Transcript Wellingtontalk - University of Surrey

Water infusion and drug effusion in drug release
polymers and drug diffusion in mucosae and muscle
A S Clough, F E Gauntlett, M S Rihawy
University of Surrey
M Braden, M P Patel, QMW, London
J Booth, Astra- Zeneca, Macclesfield
A Cruchley, Royal London and St Barts Hospital
University of Surrey
Guildford
Surrey
England
Outline of Talk
• ION BEAM MICRO-ANALYSIS OF DIFFUSION
• WATER INGRESS INTO AND DRUG EGRESS
FROM IN-MOUTH POLYMERS
• WATER INGRESS INTO AND DRUG EGRESS
FROM CYLINDRICAL IN-BODY POLYMERS
• DRUG INGRESS INTO ORAL MUCOSAE
• DRUG DIFFUSION IN MUSCLE
• FUTURE WORK.
Ion Beam Analysis at Surrey 2 Years ago
Accelerator: 2MV Van de Graaff
Ion source: 3He
Scanning Micro-beam : Beam size 10m to 200m
Beam current - nA to A
Beam scan of up to 3mm  3mm.
V de G
Magnet
Object
aperture
Quadrupole focussing magnets
Computer controlled raster scanned
deflection plates
Scanning
microbeam target
chamber
LN2 cooled sample stage
Scanning Microbeam Target Chamber
Side view
Particle detectors
Front view of
sample stage
Cu blocks
X-ray
detector
Sample
Scanning zone
Focussed 3He
scanning microbeam
LN2 cooled sample stage
•NRA (Nuclear Reaction Analysis)
Protons detected from the reaction:
3He
+dp+
Q = 18.4 MeV
•Rutherford BackScattering (RBS)
•PIXE (Particle Induced X-ray Emission)
Water and drug profiles following water ingress into in-mouth planar
polymers
Water uptake and drug release have been characterised for:
•
chlorhexidine diacetate drug loadings of 0%,4.5%,9% and 15% of dry
weight polymer
•
3 polymers – Addition Cured silicone, Condensation Cured silicone and
PEM/THFM
•
2 immersion solutions – 90% pure H2O/10%D2O and 90% PBS/10%D2O
•
a series of 7 immersion times from 1 hour to 6 months
using three techniques:

scanning 3He ion microbeam NRA ,PIXE and backscattering to profile the
water ingress, correlate water and drug distributions and enable intersample normalisation

