V2, A2, C2
V1, A1, C1
V4, A4, C4
V3, A3, C3
The impact of the BBB and BCSFB transporters in
translational drug distribution models
Elizabeth CM de Lange
Translational Pharmacology, LACDR, Leiden University, The Netherlands
[email protected]
1
Treatment of brain diseases
Need for more
knowledge and understanding
of processes that determine
CNS drug effects ….
and their interdependencies
2
Processes that govern CNS drug response
Homeostatic feedback
-brain barrier
Plasma
exposure
Blood
Drug
Dosing
Target
tissue
exposure







Homeostatic
feedback
TransTarget
duction
exposure
E
Transduction
RESPONSE
Drug Dosing
Plasma concentration-time profile
BBB transport
Target tissue cioncentration-time profile
Target binding kinetics
Cellular signal transduction & homeotstatic feedback
Body response & homeostatic feedback
3
Blood-brain barrier (BBB)
Four basic modes of BBB transport
Simple diffusion, driven by the
concentration-gradient, from
high to low concentrations.
Facilitated diffusion, by a helper
molecule, also from high to low
concentrations.
Fluid phase transport by vesicles,
formed out of the membrane.
This transport requires energy
and occurs into the direction of
the brain.
Active transport through a
transporter protein for which the
molecule should have a specific
binding site. Active transport
requires energy and conducts
movement against the
concentration gradient.
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Blood-brain barrier (BBB)
Relationship between brainECF and plasma PK
depends on BBB transport
Linear transport into and out
of the brain
Passive transport, unequal CLin
and CLout
Clin = Clout
Varying from 1.0 to 0.01
CLout = 0.5
Varying CLin from 0.5 to 0.01
MODEL
Used for simulations
Hammarlund-Udenaes, Paalzow, and de Lange. Pharm Res, 14(2) 1997
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Brain microdialysis
Monitoring free drug
concentrations in the brain
De Lange et al. Intracerebral microdialysis in PK studies on drug transport across the BBB. Brain Res Rev. 1997
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In vivo monitoring
Serial blood
sampling
Drug
Co-drugs
Response measure (e.g. EEG)
Blood concentration
Microdialysate concentration
-30
0
Time (min)
360
De Lange. The mastermind approach to CNS drug therapy. FBCNS. 2013
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Prediction of human brain PK?
Consider local differences in brain pharmacokinetics
..... and consider target site locations
De Lange. Utility of CSF in translational neuroscience. JPKPD. 2013
8
Prediction of human brain PK?
De Lange. Utility of CSF in translational neuroscience. JPKPD. 2013
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Prediction of human brain PK?
Acetaminophen – passive diffusion & flow
ST LV
CM
15 mg/kg/10min
Westerhout et al. PBPK Modeling to Investigate Regional Brain Distribution Kinetics in Rats. AAPSJ. 2012
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Prediction of human brain PK ?
ST LV
Quinidine- passive diffusion and active transport
CM
Striatum ST, Lateral ventricle LV, Cisterna magna CM
Plasma,u and brain,u (20 mg/kg ± TQR)
Quinidine concentration (ng/ml)
Quinidine concentration (ng/ml)
Plasma,u and brain,u (10 mg/kg ± TQR)
10000
1000
100
10
1
0
60
120
180
Time (min)
240
300
360
10000
1000
100
10
1
0
60
120
180
240
300
360
Time (min)
Westerhout et al. The impact of P-gp functionality on non-SS relationships between CSF and brainECF. JPKPD. 2013
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Prediction of human brain PK ?
CM
Quinidine concentration (ng/ml)
Quinidine
ST LV
1
Westerhout et al. The impact of P-gp functionality on non-SS relationships between CSF and brainECF. JPKPD. 2013
12
Prediction of human brain PK?
ST LV
CM
Methotrexate - passive diffusion & flow + active transport
Striatum ST, Lateral ventricle LV, Cisterna magna CM
Brain ECF (40-)
Brain ECF (40+)
CSF LV (40-)
CSF LV (40+)
CSF CM (40-)
CSF CM (40+)
40 mg/kg - probenecid
40 mg/kg + probenecid
Concentration (ng/ml)
1000000
100000
10000
1000
100
10
Methotrexate, 80 mg/kg ± probenecid
Brain ECF (80-)
Brain ECF (80+)
CSF LV (80-)
CSF LV (80+)
CSF CM (80-)
CSF CM (80+)
80 mg/kg - probenecid
80 mg/kg + probenecid
1000000
Concentration (ng/ml)
Methotrexate, 40 mg/kg ± probenecid
100000
10000
1000
100
10
1
1
0,1
0,1
0
60
120
180
Time (min)
240
300
0
60
120
180
240
300
Time (min)
Westerhout et al. Prediction of methotrexate CNS distribution in different species. EJPS 2014
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Prediction of human brain PK?
