polymers and drug diffusion in mucosae and muscle

reelingripebeltUrban and Civil

Nov 15, 2013 (3 years and 8 months ago)

68 views

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:
3
He

Scanning Micro
-
beam : Beam size 10

m

瑯′〰

m

††† †††


††† ††
䉥慭B捵牲敮琠
-

湁⁴

A




Beam scan of up to 3mm


㍭3.


Magnet

Computer controlled raster scanned
deflection plates

Quadrupole focussing magnets

V de G

Object

aperture

LN
2
cooled sample stage

Scanning
microbeam target
chamber

Side view

Front view of

sample stage

Particle detectors

LN
2

cooled sample stage

Focussed
3
He

scanning microbeam

X
-
ray

detector

Scanning zone

Cu blocks

Sample

Scanning Microbeam Target Chamber


NRA (Nuclear Reaction Analysis)


Protons detected from the reaction:



3
He + d


瀠⬠

††††
儠㴠ㄸ⸴⁍敖



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 H
2
O/10%D
2
O and 90% PBS/10%D
2
O


a series of 7 immersion times from 1 hour to 6 months

using three techniques:


scanning
3
He ion microbeam NRA ,PIXE and backscattering to profile the
water ingress, correlate water and drug distributions and enable inter
-
sample 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% D
2
O/ 90%H
2
O) or
buffer solution (10% D
2
O/ 90% Buffer solution) at
37C


Remove, hold between copper blocks on sample
plate, cut section at the block height; plunge in
LN
2


Mount sample plate on LN
2

cooled sample stage
and do
3
He beam scan


0
2
4
6
8
10
12
14
1
33
65
97
129
161
193
225
257
289
321
353
385
417
449
481
513
545

Ln counts

Channel Number

Protons

Alphas

RBS

NRA Spectrum

Drug
-
containing silicone polymer
exposed to 90%H
2
O/10% D
2
O at
37C

Cu


Cl


Si


Al






















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

0
50
100
150
200
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
Polymer thickness (mm)
Rel conc (arb units)
1
-
d Diffusion Profiles of Water from 90%H
2
O/10%D
2
O

Addition cured Polymer

Condensation Cured Polymer

PEMA/THFM

0
25
50
80
130
180
230
D i s t a n c e a c r o s s p o l y m e r ( m m )
0
25
50
75
100
60
110
160
210
260
D I s t a n c e a c r o s s p o l y m e r ( m m )
0
25
50
60
110
160
210
260
D I s t a n c e a c r o s s p o l y m e r ( m m )
1 h
2 4 h
3 3 6 h
4 0 3 6 h

1
-
d water diffusion profiles from 90%PBS/10%D
2
O

Addition Cured Polymer

Condensation Cured Polymer

PEMA/THFM

0
20
40
60
80
100
120
140
160
180
0
50
100
Immersion Time^1/2
(hours^1/2)
Water uptake as a percentage of
polymer mass
9% Condensation
Water
9% Condensation
PBS
0
2
4
6
8
10
0
50
100
Immersion Time^1/2 (hours^1/2)
Water uptake as a percentage of initial
polymer mass
9% Addition Water
9%Addition PBS
0
2
4
6
8
10
12
14
16
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
Water uptake as a percentage of
polymer mass
9% PEM/THFM
Water
9% PEM/THFM
PBS
0
5
10
15
20
0
50
100
Time
1/2
(Hours
1/2
)
fraction of original drug
0
5
10
15
20
25
0
20
40
60
80
Time
1/2
(Hours
1/2
)
0
5
10
15
20
0
20
40
60
80
Time
1/2
(Hours
1/2
)
Addition Cured Silicone




Condensation Cured Silicone PEMA/THFM


0
4
8
12
16
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
9% PEM/THFM
Water
0
60
120
180
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
9% Condensation
Water
=
0
2
4
6
8
10
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
Water uptake % of initial
polymer mass
9% Add H2O
Drug Release and Water Uptake from

90%H
2
O/10%D
2
O at 37C


Addition Cured


Condensation Cured



PEMA/THFM


0
0.5
1
1.5
2
2.5
0
20
40
60
80
Time
1/2
(Hours
1/2
)
Percentage of original drug
0
1
2
3
4
5
0
20
40
60
80
Time
1/2
(Hours
1/2
)
0
0.5
1
1.5
2
2.5
0
20
40
60
80
Time
1/2
(Hours
1/2
)
0
1
2
3
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
Water uptake as a percentage of
initial polymer mass
9% Addition PBS
0
2
4
6
8
10
12
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
9% Condensation
PBS
0
1.5
3
4.5
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
9% PEM/THFM PBS
Drug Release and Water uptake from 90%