gravimetric measurements to establish absolute normalisation of water
uptake

UV measurements to establish mass of drug released to immersion
solution.
Sample Preparation
• Mix drug and silicone polymer, press into oblongs
20 mm  10 mm  ~1 mm.
• Immerse in 50 ml water (10% D2O/ 90%H2O) or
buffer solution (10% D2O/ 90% Buffer solution) at
37C
• Remove, hold between copper blocks on sample
plate, cut section at the block height; plunge in
LN2
• Mount sample plate on LN2 cooled sample stage
and do 3He beam scan
NRA Spectrum
14
12
Ln counts
10
RBS
Alphas
8
6
Protons
4
2
0
1
33 65 97 129 161 193 225 257 289 321 353 385 417 449 481 513 545
Channel Number
Drug-containing silicone polymer
exposed to 90%H2O/10% D2O at
37C
Cu
Al
Si
Cl
Example of an addition-cured polymer PIXE
spectrum, drug loading 4.5%, PBS immersion time
1 hour, displayed using a square vertical scale.
9% Drug loaded Addition Polymers, 2w exposure to PBS at 37 C
RBS
Silicon X-rays
Cl X-rays
Protons from
Deuterium
Rel conc (arb units)
1-d Diffusion Profiles of Water from 90%H2O/10%D2O
200
150
100
50
0
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
Polymer thickness (mm)
Addition cured Polymer
Condensation Cured Polymer
PEMA/THFM
1-d water diffusion profiles from 90%PBS/10%D2O
50
Addition Cured Polymer
25
Condensation Cured Polymer
100
75
0
80
130
180
230
Distance across polymer (mm)
50
PEMA/THFM
50
25
0
1h
60
110
160
210
260
DIstance across polymer (mm)
24h
25
336h
4036h
0
60
110
160
210
DIstance across polym er (m m )
260
6
9% Addition Water
9%Addition PBS
4
2
0
0
50
Water uptake as a percentage of
polymer mass
8
160
140
120
9% Condensation
Water
9% Condensation
PBS
100
80
60
40
20
0
100
0
Immersion Time^1/2 (hours^1/2)
Water uptake as a percentage of
polymer mass
Water uptake as a percentage of initial
polymer mass
10
180
Immersion Time^1/2
(hours^1/2)
16
14
12
10
9% PEM/THFM
Water
9% PEM/THFM
PBS
8
6
4
2
0
0
50
20
40
60
Immersion Time^1/2 (hours^1/2)
80
100
Drug Release and Water Uptake from
90%H2O/10%D2O at 37C
Addition Cured Silicone
Condensation Cured Silicone
PEMA/THFM
fraction of original drug
25
20
20
15
15
10
10
5
5
0
0
15
10
5
0
100 0
50
=
Time
Water uptake % of initial
polymer mass
20
1/2
20
60
80
0
)
20
Tim e
40
1/2
60
(Hour s
1/2
80
)
16
180
10
0
Tim e 1/2 (Hours 1/2)
1/2
(Hours
40
8
12
120
6
9% Add H2O
8
9% Condensation
Water
4
60
2
9% PEM/THFM
Water
4
0
0
20
40
60
Immersion Time^1/2 (hours^1/2)
80
0
0
20
40
60
Immersion Time^1/2 (hours^1/2)
80
0
0
20
40
60
Immersion Time^1/2 (hours^1/2)
80
Percentage of original drug
Drug Release and Water uptake from 90%
PBS/10%D2O at 37C
2.5
5
2
4
2.5
1.5
3
2
1
2
0.5
1
0
0
1.5
1
0
20
Time
40
1/2
(Hours
60
0.5
0
0
80
Time
1/2
)
Addition Cured
Water uptake as a percentage of
initial polymer mass
20
40
1/ 2
60
1/ 2
(Hours
0
80
Time
)
Condensation Cured
3
20
40
1/2
60
80
1/2
(Hours
)
PEMA/THFM
12
4.5
10
2
3
8
9% Addition PBS
6
9% PEM/THFM PBS
1
1.5
4
9% Condensation
PBS
2
0
0
0
0
20
40
60
Immersion Time^1/2 (hours^1/2)
80
0
20
40
60
Immersion Time^1/2 (hours^1/2)
80
0
20
40
60
Immersion Time^1/2 (hours^1/2)
80
% of Drug Released
Percentage of Original Drug released to the PBS
from a 9% Drug Loaded Condensation Cured
Silicone Polymer
5
4
3
2
1
0
0
20
Time
5.0000
1/2
40
1/2
(Hours )
60
80
40
60
80
0.0000
0
20
-5.0000
% of original polymer
mass lost
-10.0000
-15.0000
-20.0000
-25.0000
Immersion Time^1/2 (hours^1/2)
Cylindrical Polymer/Drug Depots
• Solid cylindrical depots (2.25 mm in diameter) of poly(dl-lactide)
P(DL)LA loaded with goserelin in ratios of 20%, 30% and 40% by
