proprietary and confidential © astrazeneca 2009 for internal use only issues associated with the...

Proprietary and Confidential © AstraZeneca 2009FOR INTERNAL USE ONLY

Issues Associated with the Manufacture of Large Scale

Crystalline Nanosuspensions


• Small volume crystalline drug nanosuspensions manufactured at AP using Fritsch P7 Planetary Micromill with zirconia milling pots & zirconia beads.

• Fritsch P7 Mill limited to relatively small volume manufacture.

~ 32ml

• Dynomill was acquired to manufacture large volume crystalline nanosuspensions –used stainless steel mill chamber and high density/highly cross-linked polystyrene milling beads (zirconia chambers available but very expensive)

• Can process litres of suspension

• Suppliers of polystyrene milling beads DOW (had an exclusivity agreement with ELAN). AZ obtained beads from NORSTONE.

• Mid 2010 NORSTONE signed exclusivity agreement with “?” – would not supply beads to AZ in future – alternative bead required.

History

Manufacture of crystalline nanosuspensions at Alderley Park


History

• A feasibility study was carried out at Sodertalje to identify an alternative.

• Trials used glass beads as it was perceived there might be issues with zirconia (heavy metal) for clinical manufactures.

• Sodertalje investigated soda lime & borosilicate beads of different sizes from suppliers such as:- Sigmund-Lindner, Sigma, Mo-Sci, Retsch-VWR & Christian Berner.


Sigmund-Lindner

Sigma

Mo-Sci

Retsch

Glass Beads Before and After Milling Run in Dynomill

Christian Berner


Manuf./Supplier Type1 Size [µm]

pHbef/aft

Milling efficiency

Milling observations

Abrasion(SEM)

Metals[AU] (EDS)

Residuals [weight%]

AZ PS 400-600 6.0/6.1

Sigmund Lindner

SL 250-500 6.6/11.5

Sigmund Lindner

SL 400-600 4.4/11.0

Sigmund Lindner

BS 500-750 4.3/10.3

Sigma SL 150-212 4.6/10.8

Sigma SL 425-600 5.5/10.4

MO-SCI BS 180-212 5.4/7.6

MO-SCI SL 400-600 4.7/11.5

Retsch/VWR SL 250-500 10.42/11.5

Retsch/VWR SL 500-750 5.7/11.5

Christian Berner

SL 300-700 4.2/11.2

Alternative Beads Selected Based on Performance versus Polystyrene Beads

Much worse than control

Better than or equal to controlSlightly worse than control


Crystalline Drug Nanosuspension Manufacture• Initially a nanosuspension was prepared by bead milling (using Fritsch P7 Planetary Mill & zirconia milling media) as limited exposure had been observed with a microsuspension formulation.

M.E. Commonly use 3 prototype drug formulations dependant on the physical properties of the drug

• Initial nanosuspension was manufactured at 200mg/ml drug load in vehicle PVP/Aerosol OT and had mean particle size <200nm.


Structures of Stabilizing Surfactants

Dioctyl sodium sulfosuccinate (Aerosol OT ex Cytec) (anionic)

Polyvinylpyrrolidone (ex BASF) (non-ionic)

DPPE-PEG2000 (Dipalmitoylphosphatidylethanolamine - poly(ethylene glycol) 2000 (ex Genzyme) (anionic)

Hydroxypropylmethylcellulose (ex Dow) (non-ionic)

Polyoxyethylene (20) sorbitan monooleate (Tween 80) (non-ionic)

http://en.wikipedia.org/wiki/File:Dioctyl_sodium_sulfosuccinate.png


Crystalline Drug Nanosuspension Manufacture

• MTD and DRF studies required the manufacture of several litres of nanosuspension – Dynomill manufacture.• Bead milled drug in Dynomill at 200mg/ml using vehicle

PVP/Aot with MO-SCI soda-lime glass beads



Measured Levels in suspension: Limits by EMEA:

Fe: 42 ppm 1300 ppm

Ni: 7 ppm 25 ppm

Cr: 10 ppm 25 ppm

Knew from feasibility study - Soda-lime glass beads would cause suspension pH to rise > pH9, and also metal and colloidal glass contamination.

