High-throughput Crystallization: Processes and Applications Sherry L. Morissette Diversity Amidst Similarity A Multi-disciplinary Approach to Polymorphs,

High-throughput Crystallization: Processes and Applications

Sherry L. Morissette

Diversity Amidst Similarity

A Multi-disciplinary Approach to

Polymorphs, Solvates and Phase Relationships 35th Crystallography Course, Erice, Italy

June 19, 2004

The MissionThe Mission

CompoundCompound Discovery Discovery

PreclinicalPreclinicalDevelopmentDevelopment

Clinical Clinical Development Development

RegulatoryRegulatoryApprovalApproval

Marketing Marketing and Salesand Sales

The QuestionsThe Questions

1) Why is solid form important in pharmaceutical development?

2) How is it typically investigated?

3) What do high-throughput (HT) crystallization techniques have to offer?

4) How does the HT process work?

5) Does it really work?

Why is Solid Form Important?Why is Solid Form Important?

diamond graphite fullerenes nanotubes

Solid Forms of Carbon

The crystal structure of a compound impacts the physicochemical and performance properties, as well as the value/utility of a material

Crystal Structure

Physicochemical/Performance

Properties $Value/Utility


Thermal Mechanical Electrical Optical

Crystal Structure

Solubility Dissolution rate Hygroscopicity Stability Flowability Compaction

Performance Properties



Properties $Value/Utility


Crystal Structure $Value/Utility

Enable a product Reduce dose Improve onset of action Better storage conditions Patent protection


Properties


What are Pharmaceutical Solids?What are Pharmaceutical Solids?

Active pharmaceutical ingredients (API) can exist in a variety of solid forms, including:

Polymorphs Solvates Hydrates

Salts Co-crystals Amorphous forms

Solubility

Bioavailability

Stability

Processability

The Challenge: Solid Form SelectionThe Challenge: Solid Form Selection

The solid form selected for development must exhibit an appropriate balance of important physicochemical properties

Crystalline solid (preferred) Adequate solubility and/or dissolution behavior Physically stable (processing & storage) Non-hygroscopic (or minimally hygroscopic) Chemically stable

Crystallization – So Many Variables!Crystallization – So Many Variables!

Composition Type Process Variables*

Polymorphs & Solvates

Salts & Co-crystals

Thermal Anti-solvent Evaporation Slurry conversion

Other variables

Solvent/solvent combinations

Degree of supersaturation

Additive type Additive con-

centration

Counter ion type Acid/base ratio Solvent/solvent

combinations Degree of super-

saturation Additive type

and concent. pH (aqueous) Ionic strength

Heating rate Cooling rate Maximum

temperature Incubation

temperature(s) Incubation time

Anti-solvent type Rate of anti-

solvent addition Temperature of

anti-solvent addition

Time of anti-solvent addition

Rate of evaporation

Evaporation time

Carrier gas Surface-

volume ratio

Solvent type Incubation

temperature Incubation time Thermal

cycling and gradients

Mixing rate Impeller design Crystallization

vessel design (including capillaries, etc.)

The form outcome of a crystallization experiment is influenced by both composition and process parameters

Identify and characterize the solid forms of an API Evaluate performance properties of different forms

Staged approach often used Determine stability relationships between forms (identify stable form) Investigate processing effects on form

Crystallization Drying Granulation/Milling Storage

Select optimal form for development

Satisfy regulatory requirements

Generate & secure intellectual property

Solid Form Screening: GoalsSolid Form Screening: Goals

How is solid form of an API typically investigated?How is solid form of an API typically investigated?

Set-up exp. Pray for crystals Look for crystals

Change dieties!