Methotrexate - passive diffusion & flow + active transport
ST LV
CM
Striatum ST, Lateral ventricle LV, Cisterna magna CM
Visual predictive check
Westerhout et al. Prediction of methotrexate CNS distribution in different species. EJPS 2014
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Prediction of human brain PK?
Species physiological parameter values
Replacement of rat by human values for brain physiological parameters:
Parameter
Rat value
Human value
CSF volume
250 µl
150 ml
CSF production
2.2 µl/min
0.35 ml/min
CSF turnover
11 times/day
4 times/day
Brain weight
1.8 g
1400 g
BrainECF volume
290 µl
240 ml
BrainECF production (bulk flow)
0.2-0.5 µl/min
0.15-0.20 ml/min
Cerebral blood flow
1.1 ml/min
700 ml/min
De Lange. Utility of CSF in translational neuroscience. JPKPD. 2013
(including references on the parameters displayed in the table above)
De Lange. Utility of CSF in translational neuroscience. JPKPD. 2013
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Prediction of human brain PK?
Acetaminophen
Prediction of human data
Predicted Human Acetaminophen
Concentration (ng/ml)
100000
Plasma observed
CSF (SAS) observed
Plasma predicted
SAS (CSF) predicted
Brain ECF predicted
LV
CM
10000
1000
100
0
120
240
360
480
600
720
Time (min)
Observed (Bannwarth et al. Br J Clin Pharmacol. 1992) and
predicted human acetaminophen concentrations in plasma
(, ….) and CSF (о, - -- -)
Westerhout et al. PBPK Modeling to Investigate Regional Brain Distribution Kinetics in Rats. AAPSJ. 2012
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Prediction of human brain PK?
Acetaminophen
Prediction of human data
Predicted Human Acetaminophen
Concentration (ng/ml)
100000
Plasma observed
CSF (SAS) observed
Plasma predicted
SAS (CSF) predicted
Brain ECF predicted
LV
CM
10000
1000
100
0
120
240
360
480
600
720
Time (min)
Observed (Bannwarth et al. Br J Clin Pharmacol. 1992) and
predicted human acetaminophen concentrations in plasma
(, ….) and CSF (о, - -- -)
Westerhout et al. PBPK Modeling to Investigate Regional Brain Distribution Kinetics in Rats. AAPSJ. 2012
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Prediction of human brain PK?
Acetaminophen
Prediction of human data
Predicted Human Acetaminophen
Concentration (ng/ml)
100000
Plasma observed
CSF (SAS) observed
Plasma predicted
SAS (CSF) predicted
Brain ECF predicted
LV
CM
10000
1000
100
0
120
240
360
480
600
720
Time (min)
Observed (Bannwarth et al. Br J Clin Pharmacol. 1992) and
predicted human acetaminophen concentrations in plasma
(, ….) and CSF (о, - -- -)
Westerhout et al. PBPK Modeling to Investigate Regional Brain Distribution Kinetics in Rats. AAPSJ. 2012
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Methotrexate conc (ug/ml)
Westerhout et al. Prediction of methotrexate CNS distribution in different species. EJPS 2014
Discussion & Conclusions
• The BBBs may have an important impact on the relationship between
plasma and brain PK
• Preclinical microdialysis brain data are extremely useful in unraveling
factors in drug brain distribution
• The BBBs (especially transporters) may have also an important impact on
the relationships between PK in different brain compartments
• An advanced generic brain distribution model has been developed, using
preclinical data on brain distribution of compounds with different physicochemical and transporter interaction properties
• This model can be “humanized” to reasonably predict human brain
distribution of drugs in healthy conditions
• Deviations from the healthy prediction may inform us on what changes in
human disease conditions
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Dirk-Jan van den Berg
Els van Beelen
Francesco Bellanti
Willem vd Brink
Sinziana Cristea
Meindert Danhof
Nathalie Doorenweerd
Tony Figaji
Janna Geuer
Piet Hein van der Graaf
Margareta Hammarlund-Udenaes
Robin Hartman
Sandra den Hoedt
Laura Kervezee
Naomi Ketharanathan
Maaike Labots
Victor Mangas
Ron Mathôt
Nick van Oijen
Ursula Rohlwink
Shinji Shimizu
Jasper Stevens
Stina Syvanen
Dick Tibboel
Yumi Yamamoto
Joost Westerhout
Enno Wildschut
Wilbert de Witte
Eric Wong
Acknowledgements
Contact: [email protected]
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