orthogonal imaging jan 2012

www.paraytec.com

S y s t e m s f o r L i f e S c i e n c e R e s e a r c h

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Orthogonal four dimensional imaging:

Rapid development of products

using flow through laminar device

Jim Lenke

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Can changing your perspective Can changing your perspective... improve getting more into the water?

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Measurement

Reaction

Relocate the detector onto the reaction zone – see more!

Measurement Reaction

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•System Operation

•Recent data

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System operation

Programmable

Digital temp control

Software controlled

Programmable pump

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Camera

Pulsed Xenon lamp

Single

wavelength

filter

UV flash lamp

Recording movies in the UV/ VIS

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SDI 300 simplified

J. Østergaard et. Al. Pharm. Res. (2010) 27:2614

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Laminar flow

A B Front view

Laminar flow creates a steady state where the donor concentration

(boundary layer) can be controlled with flow rate. Thereby enabling

probing of the solid-liquid interface in real-time.

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System operation

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Buffer flow ml/min

Solvate particles Move molecules

Mass F

lux

dete

ctio

n z

one

Sample Cup

Surface area

0.0314 cm2

Absorbance *Flow/Surface area =

Intrinsic dissolution rate (IDR) (mg/ml)*(ml/ min)/(cm2)= mg/min/ cm2

Measure

Absorbance

3 easy steps to measure IDR

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Flow (ml/min) IDR (mg/min/cm2)

Buffer capacity

Compression force

Surface energy

pH pKa

Factors influencing laminar-IDR

IDR (mg/min/cm2)

Buffer capacity

Surface energy

pH

pKa

Flow rate

Compression

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Flow through IDR: Viewing dissolution at the surface

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Obvious increase in release in Organic environment

Nicotine release from patch

100%

Phosphate

50%

Phosphate/

50% ACN

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Nicotine release improvement

0

20

40

60

80

100

120

140

160

180

200

0.00 5.00 10.00 15.00 20.00

AU

C (

mm

*A

U)

Time (min)

AUC vs. time

100% PBS

50% CAN/PBS

Linear (100% PBS)

Linear (50% CAN/PBS)

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Diffusion rate

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25 30

AU

C (m

M *

mm

)

Time (min)

Diffusion vs. pH : Furosemide

pH 1.2

pH 4.5

pH 6.8

0

200

400

600

800

1000

1200

0 5 10 15 20 25 30

AU

C (

mM

*m

m)

Time (min)

Diffusion vs. pH: Ketoprofen

pH 1.2

pH 4.5

pH 6.8

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.2 0.4 0.6 0.8 1

Co

nce

ntr

atio

n (

mM

)

Vertical distance (mm)

Ketoprofen: Concentration profile vs. pH @ 0.2 ml/min

pH 6.8

pH 4.5

pH 1.2

How fast will a constant surface area achieve equilibrium in a static, small volume vessel?

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Crystalline

Amorphous co-precipitate

Diffusion height tracks IDR values

Visualizing IDR

3 decreasing flow rates (0.8, 0.4, 0.2 ml/min )

followed by no flow step.

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IDR vs. Flow rate

y = 0.0186x - 0.0003 R² = 0.9995

y = -0.018x2 + 0.0152x + 0.023 R² = 1

y = -0.009x2 + 0.0101x + 0.0338 R² = 1

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0 0.1 0.2 0.3 0.4 0.5 0.6

IDR

(mg/

min

/cm

^2

)

flow rate (ml/min)

IDR vs. Flow

Flat profile suggests swelling which

‘controls’ dissolution

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Cumulative mass loss per time. Time IDR SD CV

0 0.0304 0.0028 9.2%

1 0.0316 0.0021 6.6%

2 0.0327 0.0021 6.4%

3 0.0315 0.0020 6.3%

4 0.0319 0.0022 6.9%

5 0.0322 0.0022 6.8%

6 0.0321 0.0021 6.5%

7 0.0328 0.0022 6.7%

8 0.0328 0.0020 6.1%

9 0.0329 0.0020 6.1%

10 0.0327 0.0021 6.4%

11 0.0327 0.0021 6.4%

12 0.0330 0.0019 5.8%

13 0.0326 0.0021 6.4%

14 0.0324 0.0022 6.8%

15 0.0321 0.0020 6.2%

16 0.0312 0.0019 6.1%

avg 0.0322 0.0021 6.6%

std 0.0007 0.0002 0.0074

rsd 2.19% 9.48% 11.28%

32.2 ±0.7 µg/min/cm2

y = 0.00101x R² = 0.99984

y = 0.00099x R² = 0.99957

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0 2 4 6 8 10 12 14 16 18

Mas

s (

mg)

Time ( min)

Mass loss per time

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Sample prep influence on IDR

AAPS 2011 Poster: Advances in Novel Dissolution Imaging to Measure IDR rates of Polymorphic API’s.