Measured pH of suspension was ~pH9.1

Analysis showed the metal levels were below acceptable limits.



pH Adjustment: Attempted to manually adjust pH to pH6.9 by addition of 1M HCl – but reduced pH to ~pH2

which resulted in coagulation of the nanosuspension

A nano suspension at pH 6.9 (from Fritsch mill) was manually pH adjusted to pH 9.1 and

then successfully re- adjusted to pH 6.9 using 0.1 M acetic acid (weak acid).

This nanosuspension remained as free flowing particles no visible evidence of

aggregation

However after addition of HCl adjusting pH to ~ 2, the nanosuspension coagulated.

What would happen when dosed orally?Nanosuspension also coagulated when diluted in Simulated Gastric Fluid



Preparation of nanosuspension at 200mg/ml in PVP/Aot in Acetate Buffer at pH4.6 – was successful

d10 74nmD50 168nmd90 503nm


Preparation of nanosuspension in DPPE-PEG2000 200mg/ml A 200mg/ml suspension in 4% DPPE-PEG2000 milled on the

Fritsch mill produced a suspension with a similar overall size profile to that obtained with PVP/Aot:

d50= 144nm d90= 644nm

When diluted into SGF the DPPE-PEG2000 nanosuspension DID NOT COAGULATE but remained as free-flowing individual particles.

However problems as to the suitability of this vehicle due to possibility of anaphylactic shock in dogs (due to peroxide content) also doubts about whether DPPE-PEG2000 can be taken forward into FTiM studies.


d10 69nm d50 144nm d90 644nm

Formulation was therefore deemed not suitable for use in the dog tox study and study postponed.

Mouse study went ahead as only required small volumes which could be manufactured using the Fritsch mill

Dog PK study was set up to assess whether there was any advantage in dosing a nanosuspension compared to a microsuspension

Although there was variability in exposure, the results indicated the dog MTD could commence with a microsuspension,whilst further work progressed on the nanosuspension formulation

However tox observed with microsuspension.


Flocculation/Coagulation Testing of Drug Microsuspensions in PVP/Aot

Microsuspension (200mg/ml) in PVP/Aot Diluted 1:3 in SGF adjusted to pH4.5 Diluted 1:3 in SGF (pH1.2)

Carried out Flocculation/Coagulation testing of microsuspension formulations

Diluted microsuspension manufactured in PVP/Aot and manufactured in HPMC/Tween80in SGF and in SGF adjusted to pH4.5 (mimic mouse)

√ = no coagulation X = coagulation

PVP/Aot is not a good stabiliser system for this compound

Vehicle Dilute in SGF Dilute in SGF/pH4.5

HPMC/Tween80 √ √

PVP/Aot X √


SUMMARYNanosuspension manufactures using SL glass beads will result in high pH suspensions unless buffered

PVP/Aot

The PVP/Aot vehicle makes suspensions at 200mg/ml in the Fritsch Mill using zirconia media that are chemically and

physically stable.

The suspensions in PVP/Aot coagulate spontaneously when diluted into SGF (1:3 dilution) or when pH reduced to ~pH2

A nanosuspension can be prepared at 200mg/ml in PVP/Aot/acetate buffer(pH4.6) – but the suspension coagulated when

diluted into SGF or pH reduced to ~2

DPPE-PEG2000

A nanosuspension could be prepared at 200mg/ml drug load in 4% DPPE-PEG2000 which does not coagulate when diluted in SGF

Issues found with milling with glass beads – pH rise, some glass and metal contamination (albeit below recommended limits).

Could be an issue for compounds unstable at high pH – but it is possible to manufacture in vehicle/buffer

Accidentally found out that the nanosuspension in PVP/Aot coagulated at gastric pH.

Also found out microsuspension in PVP/Aot coagulated at gastric pH indicating that PVP/Aot not a good stabilizer for this compound


Recommendations

M.E. do not routinely carry out flocculation/coagulation testing on suspensions – maybe we should?

If it had not accidentally been found that the nanosuspension coagulated at gastric pH the nanosuspension would have been dosed, probably would have coagulated in the stomach, producing low exposures and variable results

Future reference:- Important to choose optimum stabiliser system for nanosuspension manufacture

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