Guess new conditions

Form Discovery ApproachesForm Discovery Approaches

Thermal microscopy

Slurry conversion

Recrystallization

Exploration of a few salts

Traditional Major drawback:

Slow, manual process

Manual, bench - top process Average number of experiments ~ 10 -20 Turnaround time ~ 1-2 months Compound available ~ 1g Limited exploration of experimental

space

[API]

Solvent

Process


Thermal microscopy

Slurry conversion

Recrystallization


Polymorph prediction Progress has been made but still challenging

Salt structure prediction computationally intractable

More recent


Thermal microscopy

Slurry conversion

Recrystallization


Polymorph prediction Progress made but challenging

Salt structure prediction computationally intractable

High throughput (HT) crystallization

Now

Miniaturization of crystallization exp. Large numbers of experiments Reduced compound use Automation of tedious operations Multiple processing options (in parallel or serially)

Execution and analysis bottlenecks solved Informatics software

Improved experimental design Sample tracking Mining of resulting data: detection of trends, learning

Streamlined end-to-end process

Benefits of HT CrystallizationBenefits of HT Crystallization

HT

High-throughput offers the ability to explore solid form space more comprehensively than ever before possible

HT Process Flow: CrystalMax® HT Process Flow: CrystalMax®

Design Execution Analysis

Data mining & modeling

Secondary solids

characterization Functional characterization

Design of experiment

Streamlined end-to-end process

Sample preparation Solids

generationSolids

detection Sample isolation Primary solids

analysis Initial informatics classification

Generic Functional Process FlowGeneric Functional Process Flow

PREPAREMATERIALS

REMOVESOLVENT

ADDCOUNTER-ION

SEALVIAL

HEAT/COOL/STIR CONTENTS

ADDADDITIVE/

ANTISOLVENT

EVAPORATELIQUIDS

ANALYZE MATERIAL

RECORDSINSTRUCTIONS

SOLIDS

SUPERNATANT

(FOR FURTHERPROCESSING)

REMAININGSAMPLE

SAMPLES FORINCUBATION

CRYSTALS ORAMORPHOUS

SEALEDSAMPLES

COLLECT MATERIAL

ADDSOLVENTS

PREPAREINFORMATION

(DoE)DB

DISPENSEAPI

RE-ARRAY

CRYSTAL CHECK

Thermal Recrystallization Process Thermal Recrystallization Process

PREPAREMATERIALS

REMOVESOLVENT

ADDCOUNTER-ION

SEALVIAL

HEAT/COOL/STIR CONTENTS

ADDADDITIVE/

ANTISOLVENT

EVAPORATELIQUIDS

ANALYZE MATERIAL

RECORDSINSTRUCTIONS

SOLIDS

SUPERNATANT

(FOR FURTHERPROCESSING)

REMAININGSAMPLE

SAMPLES FORINCUBATION

CRYSTALS ORAMORPHOUS

SEALEDSAMPLES

COLLECT MATERIAL

ADDSOLVENTS

PREPAREINFORMATION

(DoE)DB

CRYSTAL CHECK

DISPENSEAPI

RE-ARRAY

Design of Experiment (DoE)Design of Experiment (DoE)

DoE goals: Design a diverse experiment covering a large multi-factorial parameter space, with the goal of determining which experimental factors affect the desired outcome

In practice, it is necessary to place constraints on the experimental space

Hardware limitations Minimum and maximum dispense volumes or masses Accessible temperature ranges

Chemical compatibility Reactivity of components Miscibility Tolerablility/toxicology limits of components (if appropriate)

AnalysisExecutionDesign

AnalysisExecutionDesign

Each as-received compound is first characterized to determine solid form & properties

Software tools are used to specify the components of each individual experiment in the large array of experiments

Number of experiments Amount of API per well (levels of supersaturation) Solvent composition (unary, binary, ternary, etc.) Additive type and amount (counter ion, anti-solvent, etc.) Processing conditions (recrystallization, evaporation, etc.)