PBS/10%D
2
O at 37C

Percentage of Original Drug released to the PBS
from a 9% Drug Loaded Condensation Cured
Silicone Polymer
0
1
2
3
4
5
0
20
40
60
80
Time
1/2
(Hours
1/2
)
% of Drug Released
-25.0000
-20.0000
-15.0000
-10.0000
-5.0000
0.0000
5.0000
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
% of original polymer
mass lost

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
D
2
O. 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
3
He ion microbeam


energy 1.3 MeV, diameter
10 microns, current ~ 1nA.


2
0
%

3
0
%

4
0
%

1 Hour

4 Hours

1 Day

4 Days

7 Days

Cylindrical Polymers


colour scale normalised to 7 day 30% data


1hr 4hr 1d 4d 7d

Water diffusion into 40% drug loaded cylindrical
drug
-
release polymer from 90% PBS/ 10% D
2
O at
37C


colour scale normalised to 1d data

0,000
0,010
0,020
0,030
0,040
0,050
0
1
2
3
4
5
6
7
Immersion time (days)
Water uptake (g)
20%
30%
40%
Water Uptake of Drug Depots for Different Immersion Times

0
5
10
15
20
25
30
35
40
0
1
2
3
4
5
6
7
Immersion time (days)
Fractional weight change (%)
20%
30%
40%
Fractional Weight increase of Polymer after immersion

0
10
20
30
40
50
60
70
0
1
2
3
4
5
6
7
Immersion time (days)
Fraction of drug released (%)
20%
30%
40%

Fraction of Drug Released

Ion Beam Analysis at Surrey Today

Present Accelerator: 2MV Tandetron

Ion source:
3
He,
4
He 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.


Magnet

Computer controlled raster scanner
deflection plates

Quadrupole focussing magnets

Tandetron

Magnet

Object

aperture

LN
2
cooled sample stage

Scanning
microbeam target
chamber

External Scanning
microbeam (~ 10 microns
spot size)

Nano beam (~10 nm
spot size) under
construction

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.


Reservoir of test compound

Threaded collar

allows tightening of

chamber without

disturbing tissue

Outlet port

Tissue

Inlet port

Teflon chamber

Viewing port

allows air bubbles

to be checked for.

Cover slip prevents

evaporation of test

compound.

Flow

Through Chamber



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.
0
10
20
30
40
50
23
21.5
20
18.5
17
15.5
14
12.5
11
9.5
8
6.5
5
3.5
2
0.5
-1
-2.5
Depth (microns)
Chlorine X-ray
counts
Fluorinated Drug Diffusion in porcine muscle tissue

Problem: Detecting fluorine at pp10
4

with microbeam currents (100pA)
and spatial resolution of 1 micron

Solution: Use 3.2 MeV ions and the reaction :




19
F (p,

)
16
O
*


Characteristic 6.05 MeV

-
rays detected with high efficiency hyper
-
pure Germanium detector




-
Energy (MeV)

N


Spectrum of


-
rays from
19
F (p,

)
16
O
*



Fluorine Ingress Profile
0
10
20
30
40
50
60
70
80
0
50
100
150
200
250
distance (mm)
normalised counts



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 +
11
B






8
Be



Q=8.582 MeV

Sensitivity Estimate : parts per 10
5

Spatial Resolution of Microbeam : ~ 1

m

1
10
100
1000
10000
100000
0
1
2
3
4
5
6
7
8
Energy (MeV)
Counts
RBS



Reactions Detected:







(ii)
p +
19
F





16
O



Q=8.114 MeV

Sensitivity Estimate : parts per 10
4

Spatial Resolution of Microbeam : ~ 1

m

1
10
100
1000
10000
100000
1
2
3
4
5
6
7
8
9
Energy (MeV)
Counts
RBS

RBS Pile
-
up





Connected in 3 groups of 4 detectors



Outputs are summed together

The CdZnTe Array

Reactions Detected:







(i)
3
He + D




⬠p



Q=18.352 MeV

0
10
20
30
40
50
60
70
80
90
1.5
4
6.5
9
11.5
14
Energy (MeV)
Counts
Sensitivity Estimate : parts per 10
4

Spatial Resolution of Microbeam : ~ 1

m



p



can absorb the full energy of
protons up to ~15MeV



pin connected to the front of the
detector is earthed, via a thin (50
-
100nm) platinum contact layer
diffused onto the crystal surface


15mm x 15mm x 3mm



other pin for signal

The CdZnTe Detectors

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).