weight respectively were prepared by melt extrusion of
drug/polymer mixtures.
• Many sections 18 mm long were cut, weighed and immersed in
separate glass jars containing 45ml buffer solution mixed with 5ml
D2O. These were held at a constant temperature of 37C for times
between 1 hr and 7 days.
• On removal they were dried lightly with filter paper, weighed and
cut into sections 3mm long. These were transferred to the sample
plate, held at liquid nitrogen temperature and subsequently
scanned with the 3He ion microbeam – energy 1.3 MeV, diameter
10 microns, current ~ 1nA.
Cylindrical Polymers – colour scale normalised to 7 day 30% data
1 Hour
2
0
%
3
0
%
4
0
%
4 Hours
1 Day
4 Days
7 Days
Water diffusion into 40% drug loaded cylindrical
drug-release polymer from 90% PBS/ 10% D2O at
37C – colour scale normalised to 1d data
1hr
4hr
1d
4d
7d
Water Uptake of Drug Depots for Different Immersion Times
0,050
Water uptake (g)
0,040
20%
30%
40%
0,030
0,020
0,010
0,000
0
1
2
3
4
Immersion time (days)
5
6
7
Fractional Weight increase of Polymer after immersion
40
Fractional weight change (%)
35
30
25
20%
30%
40%
20
15
10
5
0
0
1
2
3
4
Immersion time (days)
5
6
7
Fraction of Drug Released
70
Fraction of drug released (%)
60
50
40
20%
30%
30
40%
20
10
0
0
1
2
3
4
Immersion time (days)
5
6
7
Ion Beam Analysis at Surrey Today
Present Accelerator: 2MV Tandetron
Ion source: 3He, 4He or protons
Scanning Microbeam : Beam size 1m to 200m
Beam current - nA to A
Beam scan of up to 2.5mm  2.5mm.
Nano beam (~10 nm
spot size) under
construction
Tandetron
Magnet
Object
aperture
External Scanning
microbeam (~ 10 microns
spot size)
Quadrupole focussing magnets
Computer controlled raster scanner
deflection plates
Scanning
microbeam target
chamber
LN2 cooled sample stage
Drug diffusion in pig mucosa
• Mucosa exposed to 10% solution of
chlorhexidine sulphate in water for 90
minutes
• Cut perpendicular to surface,
backcooled with LN2, and scanned
by 2 MeV, 2 micron spot size, proton
microbeam.
• Characteristic X-rays detected.
Flow Through Chamber
Cover slip prevents
evaporation of test
compound.
Reservoir of test compound
Threaded collar
allows tightening of
chamber without
disturbing tissue
Teflon chamber
Inlet port
Tissue
Viewing port
allows air bubbles
to be checked for.
Outlet port
Cross-section of mucosal epithelium
Cl distribution after 90
min exposure to
chlorhexidine sulphate
solution
K distribution after 90 min
exposure to chlorhexidine
sulphate solution
Direction of
Chlorhexidine
ingress
Chlorhexidine uptake distribution in mucosae for a dose time of 90 minutes.
Chlorine X-ray
counts
50
40
30
20
10
Depth (microns)
-2.5
-1
0.5
2
3.5
5
6.5
8
9.5
11
12.5
14
15.5
17
18.5
20
21.5
23
0
Fluorinated Drug Diffusion in porcine muscle tissue
Problem: Detecting fluorine at pp104 with microbeam currents (100pA)
and spatial resolution of 1 micron
Solution: Use 3.2 MeV ions and the reaction :
19F
(p, ) 16O*
Characteristic 6.05 MeV -rays detected with high efficiency hyperpure Germanium detector
Spectrum of  -rays from 19F (p, ) 16O*
N
 -Energy (MeV)
Fluorine Ingress Profile
80
normalised counts
70
60
50
40
30
20
10
0
0
50
100
150
distance (mm)
200
250
Work in progress
Diffusion of drugs that contain either fluorine or chlorine or are
deuterated into different biological tissues
Diffusion of water(labelled with deuterium) at low concentration
into resins and polymer films
Diffusion of chlorine and water into cements, mortars and
concrete
Development of nano-beam and associated detectors
Reactions Detected:
(iii) p + 11B   + 8Be
Q=8.582 MeV
100000
RBS