The specific design of a given experiment depends on the type of experiment being conducted

Design of Experiment (DoE)Design of Experiment (DoE)

AnalysisExecution

DoE Tools: Diversity GeneratorDoE Tools: Diversity Generator

Design

Diversity generator: software tool that uses a set of pertinent chemical properties selected by the experimentalist to define the experimental space (e.g., chemical mixture space)

Experimental points are then evenly spaced over the chosen property space

AnalysisExecution

DoE Tools: Solubility EstimatorDoE Tools: Solubility Estimator

Design

Solubility estimator: software is used to estimate the solubility of the API in the given solvent/additive mixture at a specified temperature

Upper and lower limits on API concentration established for temperature range of experiment

Experiments normalized with respect to driving force for crystallization

Possible to gain insight into the role of solvents and/or supersaturation on the resulting solid form

With DOE tools, experiments may be designed to effectively and simultaneously explore diverse composition and process spaces

HT Crystallization ProcessHT Crystallization Process

Initial informatics classification

Design AnalysisExecution

Sample preparation Solids

generation Solids detection Sample

isolation Primary solids analysis



Sample preparation

Each component is dispensed as specified by the DoE into an individually addressable vial

Each vial is immediately sealed to ensure composition control

Deposit API(0.2 – 2mg)

Remove carrier solvent

Dispense solvent(s) &

additives

Immediately seal each vial

Transfer to incubation

station

DoE input from database



Solids generation

Solids can be generated by a number of methods Thermal cooling (recrystallization) Anti-solvent addition Evaporative crystallization Melt crystallization Flash/quench cooling Template-directed crystallization

Multiple process modes should be used to ensure generation of

maximal solid form diversity



Solids detection

Machine vision system used to intermittently inspect vials for solids formation

State changes in the crystallization vessels are recorded in database, signaling a particular vessel or set of vessels is ready for isolation & analysis

Solids detection process is automated, rapid and non-destructive

Optical inspection

Birefringence detection



Sample isolation

Vials containing solids are re-arrayed; remaining samples are returned to the incubation station for further incubation or processing

Re-arrayed samples are optionally quenched by aspiration of the solution phase and dried using flowing nitrogen



Primary solids analysis

HT- Raman Spectroscopy HT- pXRD



Primary solids analysisIn-situ Raman Spectroscopy

Rapid, in-situ measurement > 1000 samples per day

Highly selective to crystal structure Meas. independent of sample size Orientation effects minimized by

sample rotation



Primary solids analysis

HT-pXRD carried out on arrays of samples

Aliquots of samples re-arrayed to pXRD format

Sampling method minimizes preferred orientation

Acquisitions times are short (typically ~ 1- 3 mins) Approximately 300-400 samples per day


Initial informatics

classification


Manual comparison of data impractical

Similar

Dissimilar


Raman/pXRD acquisition Correction (filtering) Peak picking Comparison Classification

Proprietary software used to compare and cluster spectra/diffractograms

Initial informatics

classification



Initial informatics

classification

Design Analysis

Raman and pXRD, as well as other data types, can be co-binned, allowing cross-referencing of multiple data types

Software used to aid selection of representatives from each cluster of like samples on which to perform secondary characterization

Execution



Secondary solids analysis

DSC, TGA, optical microscopy, HPLC, KF

single crystal structure (if possible)

Melting point, crystal habit, stoichiometry

Dissolution, DVS, slurry conversion

Solubility, dissolution, hygroscopicity, stoich.,

phys./chem. stability

Functional analyses

Scale-up required

Descriptor-based analysis

Mapping of exp. conditions to crystal form produced

Data mining & modeling

CrystalMax® Process OverviewCrystalMax® Process Overview

Fully automated & integrated Flexible operation: process mode(s), amount material, etc. Parallel experimentation: capable > 10,000 crystallization

experiments / week More comprehensive examination of form space

Selection of materials for crystallization vessels & seals Compatible with solvents, temperature Must allow inspection of and sampling from vessels; avoid wetted seals Low cost, disposables

System flexibility Amount of material required (for individual experimental well & total) Types of experimental designs How and when processes are applied Individually addressable samples (control of isolation time) Selection of primary and secondary analysis methods to be used

Sample & process tracking Unique identifiers for individual samples All steps tracked and recorded to DB Tracking of off-line experimental work

Sample analysis Primary classification must be rapid and selective Multiple solid-state characterization methods preferred

Data handling Analyses tools should allow evaluation of partial data sets Data mining & models feed DoE