W. Hulse, J. Gray, R. Forbes, Biopharmaceutical Formulation Group,

University of Bradford, UK

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Sub-surface changes in IDR

As buffer seeps into powder, sub-surface

changes take place, such as pH or

morphology from interacting with buffer.

Typical poorly soluble compounds remove

microns/minute so as new surface becomes

available it’s different.

Wetability and morphology changes are

important factors in API development.

Void pockets = little stagnant reservoirs

Sample

Density Wall

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Release from Sediment

Visible - no molecular

absorbance

UV – ONLY molecular

absorbance

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GI simulation: Mimic continuous pH changes

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0

20

40

60

80

100

120

0 5 10 15 20 25 30 35

% b

uff

er

Time (min)

3 pH gradient profile

A

B

C

A= pH 1.5 B= pH 4.5 C= pH 6.8

A B

C

Variable pH IDR (mimic GI)

effluent

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Rapid evaluation of multiple pH pH 1.2

pH 4.5

pH 6.8

Ketoprofen 0.2 ml/min

sample

2.5

mm

0.0000

0.0040

0.0080

0.0120

0.0160

0.0200

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000

0.3500

0 11 22 33

Cu

mu

lati

ve m

ass

(mg)

Cu

mu

lati

ve m

ass

(mg)

Time (min)

Cumulative mass vs. pH @ 0.2 ml/min

Atenolo (pKa 8.9)

Ketoprofen(pKa 4.3)

Furosemide

pH 1.2

pH 4.5

pH 6.8

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IDR vs. pH Ketoprofen

Furosemide

Single experiment, better understanding

•(1) sample

•(1) contious flow rate

•(3) pH buffers

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Conclusion:

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Orthogonal flow through imaging

• Fast and small

o 2-7 mg/run with only 10 ml buffer in less than 20 min

• Able to measure more than just IDR

o IDR vs. flow, IDR vs. pH, diffusion rate, diffusion boundary layer

• GI modeling potential

o Understand how pH affects IDR

Get more into the water by changing your view!

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Publications 1. Insights into the Early Dissolution Events of Amlodipine Using UV Imaging

and Raman Spectroscopy, J. Boetker et. al. Mol. Pharm. (2011)

dx.doi.org/10.1021/mp200205z

2. Pharmaceutical Dissolution and UV Imaging, S.Wren, J. Lenke, American

Laboratory (2011)

3. Monitoring Lidocaine Single-Crystal Dissolution by Ultraviolet Imaging, J.

Østergaard et. al. J. Pharm. Sci. (2011) DOI 10.1002/jps.22532

4. Realtime UV-imaging of Nicotine Release from Transdermal Patch, J.

Østergaard, Pharm. Res (2010) 27:2614–2623 DOI 10.1007/s11095-010-

0257-9

www.paraytec.com

S y s t e m s f o r L i f e S c i e n c e R e s e a r c h

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Thanks to:

•Prof. R. Forbes, University of Bradford

•Prof. J. Østergaard, University Copenhagen

•Prof. N. Fotaki, University of Bath

•Dr. S. Wren, AstraZeneca (UK)

jim.lenke@paraytec.com

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Additional Material

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IDR vs. Flow rate

y = 0.0186x - 0.0003 R² = 0.9995

y = -0.018x2 + 0.0152x + 0.023 R² = 1

y = -0.009x2 + 0.0101x + 0.0338 R² = 1

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0 0.1 0.2 0.3 0.4 0.5 0.6

IDR

(mg/

min

/cm

^2

)

flow rate (ml/min)

IDR vs. Flow

IDR at multiple flows provides a better fingerprint of performance-

particularly at physiological linear velocities

3 formulations @

• 3 flow rates

•Identical buffer

•Identical compression

Flat profile suggests swelling which

‘controls’ dissolution

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Particle dissolving rate from IDR

Know that average density = 12 mg/ 2.4 mm

or 5 µg / µm

From average density, can calculate time

needed to dissolve particle.

