
C(tissue) < fc(plasma)
Total Plasma,  Muscle Tissue,
 Adipose Tissue, --- Free Plasma
Barbour et al. (2009), Deghanyar et al. (2005)
Mean Linezolid Concentrations After
Single 600 mg i.v. Dose
C(tissue) > fc(plasma)
Rationale
 Biopsy, skin blisters, imaging techniques
 AUC of Moxifloxacin after 400 mg p.o single dose:
AUC
[µg*h/mL]
Plasma
Muscle
Tissue
Subcutaneous
Tissue
Saliva
Capillary
Blood
Blister
19.8
8.5
8.0
17.6
18.7
12.3
 Measure unbound PK parameter in tissue using
microdialysis
Mueller et al. (1999)
Microdialysis Principle
 Diffusion through a
semipermeable membrane
 “Mimics” blood vessel
 Sampling tool
 Assess free drug directly
Courtesy of CMA
Recovery
 Probe is continuously perfused → no equilibrium
 cdialysate < cmedium
 Recovery defined as ratio cdialysate/cmedium
 Dialysate: liquid recovered from probe
 Medium: tissue or solution containing compound of interest
 Factors influencing recovery:
 Temperature, Membrane length, Flow-rate, Molecular size,
Membrane properties, Tissue properties
 Probe calibration → recovery factor
Retrodialysis
 Perfusate contains known concentration of compound
 Dialysate concentration measured
 Calculated recovery used to
adjust drug concentrations from
experiment
Recovery[% ]  100 
cdialysate
c perfusate
*100
Courtesy of CMA
Study Design
 TR-700 measured in plasma, s. c. adipose and muscle tissue
 15 healthy volunteers
 Pilot (n = 3) and Main Study (n = 12)
 Two microdialysis probes implanted
 Retrodialysis to calibrate probe
 Washout period
 Main Study
 Single dose of study drug, 600 mg p.o.
 Dialysate samples every 20 minutes for 12 h,
blood samples for 24 h after dosing
 Protein binding samples 0, 2, 12h post dose
CMA 60 probe, Courtesy of CMA, Sweden)
Pilot Study Results
 Recovery > 90%
 Washout period 4 h
Main Study: Results
 Protein Binding 87 % (1.3%)
TR-700
TR-700
Levels
Levels
in Plasma
in Plasma
(Total(Unbound),
and Unbound),
Adipose
Adipose
and Muscle
and Muscle
Tissues
Tissues
7000
Adipose Tissue
Muscle Tissue
fPlasma
Total Plasma
fPlasma
Concentration
Concentration [ng/mL]
[ng/mL]
800
6000
5000
600
4000
400
3000
2000
200
1000
0
0
0
4
8
12
Time [h]
16
20
24
Mean PK Parameters (SD)
Parameter
Unit
Plasma
fPlasma
Cmax
(µg/mL)
5.37 (1.51)
0.70 (0.27)
Tmax§
(hr)
2 (1-4)
2 (1-4)
AUC0-12
(µg*h/mL)
38.8 (7.55)
4.96 (1.09)
AUC0-24
(µg*h/mL)
57.1 (14.7)
7.28 (1.91)
AUC∞
(µg*h/mL)
70.0 (24.8)
8.89 (3.06)
t½§
(hr)
8.13 (5.94-12.8) 8.13 (5.94-12.8)
CL/F
(L/hr)
9.46 (2.91)
*
Vz/F
(L)
113 (19.3)
*
fAUC0-12, tissue/
fAUC0-12, plasma
Protein Binding
%
87.2 (1.3)
*
* Not applicable; § Median (Range); λz: terminal elimination rate constant
Adipose Tissue
Muscle Tissue
0.66 (0.16)
3.33 (2.33-10.3)
5.27 (1.28)
16.6 (15.8)
9.22 (5.98-85.9)
*
*
0.74 (0.15)
3.67 (1.67-7)
5.95 (1.11)
14.6 (10.5)
9.59 (6.15-48.2)
*
*
1.08 (0.22)
1.22 (0.18)
*
*
Conclusion
 TR-700 conc. in observed tissues similar to unbound plasma
concentrations
 No significant difference between AUC0-12 for unbound
plasma, adipose and muscle tissues
 Drug and microdialysis well tolerated
Acknowledgements
 Prof. Hartmut Derendorf
 Maria Grant, MD and Christoph Seubert, MD, PhD
 Sreedharan Sabarinath, PhD
 General Clinical Research Center at the University of Florida
 Philippe Prokocimer, MD
 Trius Therapeutics, Inc.
Individual Adipose Concentrations
1000
1
2
3
4
5
6
7
8
9
10
11
12
900
Concentrations [ng/mL]
800
700
600
500
400
300
200
100
0
0
60
120
180
240
300
360
420
Time [min]
480
540
600
660
720
780
Individual Muscle Concentrations
1000
900
Concentration [ng/mL]
800
700
600
500
400
300
200
100
0
0
60
120
180
240
300
360
420
Time [min]
480
540
600
660
720
780