Technology Design ConsiderationsTechnology Design Considerations

CrystalMax® Application ExamplesCrystalMax® Application Examples

Sertraline HCl: Highly polymorphic

Sertraline: Salt selection

Ritonavir: Latent polymorphism

Polymorph/solvate screening

Crystallization of amorphous compounds

Salt selection

Co-Crystal discovery

Case Study: Sertraline HClCase Study: Sertraline HCl

Active ingredient in Zoloft®

Multiple crystal forms disclosed Highly polymorphic 17 discrete

forms reported Multiple hydrate (6) and solvate (4)

forms known

Most stable polymorph of the HCl salt is in the marketed product

Cl

Cl

NHCH3 HCl

GOALS Assess solid-form diversity of the HCl salt

Investigate alternative salt forms & propensity for polymorphism

HT Crystallization Sertraline HClHT Crystallization Sertraline HCl

Experimental Design ~ 3,100 experiments 2 supersaturation levels

1.0 – 2.5 mg compound/well

24 diverse solvents Unary, binary and ternary mixtures

Varying process methods Thermal recrystallization at 2

incubation temperatures (5 and 25°C)

Slurry conversion using solvent array

Melt crystallization using varying temperature profiles

Varying desolvation methodologies

Results 10 distinct forms identified

from solvent-based recrystallization

4 additional forms were generated from desolvation & melt crystallizations

2 novel solvates identified Acetic acid (1:1) Ethyl acetate (2:1)

8 reported forms shown to be unstable (transient) or occur only in mixtures

Crystal Forms Identified in ScreenCrystal Forms Identified in Screen

Found by Follow-up to HT-Screen

Found by HT-Screen Mixtures & Transient Species

Multiple processing methods needed for more comprehensive form discovery

HT Crystallization Sertraline HCl: SummaryHT Crystallization Sertraline HCl: Summary

All but 1 known non-transient form of the HCl salt were found in ~ 6 weeks

2 novel forms of the HCl salt were discovered, one of which is pharmaceutically acceptable

Almarsson et al. Crystal Growth & Design. Published on the web 9/10/2003.

Sertraline HCl Form I. 20x

Varied process conditions and follow-on experimentation critical to understanding crystal form diversity

Several duplications and errors in existing patent disclosures were found

Acetic acid solvate of Sertraline HCl

HT Salt Selection: SertralineHT Salt Selection: Sertraline

Experimental Design ~ 3,600 experiments Variety of

pharmaceutically acceptable counter ions Mono-, di- and tri-acidic

Range of stoichiometries Monoacidic: 1.05 equivalents Polyprotic: 0.55 and 1.05

Focused solvent array Thermal process method

Samples were heated to 65 °C for

2 h & cooled at 1 °C/min. to 25 °C

Results

18 crystalline salt forms identified

Multiple modifications of several of the salt forms were identified in this limited screen

Besylate

Partial Results: Sertraline SaltsPartial Results: Sertraline Salts

Fo

rm A

Fo

rm B

PXRD patterns of samples from benzoate clusters

Bromide salt not overtly polymorphic

> 140 discrete samples from different conditions analyzed

Bromide Salt of Sertraline: Crystal StructureBromide Salt of Sertraline: Crystal Structure

Study highlights the value of parallel polymorph and salt selection to elucidate optimal forms

View along the a axis of the single-crystal structure of sertraline HBr

Non centrosymmetric orthorhombic space group: P212121 2-D hydrogen-bonded network Primary motif: H-bonded chains (N-

H···Br) propagating along the b axis Secondary hydrogen bonds (C-H···Cl-C)

complete the two-dimensional network

Four molecules of the salt in the unit cell

18 crystalline salt forms found 7 previously undisclosed crystalline salt forms

3 are not overtly polymorphic

Polymorphic behavior of pharmaceuticals is not readily predictable

even when seemingly minor changes to the composition are made

HT crystallization provides for a more comprehensive understanding of solid form diversity to enable selection of the optimal form for development

Remenar et al. Org. Proc. Res. Dev. in press (2003)

HT Salt Selection Sertraline: SummaryHT Salt Selection Sertraline: Summary

NORVIR®: A ‘Real’ ProblemNORVIR®: A ‘Real’ Problem

Excerpt from new product label: Store soft gelatin capsules in the refrigerator between 36-46°F (2-8°C) until dispensed.