Time = ( Thickness X Density) / DR

={(163 µm) x (5 µg / µm)} / (µg /min)

Ex: (815µg)/ 14 µg /min = 58 min

Convert surface area (3.14 x 10 ^6 um2)

into sphere: A particle that is: Diameter = 1000 µm ( 1.0 mm) Volume = 5.1 x 10^8 µm 3

Thickness equivalent to particle volume = Vol/ Area= 163 µm

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In-situ surface pH Measurements

UV pH Dye

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Buffer Capacity: Ketoprofen

50 mM NaH2PO4 pH 6.5

530 nm; Methyl red in buffer;

10 mM NaH2PO4 pH 6.5

Water

Observing in-situ surface pH at

different buffering capacities

provides insight into biorelevant

media performance if surface pH

is altered in standard aqueous media.

**pKa = 4.2

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Atenolol: Surface pH

UV( 254 nm) pH 4.5 50 mM NaH2PO4

Flow = 0.6,

Phenolphtalein (530 nm) pH 4.5 50 mM NaH2PO4

Flow = 0.6

•Rapidly soluble Atenolol ( pKa 9.2) dissolves fast enough to drastically change pH and

amount of ionized API. Dark red in top picture near detector saturation, but important

measurement is thickness of diffusion boundary layer ( Red > Blue).

**pKa= 9.2

Act P x Sensor stand

Quick couple

fittings Imaging

area

Cut away view

Single wavelength UV light passes through

flow cell across sample

Flow cell sits over the camera

Flow cell orientation

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Surface availability

Towards center

Z axis

Surface concentration

Boundary layer

Convective loss

At lower flow rates more material

reaches center stream, farther

away from wall.

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Effluent concentration or ‘dynamic Solubility’

y = 10x + 3E-15

y = 20x + 5E-15

0

10

20

30

40

50

60

70

0 0.5 1 1.5 2 2.5 3 3.5

IDR

( m

g/m

in/c

m^

2)

Flow rate (ml/min)

Solubility and flow rate

API 1

API 2

solubility API 1

solubility API 2

Linear (API 1)

Linear (API 2)

Running a single sample experiment* at different flow rates offers a plot of IDR vs.

flow rate.

(IDR) / (flow rate) = solubility

(mg/min) / (ml/min) = mg/ml

API 2

API 1

Solubility API 1

In Vitro Dynamic Solubility Test: Influence of Various Parameters Sylvie Thelohan and Alain de Meringo

Environ Health Perspect 1 02(Suppl 5):91-96 (1994)

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dynamic Solubility

0.030

0.035

0.040

0.045

0.050

0.055

0.060

0.065

0.070

0.075

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Solu

bil

ity

(mg/

ml)

IDR

(m

g/m

in/c

m^

2)

Flow rate (ml/min)

IDR and dynamic Solubility vs. flow rate

IDR

Solubility

Fa

st

Fe

d

Can effluent concentration from flow through device be successfully used to predict available concentration?

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dynamic Solubility

Comparison of effluent concentration and calculated dynamic solubility

Strong correlation.

y = 0.0799x-0.473 R² = 0.9994

y = 0.0533x-1.063 R² = 0.9964

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.065

0.085

0.105

0.125

0.145

0.165

0.185

0.205

0.225

0.245

0.265

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Cal

cula

ted

dS

(mg/

ml)

Effl

ue

nt

Co

nce

ntr

atio

n (m

g/m

l)

Flow rate (ml/min)

comparison of effluent and dS

effluent

dS

Power (effluent)

Power (dS)

Implies decrease with increasing flow rate, however………..

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2 ml/min

0.5 ml/min

0.2 ml/min

0.1 ml/min

0.05 ml/min

a)

b)

c)

d)

e)

Radial distribution in GI

Stagnant layer –aqueous boundary layer

Injections from HPLC into flow cell shows rate, amount and time at Lumen wall vs. flow rate. Shown with Caffeine at different flow rates.

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Radial distribution in GI

Stagnant layer –aqueous boundary layer

Injections from HPLC into flow cell shows rate, amount and time at wall vs. flow rate. Shown at 0.5 & 0.05 ml/min flow rates.

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GI Fluid dynamics

Can these technique be used in a predictive manner to

close the gap between in-vitro and in-vivo correlation?

