Correlation of human and biorelevant media solubility for poorly soluble compounds

Patrick AugustijnsNottingham, September 12 2012

Low solubility: a growing problem

More lipophilic

- HTS

- Combinatorial chemistry

- More lipophilic targets

More solubility issues

- Higher risk of failing during early or late development.- Appropriate solubility measurements necessary

06/06/2012

Pharmaceutical profiling - Solubility

3

Van Herwaarden et al., Trends Pharmacol. Sci. 2009

Disintegration

Dissolution

Permeation

SolubilityAbsorption

Overview

• Intestinal drug behavior

Solubility

Supersaturation

Definition

• Solubility: The maximum quantity of a substance that can be completely dissolved in a given amount of solvent.

– Solvent used and its composition– Temperature– pH– Degradation– Solid state (polymorph type)– Aggregation– Counter ions (salts)– Ionic strength

Determination of thermodynamic solubility

• Thermodynamic solubility (equilibrium solubility):

– starting with crystalline material– equilibrium with solid compounds (time consuming)– 24-48h timescale

C

t

Disruption of Dissolution

crystal lattice

Determination of kinetic solubility

• Kinetic Solubility: precipitation from organic solvent

- Appropriate up to lead optimization- Solubility data are time-dependent- Likely to overpredict thermodynamic solubility

Supersaturation

Precipitation

C

t

- DMSO

- Ethanol

- Dimethoxyethane

06/06/2012

Thermodynamic solubility• Crystalline material

• Equilibrium with solid form

• Shake flask method

Pharmaceutical profiling - Solubility

Put excess ofcompound in Eppendorftube

Add solvent Shake for 24hat 37°C

Centrifugefor 15min

at14000rpm

Analysesupernatans

withHPLC

8

C

t

Key questions

• Which solvent systems?

0

1

2

3

4

5

6

7

8

9

10

µM

Phosphate Buffer pH = 6

SGF

pH = 1

FaSSIFFeSSIF

Fasted HIF

Solubility of Itraconazole in different solvent systems

Biorelevance of solubility assays

in vivo in vitro

BS

PL + LP DD

Intraluminal conditionsIntroduction

fasted ↔ fed state:

1)pH (↓)

2)Bile salts (↑)

3)Biliary Phospholipids (↑)

4)Dietary digestion products

• Lipolytic digestion products

=> Mixed micelles

Collection of HIF

Aspiration state (duodenum)

Fasted Fed Fat-enriched fed

Administration of liquid meal

250 ml water 400 ml Ensure Plus+ 250 ml water

300 ml Scandishake Mix+ 350 ml water

Fat content 30% 46%

Energy content 600 kcal 600 kcal

Collection period 2h 5h 5h

Used for:

characterizationin vitro solubility

0 30 60 90 120 150 180 210 240 270 3002

4

6

8

10

collection time (min)

pH

pH

fasted

fat-enriched fed

fed

0 30 60 90 120 150 180 210 240 270 3002

4

6

8

10

collection time (min)

pH

0 30 60 90 1202

4

6

8

10

S1S2S3S4S5

collection time (min)

pH

Bile salts

0 30 60 90 1200

5

10

15

20

25

30

35

S1S2S3S4S5

collection time (min)

tota

l bile

sal

t con

c (m

M)

0 30 60 90 120 150 180 210 240 270 3000

5

10

15

20

25

30

35

collection time (min)

tota

l bile

sal

t con

c (m

M)

0 30 60 90 120 150 180 210 240 270 3000

5

10

15

20

25

30

35

collection time (min)

tota

l bile

sal

t con

c (m

M)

fasted

fat-enriched fed

fed

Phospholipids

0 30 60 90 1200

2

4

6

8

10

S1S2S3S4S5

collection time (min)

tota

l pho

spho

lipid

con

c (m

M)

0 30 60 90 120 150 180 210 240 270 3000

2

4

6

8

10

collection time (min)

tota

l pho

spho

lipid

con

c (m

M)

0 30 60 90 120 150 180 210 240 270 3000

2

4

6

8

10

collection time (min)

tota

l pho

spho

lipid

con

c (m

M)

fasted

fat-enriched fed

fed

0 30 60 90 120 150 180 210 240 270 3000

5000

10000

15000

time (min)

solu

bilit

y (µ

M)

Solubility indomethacin

fasted

fat-enriched fed

fed

0 30 60 90 1200

5000

10000

15000

S1S2S3S4S5

time (min)

solu

bilit

y (µ

M)

0 30 60 90 120 150 180 210 240 270 3000

5000

10000

15000

time (min)

solu

bilit

y (µ

M)