ION BEAM

Cutaway View:

Array Solid Angle

Addition 0% for various times in 90% H
2
O/10% D
2
O
0
50
100
150
200
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
mm
water concentration (arbitrary units)
1 week
24 weeks
15 minutes
24 hours
Water Uptake of the Addition Cured Silicone Polymer Loaded with 0% Drug by weight for different immersion
times in PBS (90%H2O/ 10%D2O)
0
5
10
15
20
25
30
35
40
80
100
120
140
160
180
200
220
240
Distance (mm)
Water conc. (arbitrary units)
2 weeks
1 Day
4 Weeks
24 Weeks
2
-
d maps showing diffusion of deuterated water into a
planar glass sample
-

Scott 8330 exposed to 300

C D
2
O

Deuterium map

Si X
-
ray map

Cu RBS map

X
-
ray spectrum

0
200
400
600
800
1000
1200
0
1
2
3
4
Energy (keV)
Counts
Si from polymer matrix

Cu from Cu blocks

Drug

free polymer exposed to water at 37C

3He
backscatters

Addition 9% for various times in 90% H
2
O/ 10% D
2
O
0
50
100
150
200
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
mm
Water concentration (arbitrary units)
15 minutes
1 week
24 weeks
24 hours
1d profile:

Addition 4.5% for various times in 90% H
2
O/ 10% D
2
O
0
50
100
150
200
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
mm
water concentration (arbitrary units)
1 week
24 weeks
15 minutes
Addifiton 15% for various times in 90% H
2
O/10% D
2
O
0
50
100
150
200
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
mm
Water concentration (arbitrary units)
1 week
24 weeks
15 minutes
24 hours
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)
0
5
10
15
20
25
30
35
40
80
100
120
140
160
180
200
220
240
Distance (mm)
water conc. (arb units)
2 Weeks
1 Days
4 Weeks
24 Weeks
Water Uptake of the Addition Cured Silicone Polymer Loaded with 9% Drug by weight for different immersion
times in PBS (90%H2O/ 10%D2O)
0
5
10
15
20
25
30
35
40
80
100
120
140
160
180
200
220
240
Distance across polymer (mm)
Water conc. (arbitrary units)
2 Weeks
1 Day
4 Weeks
24 Weeks
Water Uptake of the Addition Cured Silicone Polymer Loaded with 15% Drug by weight for different immersion
times in PBS (90%H
2
O/ 10%D
2
O)
0
5
10
15
20
25
30
35
40
80
100
120
140
160
180
200
220
240
mm
Water conc. (arbitrary units)
2 Weeks
1 days
4 Weeks
24 Weeks

Cl/Si X-ray ratio for 9% Addition and 9% Condensation Polymers
0
0.002
0.004
0.006
0.008
0.01
0.012
0
10
20
30
40
50
60
time
1/2
(hours
1/2
)
Cl/Si X-ray ratio
9% Condensation Polymer
9% Addition Polymer
Cl/Si Ratio for Addition-Cured Polymer
0
0.0038
0.0076
0.0114
0.0152
0
10
20
30
40
50
60
Time
1/2
(hours
1/2
)
Cl X-ray/Si X-ray Intensity Ratio
15%
9%
4.50%
0%
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Radial distance (mm)
Absolute concentration of water (g cm
-3
)
1 hour
4 hours
1 day
4 days
7 days
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Radial distance (mm)
Absolute concentration of water (g cm
-3
)
1 hour
4 hours
1 day
4 days
7 days
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
-12.0000
-10.0000
-8.0000
-6.0000
-4.0000
-2.0000
0.0000
2.0000
4.0000
6.0000
0
10
20
30
40
50
60
70
Immersion Time^1/2 (hours^1/2)
% of original drug released
% of original polymer mass lost
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
-25.0000
-20.0000
-15.0000
-10.0000
-5.0000
0.0000
5.0000
0
20
40
60
80
Immersion Time^1/2 (hours^1/2)
% of original polymer
mass lost
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