Z axis

Z axis

X axis

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Measurement location

3-Dimensional data ( intensity over X-Z) over time= 4 Dimensional data

True sample-liquid interface measurements

vx

z

Detector

Flow (ml/min)

Downstream absorbance

measure

X axis

Z axis Downstream measure zone

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Press operation

Sample cup

Dissolution face

Compression rod

Top plate

Sample plate

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Powder sample compression

Automatically aligned

sample cup

Load sample powder. Compress using reproducible

torque wrench

Quality of sample surface

depends on face

Image of sample cup

surface after compressing

powder

Other experiments can be carried out on surface before

and after dissolution analysis!!

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Linear velocity related to App4 SDI APP 4 APP 4

Sectional area

(cm2)

0.14 11.3 22.6

Flow rate (ml/min)

0.1 0.7 0.1 0

0.2 1.4 0.2 0

0.4 2.9 0.4 0.1

0.8 5.7 0.8 0.2

1.2 8.6 1.2 0.3

2.0 14.3 2.0 0.5

4.0 28.6 4.0 1.0

8.0 57.1 8.0 2.0

16 114 16.0 4.0

32 227 32.0 8.0

Time (min) 60 270 420 Total(mL)

Flow rate

(ml/min)

SDI 0.2 12 54 84 150

App 4 1.2 72 324 504 900

App 4 4.0 240 1080 1680 3000

Linear velocity range

compared to App 4 device.

Covers same physiological

range using less volume.

Additional benefit from

no-flow measurements

12.5 hrs uses only 150 ml

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Highly stable process

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.07 0.14 0.21 0.28 0.35 0.42 0.49 0.56 0.63 0.7

Ab

sorb

ance

(A

U)

Z Distance (mm)

Absorbance profile vs. time:

0

2

4

6

8

10

12

14

16

Profile over 17 min at constant flow.

• Time zero (blue line) shows pump start.

210 µm

0.14 0.15 0.16 0.17 0.18 0.19 0.2 0.21

Time IDR SD CV

0 0.0304 0.0028 9.2%

1 0.0316 0.0021 6.6%

2 0.0327 0.0021 6.4%

3 0.0315 0.0020 6.3%

4 0.0319 0.0022 6.9%

5 0.0322 0.0022 6.8%

6 0.0321 0.0021 6.5%

7 0.0328 0.0022 6.7%

8 0.0328 0.0020 6.1%

9 0.0329 0.0020 6.1%

10 0.0327 0.0021 6.4%

11 0.0327 0.0021 6.4%

12 0.0330 0.0019 5.8%

13 0.0326 0.0021 6.4%

14 0.0324 0.0022 6.8%

15 0.0321 0.0020 6.2%

16 0.0312 0.0019 6.1%

avg 0.0322 0.0021 6.6%

std 0.0007 0.0002 0.0074

rsd 2.19% 9.48% 11.28%

32.2 ±0.7 µg/min/cm2

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IDR vs. time: A Change ? Time IDR SD CV

0 0.0304 0.0028 9.2%

1 0.0316 0.0021 6.6%

2 0.0327 0.0021 6.4%

3 0.0315 0.0020 6.3%

4 0.0319 0.0022 6.9%

5 0.0322 0.0022 6.8%

6 0.0321 0.0021 6.5%

7 0.0328 0.0022 6.7%

8 0.0328 0.0020 6.1%

9 0.0329 0.0020 6.1%

10 0.0327 0.0021 6.4%

11 0.0327 0.0021 6.4%

12 0.0330 0.0019 5.8%

13 0.0326 0.0021 6.4%

14 0.0324 0.0022 6.8%

15 0.0321 0.0020 6.2%

16 0.0312 0.0019 6.1%

avg 0.0322 0.0021 6.6%

std 0.0007 0.0002 0.0074

rsd 2.19% 9.48% 11.28%

32.2 ±0.7 µg/min/cm2

1.75

2.00

2.25

2.50

2.75

30.25

30.50

30.75

31.00

31.25

31.50

31.75

32.00

32.25

32.50

32.75

33.00

33.25

0 2 4 6 8 10 12 14 16 18

Stan

dar

d D

evi

atio

n

IDR

(µg/

min

/cm

^2

)

Time (min)

IDR vs. time

µg/min IDR

Std. Dev.

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Minimum flow step

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 15 30 45

3 m

in C

um

ula

tive

mas

s (m

g)

Cu

mu

lati

ve m

ass(

mg)

Time (min)

Cumulative mass vs. pH: Ketoprofen

pH 6.8

pH 4.5

pH 1.2

3 min step pH 6.8

3 min pH 4.5

3 min pH 1.2

Equivalent rank order values can be found with as little as 3 min when compared to 15 min step.