Indomethacin: acid, pKa = 4.6, logP = 3.4

Correlations - pH

• Indomethacin (acid, pKa = 4.6, logP = 3.4)

0 2 4 6 80

1

2

3

4

5

fastedfedenriched

pH

log

(sol

ubili

ty) (

µM)

pKa

R² = 0.86

Correlations – BS, PL

• Danazol (neutral, logP = 4.2)

0 2 4 6 8 100

100

200

300

400

phospholipids (mM)

solu

bilit

y (µ

M)

0 10 20 30 400

100

200

300

400

fastedfedenriched

bile salts (mM)

solu

bilit

y (µ

M)

Correlations – LP

• Diazepam (basic, pKa = 3.3, logP = 2.9)

0 5 10 15 200

2000

4000

6000

8000

fastedfedenriched

lipolytic products (mg/ml)

solu

bilit

y (µ

M)

Biorelevant Conditions

• in-vitro surrogate medium

Composition Fassif Updated Fassif FessifNa Taurocholate (mM) 3 3 15Lecithine (mM) 0.75 0.2 3.75pH 6.5 6.5 5

Maleic Acid (mM) / 19.12 /

Sodium Hydroxide (mM) 8.7 34.8 101

Sodium Chloride (mM) 105.7 68.62 203

Osmolality (mosmol/kg) 270 180 ± 10 670

Intestinal drug solubility

solubility of 17 model drugs withdifferent physicochemical characteristics were investigated:

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

ritonavirprednisolone

glipizide

furosemide

cinnarizine

sulfasalazine

carbamazepine

danazol

quinidine

diazepam

indomethacin

loviride

glibenclamide

fenofibrate

nifedipine

ketoconazole

hydrochlorothiazide

logP

in: - HIF- SIF- d-α-tocopheryl polyethyleneglycol 1000 succinate (TPGS)in phosphate buffer

Mean solubility in fasted HIF versus FaSSIF

y = 5,4x0,79

R2 = 0,91

1

10

100

1000

10000

1 10 100 1000 10000

solu

bilty

in fa

sted

HIF

(µM

)

solubility in FaSSIFc (µM)

Fold error between solubility in FaSSIF, corrected solubility in FaSSIF and solubility in fed HIF.

Mean solubility in fed HIF versus FeSSIF

y = 4,3x0,86

R2 = 0,86

1

10

100

1000

10000

1 10 100 1000 10000

solu

bilit

y in

fed

HIF

(µM

)

solubility in FeSSIFc (µM)

Fold error between solubility in FeSSIF, corrected solubility in FeSSIFc and solubility in fed HIF.

y = 5,2x0,79

R2 = 0,84

1

10

100

1000

10000

1 10 100 1000 10000

solubility in 0,1% TPGS (µM)

solu

bilit

y in

fast

ed H

IF (µ

M)

y = 0,098x1,20

R2 = 0,84

1

10

100

1000

10000

1 10 100 1000 10000

solubility in 2% TPGS (µM)so

lubi

lity

in fe

d H

IF (µ

M)

Overview

• Intestinal drug behavior

Solubility

Supersaturation

Beyond solubility: supersaturation

Supersaturation refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances.

Concept of supersaturation

Con

cent

ratio

n

Time

Equilibrium solubility

Supersaturation zone

PH-Shift method

• Only useful for basic compounds (80%)

Stomach Low pH

GI Tract

Good Solubilitythrough ionization

+H3N

Poor solubilitydue to neutralization

NH2

Similar results compared to solvent shift method for itraconazole

Stomach Low pH

Wat

erba

th @

37°C

Test Medium

Super-saturated

Concentrated drug solution

0 30 60 90 1200

5

10

15

20

25

Time (min)

Degr

ee o

f su

pers

atur

atio

n (D

S)

medium test in solubilityt

tCDS =

Supersaturation Assay

5 Poorly soluble model drugs

Initial DS of 20

Itraconazole Supersaturation in FaSSIF

Supersaturation profile of Itraconazole

0,02,04,06,08,0

10,012,014,016,018,020,0

0 50 100 150 200 250 300Time (min)

Deg

ree

of s

uper

satu

ratio

n Fassif

Itraconazole Supersaturation in FeSSIF

Supersaturation profile of Itraconazole

0,0

5,0

10,0

15,0

20,0

25,0

0 50 100 150 200 250 300Time (min)

Deg

ree

of s

uper

satu

ratio

n

FessifFassif

Human intestinal Fluids?

What about supersaturation in human intestinal fluids ?