Ritonavir BackgroundRitonavir Background

Case history: ABT-538 discovered Launch of semi-solid capsule/polymorph I Polymorph II appears, <50% solubility Massive effort to ‘recover’ the oral capsule Reformulated softgel capsule launched

1992199619981998 - 19991999

ONH

HN

NH

N

CH3

O

OHO

CH3H3CO

N

SS

NH3C

H3C

Known polymorphs found 2 new forms found in the screen Reproducible methods of making

2000 conditions 32 solvents

Unary, binary and ternary mixtures

Varying super-saturation levels

> 50 solids formed

A: Form I (PXRD)

B: “Form III”

C: Form II (PXRD)

D: “Form IV”

Ritonavir HT ExperimentRitonavir HT ExperimentSimilarity

High

Low

Ritonavir PXRD and Thermal AnalysisRitonavir PXRD and Thermal Analysis

I

II

III

V

IV

mp (oC) Hfus, J/g

122 78.2

125 87.8

78-82 60.3

97 32.0

116 59.6

* Chemburkar et al. Org. Proc. Res. Dev. 4, 413 (2000)

*

*

Formamide solvate

Hydrated

Form V hydrate isolated after slurrying in water All new forms comvert to Form I (initially) when

incubated in water

Summary of Ritonavir Crystal FormsSummary of Ritonavir Crystal Forms

Form III: formamide solvate Form IV: obtained from acetonitrile and acetate solvents Form V: derived from III with moisture exposure

Forms IV and V eventually transform to form I

TransForm 2002 – 6 week effort

Concluding RemarksConcluding Remarks

HT crystallization technologies enable a more comprehensive understanding of the solid forms of a compound

Multiple methods should be employed to make & characterize different solid forms

HT should be coupled with bench-top studies for full characterization & discovery of novel forms

Scientific validation for the approach continues to grow

HT should not be considered a substitute for good science but rather a complement to it

The HT process is automated, not automatic!

AcknowledgementsAcknowledgements

S. Morissette, et al., “High- throughput Crystallization: Polymorphs, Salts, Co-crystals and Solvates of Pharmaceutical Solids,” Adv. Drug Delivery Rev., 56[3] 235-418 (2004).

TransForm Colleagues

Colin GardnerÖrn AlmarssonJulius RemenarMatt PetersonMike McPheeStephen SoukaseneHector Guzman Chris McNultyCameron OlbertTony LemmoSteve Ellis

Scientific Advisors

Michael Cima Joel BernsteinRoger DaveyLeslie LeiserowitzMoungi Bawendi

“…the number of forms known for a given compound is proportional to the time and energy spent in research on that compound.” (McCrone, 1963)

How many experiments do you have to do?

Sertraline HCl Acetic Acid Solvate Sertraline HCl Acetic Acid Solvate

a=9.1599Åb=8.8275Å =93.196ºc=12.0714Å

Monoclinic: P21

Acetic acid propagates a 1-D hydrogen bonded network with sertraline HCl between the carboxylic acid group and protonated secondary amine of the drug via the chloride ions

At room temperature, solvate converts to form V on desolvation at %RH > 35%

Thermal microscopy Slurry conversion Recrystallization Exploration of a few salts

Typical methodologies Manual, bench-top process Average number of experiments ~ 10 -20 Turnaround time ~ 1-2 months Compound available ~ 1g Limited exploration of experimental space

[API]

Solvent

Process

Traditional Form ScreeningTraditional Form Screening

Polymorph Prediction Progress made but still a challenge Salt structure prediction currently computationally

intractable

Alternative approach needed to address shortcomings of existing solid form screening methods

HT Analysis StrategyHT Analysis Strategy

I

II

III

IMPRACTICAL

IMPRACTICAL

Documents

High-throughput Crystallization: Processes and Applications Sherry L. Morissette Diversity Amidst Similarity A Multi-disciplinary Approach to Polymorphs,