Counts
10000
1000
100
10
1
0
1
2
3
4
5
Energy (MeV)
Sensitivity Estimate : parts per 105
Spatial Resolution of Microbeam : ~ 1m
6
7
8
Reactions Detected:
(ii) p + 19F   + 16O
Q=8.114 MeV
100000
RBS
10000
Counts
RBS Pile-up

1000
100
10
1
1
2
3
4
5
6
Energy (MeV)
Sensitivity Estimate : parts per 104
Spatial Resolution of Microbeam : ~ 1m
7
8
9
The CdZnTe Array
• Connected in 3 groups of 4 detectors
• Outputs are summed together
Reactions Detected:
(i) 3He + D   + p
90
Q=18.352 MeV

80
p
70
Counts
60
50
40
30
20
10
0
1.5
4
6.5
9
Energy (MeV)
Sensitivity Estimate : parts per 104
Spatial Resolution of Microbeam : ~ 1m
11.5
14
The CdZnTe Detectors
•15mm x 15mm x 3mm
• can absorb the full energy of
protons up to ~15MeV
• pin connected to the front of the
detector is earthed, via a thin (50100nm) platinum contact layer
diffused onto the crystal surface
• other pin for signal
Array Solid Angle
The array is located ~1cm
upstream of the target and
subtends a useful solid angle
of ~/2 steradians (1/8
sphere).
(We are improving it to
allow a solid angle coverage
of  steradians).
Cutaway View:
ION BEAM
Addition 0% for various times in 90% H 2O/10% D 2O
200
water concentration (arbitrary units)
1 week
150
24 weeks
15 minutes
24 hours
100
50
0
-0.1
0.1
0.3
0.5
0.7
mm
0.9
1.1
1.3
Water Uptake of the Addition Cured Silicone Polymer Loaded with 0% Drug by weight for different immersion
times in PBS (90%H2O/ 10%D2O)
40
Water conc. (arbitrary units)
35
30
25
2 weeks
1 Day
20
4 Weeks
24 Weeks
15
10
5
0
80
100
120
140
160
Distance (mm)
180
200
220
240
2-d maps showing diffusion of deuterated water into a
planar glass sample - Scott 8330 exposed to 300 C D2O
Cu RBS map
Deuterium map
Si X-ray map
X-ray spectrum
1200
Cu from Cu blocks
1000
Counts
800
600
400
Si from polymer matrix
200
0
0
1
2
3
Energy (keV)
Drug –free polymer exposed to water at 37C
4
3He
backscatters
1d profile:
Addition 9% for various times in 90% H 2O/ 10% D 2O
200
Water concentration (arbitrary units)
15 minutes
150
1 week
24 weeks
24 hours
100
50
0
-0.1
0.1
0.3
0.5
0.7
mm
0.9
1.1
1.3
Addition 4.5% for various times in 90% H 2O/ 10% D 2O
200
1 week
24 weeks
water concentration (arbitrary units)
15 minutes
150
100
50
0
-0.1
0.1
0.3
0.5
0.7
mm
0.9
1.1
1.3
Addifiton 15% for various times in 90% H 2O/10% D 2O
200
1 week
24 weeks
15 minutes
Water concentration (arbitrary units)
24 hours
150
100
50
0
-0.1
0.1
0.3
0.5
0.7
mm
0.9
1.1
1.3
Water Uptake of the Addition Cured Silicone Polymer Loaded with 4.5% Drug by weight for different immersion
times in PBS (90%H2O/ 10%D2O)
40
35
water conc. (arb units)
30
25
2 Weeks
1 Days
20
4 Weeks
24 Weeks
15
10
5
0
80
100
120
140
160
Distance (mm)
180
200
220
240
Water Uptake of the Addition Cured Silicone Polymer Loaded with 9% Drug by weight for different immersion
times in PBS (90%H2O/ 10%D2O)
40
35
Water conc. (arbitrary units)
30
25
2 Weeks
1 Day
20
4 Weeks
24 Weeks
15
10
5
0
80
100
120
140
160
Distance across polymer (mm)
180
200
220
240
Water Uptake of the Addition Cured Silicone Polymer Loaded with 15% Drug by weight for different immersion
times in PBS (90%H2O/ 10%D2O)
40
35
2 Weeks
1 days
30
Water conc. (arbitrary units)
4 Weeks
24 Weeks
25
20
15
10
5
0
80
100
120
140
160
mm
180
200
220
240
Cl/Si X-ray ratio for 9% Addition and 9% Condensation Polymers
0.012
0.01
Cl/Si X-ray ratio
0.008
9% Condensation Polymer
0.006
9% Addition Polymer
0.004
0.002
0
0
10
20
30
tim e 1/2 (hours 1/2)
40
50
60
0.0152
Cl X-ray/Si X-ray Intensity Ratio
0.0114
15%
0.0076
9%
4.50%
0%
0.0038
0
0
10
20
30
Time
1/2
40
(hours
1/2
)
Cl/Si Ratio for Addition-Cured Polymer
50
60
0.8
Absolute concentration of water (g cm-3)
0.7
1 hour
4 hours
1 day
4 days
7 days
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
0.2
0.4
0.6
0.8
Radial distance (mm)
1
1.2
1.4
Absolute concentration of water (g cm-3)
0.6
1 hour
4 hours
1 day
4 days
7 days
0.5
0.4
0.3
0.2
0.1
0.0
0
0.2
0.4
0.6
0.8
Radial distance (mm)
1
1.2
1.4
Graph Showing the % Drug Mass Released and % Polymer Mass Loss for the Condensation Cured
Silicone Polymer at a drug loading of 9% for Varying Immersion Times in a PBS Solution
6.0000
4.0000
2.0000
0.0000
0
10
20
30
40
50
60
70
-2.0000
% of original drug released
% of original polymer mass lost
-4.0000
-6.0000
-8.0000
-10.0000
-12.0000
Immersion Time^1/2 (hours^1/2)
Graph Showing the % Polymer Mass Loss for the
Condensation Cured Silicone Polymer at a drug
loading of 9% for Varying Immersion Times in a PBS
Solution
5.0000
0.0000
-5.0000
0
20
40
60
80
% of original polymer
mass lost
-10.0000
-15.0000
-20.0000
-25.0000
Immersion Time^1/2 (hours^1/2)
S distribution after 90 min
exposure to chlorhexidine
sulphate solution
P distribution after 90 min
exposure to chlorhexidine
sulphate solution
Cl distribution after 90 min
exposure to chlorhexidine
sulphate solution
S distribution after 90 min
exposure to chlorhexidine
sulphate solution
Direction of
Chlorhexidine
ingress