Itraconazole supersaturation in Fasted State Human Intestinal Fluids

Fasted HIF V1

0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

0 20 40 60 80 100 120 140

Time (min)

Deg

ree

of S

uper

satu

ratio

n

Itraconazole supersaturation in Fed State Human Intestinal Fluids

Fed HIF V3

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

0 20 40 60 80 100 120

time (min)

Deg

ree

of s

uper

satu

ratio

n

0 20 40 60 80 100 1200

2

4

6

8

10

12

14

16

18

20

22

A

B

C

Time (min)

Degr

ee o

f sup

ersa

tura

tion

factoration Supersatur 2h-0 ABA+

=

DS 1 (solubility)

Impact of medium on precipitation

Etravirine Ritonavir Loviride Danazol Fenofibrate0

1

2

3

4

5

6

7

8

9

10

11

12 FaHIF

Supe

rsat

urat

ion

Fact

or0-

2h

Increasing solubilityBevernage et al, 2010, J Pha Sci 99:4525

Impact of medium on precipitation

Etravirine Ritonavir Loviride Danazol Fenofibrate0

1

2

3

4

5

6

7

8

9

10

11

12 FaHIF FeHIF

Supe

rsat

urat

ion

Fact

or0-

2h

Bevernage et al, 2010, J Pha Sci 99:4525

Impact of medium on precipitation

Etravirine Ritonavir Loviride Danazol Fenofibrate0

1

2

3

4

5

6

7

8

9

10

11

12 FaHIFFaSSIF

FeHIFFeSSIF

Supe

rsat

urat

ion

Fact

or0-

2h

Bevernage et al, 2010, J Pha Sci 99:4525

Impact of medium on precipitation

Etravirine Ritonavir Loviride Danazol Fenofibrate0

1

2

3

4

5

6

7

8

9

10

11

12 FaHIFFaSSIF

FeHIFFeSSIF

Buffer

Supe

rsat

urat

ion

Fact

or0-

2h

Bevernage et al, 2010, J Pha Sci 99:4525

Impact of medium on precipitation

Influence solubility on supersaturation

f

0

5

10

15

20

25

0 50 100 150 200 250 300Time (min)

Deg

ree

of s

uper

satu

ratio

n

ItraconazoleEtravirineLoviride

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

8,00

9,00

10,00

1

ItraconazoleEtravirineLoviride

Absorption assessment: Caco-2

OMS formulation (1)

crystalline itraconazole (2)

(1)

(2)

In vivo exposure (rats)

Itraconazole

0 4 8 12 16 20 240

400

800

Time (hrs)

Plas

ma

conc

entr

atio

n (n

M)

OH-itraconazole

0 4 8 12 16 20 240

400

800

1200

Time (hrs)Pl

asm

a co

ncen

trat

ion

(nM

) Crystalline ITZITZ:SBA-15 1:4Sporanox

Precipitation inhibition in human gastric fluid: excipient effects

Con

cent

ratio

n

Time

solubility

+ excipient

HPMC E5

Eudragit® E-PO

PVP K25

Effect of HPMC on ITZ precipitation in FaSSIF (pH 6.5)

3 µg/ml

0 60 120 180 2400

1

2

3 FaSSIFFaSSIF + 0.05% HPMC

Time (min)

Con

c (µ

g/m

l)

In vivo exposureEffect of HPMC

Itraconazole

0 4 8 12 16 20 240

400

800

Time (hrs)

Plas

ma

conc

entr

atio

n (n

M)

OH-itraconazole

0 4 8 12 16 20 240

400

800

1200

Time (hrs)

Plas

ma

conc

entr

atio

n (n

M) Crystalline

ITZ:SBA-15 1:4SporanoxITZ:SBA-15:HPMC 1:4:1.5ITZ:SBA-15:HPMC 1:4:6

Con

cent

ratio

n

Time

Intestine

Con

cent

ratio

n

Time

Plasma

solubility

Solubility-limited absorptionJ = P ⋅ C

Con

cent

ratio

n

Time

Intestine

Con

cent

ratio

n

Time

Plasma

solubility

Supersaturation J = P ⋅ C

Con

cent

ratio

n

Time

Intestine

Con

cent

ratio

n

Time

Plasma

solubility

Supersaturation + precipitationJ = P ⋅ C

Con

cent

ratio

n

Time

Intestine

Con

cent

ratio

n

Time

Plasma

solubility

Supersaturation + precipitation:low permeability J = P ⋅ C

Con

cent

ratio

n

Time

Intestine

Con

cent

ratio

n

Time

Plasma

solubility

J = P ⋅ CSupersaturation + precipitation:high permeability

06/06/2012 54

Solu

bilit

y(µ

M)

Solubility profiling of HIV-PI

55

Solubility profiling of HIV-PI

56

Solubility profiling of HIV-PI

Prediction of food-effects

57

Solubility profiling of HIV-PI

Conclusions

• High intra/inter subject variability

• FaSSIF & FeSSIF: adequate solvent systems for:• Solubility estimation• Supersaturation evaluation• Prediction of food effects

Acknowledgements

• Laboratory for Pharmacotechnology & Biopharmacy, KU Leuven

Jan BevernageMichiel Van SpeybroeckNico HolmstockRandy MellaertsJoachim Brouwers

• Center for Gastroenterology, University Hospitals LeuvenRita Vos, Jan Tack

• FundingResearch Foundation Flanders (‘FWO’); Agency for Innovation by

Science and Technology (‘IWT’); KU Leuven

Overview

• Intestinal drug behavior

Solubility

Supersaturation

• Gastric drug behavior:

Case study posaconazole

Posaconazole in the lab

• XLogP = 4.6• aqueous solubilty < 1 µg/ml• high permeability• BCS II• weak base (pKa 3.6 and 4.6)

Posaconazole: influence of gastric conditions

Posaconazole pharmacokinetics and gastrointestinal behavior

– crossover study (5 healthy volunteers)

– oral administration of a single dose (400 mg) of Noxafil®

– posaconazole concentration-time assessment

• plasma

• gastric fluid

• intestinal fluid

– 4 different conditions

• water

• PPI / water

• PPI / cola

• cola

Posaconazole & PPI

Stomach

0 30 60 90 120 150 180 210 240 270 3000

2

4

6

8

Water PPI - Water

Time (min)

pH

0 30 60 90 120 150 180 210 240 270 3000

100

200

300

400

500

Time (min)

Posa

cona

zole

(µM

)

Posaconazole & PPI

Plasma

0 6 12 18 24 30 36 42 480.00

0.05

0.10

0.15

0.20 WaterPPI - Water

Time (h)

Posa

cona

zole

(µM

)

Posaconazole & PPI & Cola

Stomach

0 30 60 90 120 150 180 210 240 270 3000

2

4

6

8

Water PPI - Water PPI - Cola

Time (min)

pH

0 30 60 90 120 150 180 210 240 270 3000

100

200

300

400

500

Time (min)

Posa

cona

zole

(µM

)

Posaconazole & PPI & Cola

Plasma

0 6 12 18 24 30 36 42 480.00

0.05

0.10

0.15

0.20 WaterPPI - WaterPPI - Cola

Time (h)

Posa

cona

zole

(µM

)

Posaconazole & Cola

Plasma

0 6 12 18 24 30 36 42 480.0

0.1

0.2

0.3

0.4 WaterCola

Time (h)

Posa

cona

zole

(µM

)

Posaconazole & Cola

Stomach

0 30 60 90 120 150 180 210 240 270 3000

2

4

6

8

Water Cola

Time (min)

pH

0 30 60 90 120 150 180 210 240 270 3000

200

400

600

800

1000

Time (min)

Posa

cona

zole

(µM

)

Posaconazole & Cola: effects of cola

Solubilization

0 30 60 90 120 150 180 210 240 270 3000

200

400

600

800

1000WaterCola

Time (min)

Posa

cona

zole

(µM

)

pH 1.2 pH 2.5 pH 6.50

20

40

60800

1600

2400 ColaSGFFaSSIF

Posa

cona

zole

sol

ubili

ty (µ

M)

Increased gastric dissolution time

normal gastric pH: dissolution-limited absorption

Summary: gastric conditions & fasted state posaconazole absorption

• Gastric dissolution affects posaconazole absorption

• Clinically: coadminister posaconazole with cola– with PPI: partially restored fasted state absorption– without PPI: improved fasted state absorption

• Posaconazole formulation improvements are desirable– dissolution rate / solubility

• Mechanistically: effect of cola– pH-dependent increase in solubility (in case of abnormal gastric pH

levels)– pH-independent increase in solubility– increased gastric dissolution time

y = 64,4x0,55

R2 = 0,75

1

10

100

1000

10000

0,1 1 10 100 1000 10000

solubility in blank FeSSIF (µM)so

lubi

lity

in fe

d H

IF (µ

M)

y = 34,3x0,56

R2 = 0,81

1

10

100

1000

10000

0,1 1 10 100 1000 10000

solubility in blank FaSSIF (µM)

solu

bilit

y in

fast

ed H

IF (µ

M)

Conclusions

• High intra/inter subject variability

• FaSSIF & FeSSIF: adequate solvent systems for:• Solubility estimation• Supersaturation evaluation

• Conditioning environment of the stomach

Preparation room Waiting room