Active pharmaceutical ingredients
Presented By
Rutendo Kuwana
Training workshop: Training workshop on regulatory requirements for registration of Artemisinin based combined medicines and
assessment of data submitted to regulatory authorities, February 23-27, 2009, Kampala, Uganda.
Presentation approach
 Discuss aspects of the information that is required for the
API for WHO Prequalification
 Use examples from literature as well as experience from
the WHO PQ Project
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Some definitions
Active Pharmaceutical Ingredient (API)
A substance or compound that is intended to be used in
the manufacture of a pharmaceutical product as a
therapeutically active compound (ingredient)
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Some definitions (2)
Enantiomers
cpds with same molecular formula as substance but differ in spatial
arrangement of atoms and are non-superimpossable mirror images
Polymorphism – occurrence of different crystalline forms of the same
substance
Degradation product – molecule resulting from chemical change in
substance due to e.g. light, temperature, pH, water, reaction with
excipient, immediate container/closure
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Some definitions (3)
Impurity – any component of the medicinal product which is not the
chemical entity defined as the active substance or an excipient of
the product
Identified Impurity – an impurity for which structural characterisation
has been achieved
Unidentified degradation product – an impurity defined only by
qualitative properties e.g. Rt
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Available information on API
Applicants should collect and analyse available information
of the API in a systematic approach. This approach
 Leads to a sound scientific understanding of the API, with
respect to properties, stability, specifications, etc.
 Assists in API manufacture and DMF compilation
 Leads to the appropriate choice of API manufacturer (source)
 Assists in dossier compilation
 Is important for FPP pharmaceutical development
 Leads to reduction of time / cost
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Literature information on API
Standard works / series / books – such as:



(Analytical) Profiles of Drug Substances and Excipients [eds: Florey / Brittain
– 31 volumes]
The Merck Index (for structures, properties)
Pharmaceutical Codex (12th edition) (“old” APIs)
Journals through search facilities such as

International Pharmaceutical Abstracts, Chemical Abstracts, Analytical
Abstracts & internet
Pharmacopoeial monographs (current)
Analysis of structure & stereochemistry
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Information from
literature and structures
 APIs which are organic compounds, have unique
chemical structures & stereochemistry
 These structures, together with the solid/liquid state
conditions, are basically responsible for chemical and
physical properties of the APIs
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Guidelines
 Guideline on Submission of Documentation for Prequalification of Multi-Source
(Generic) Finished Pharmaceutical Products (FPPs) Used in the Treatment of
HIV/AIDS, Malaria and Tuberculosis [GuideGeneric]
 Guidance on Variations to a prequalified Dossier [Variation Guide]
 Guideline on Active Substance Master File Procedure [CPMP/QWP/227/02 Rev1]
– Guideline on Active Pharmaceutical Ingredient Master File (APIMF) Procedure
[Draft]
 Guideline on Summary of Requirements for Active Substances in the Quality Part of
the Dossier [CPMP/QWP/297/97 Rev 1 corr]
 ICH Q3A [R] Impurities Testing Guideline: Impurities in New Drug Substances
[CPMP/ICH/2737/99]
 ICH Q6A Specifications: Test Procedures and Acceptance Criteria for New Drug
Substances and New Drug Products: Chemical Substances [CPMP/ICH/367/96 corr]
 ICH Q2A Validation of Analytical Procedures: Definitions and Terminology
[CPMP/ICH/381/95]
 ICH Q2B Validation of Analytical Procedures: Methodology [CPMP/ICH/281/95]
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Literature support
Literature information used in the dossier should always be
accompanied by
Full traceable reference citations
Photocopies of publication or relevant pages
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties of APIs
Scenarios:
API not described in BP, Ph., JP, Ph.Eur., or USP (non - compendial)
• Considered new
– (?) information on (adverse) drug reaction
• Risk estimation high
• Profound information necessary
API described in BP, Int.Ph., JP, Ph.Eur.,or USP (compendial)
• Considered in use
– Information on (adverse) drug reaction (monitored)
• Risk estimation based on available data
• Information necessary limited to data beyond the monograph
– Essential control by the monograph
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties of API(s)
 APIs not described in BP, PhInt, PhEur or USP
• a) evidence of chemical structure
– spectral data
– Single crystal X-ray structure (sufficient) or
– Spectrometric data (IR, 1H & 13C NMR, MS, etc.): QA certified
copies of the spectra and tabulated data with
• assignments against structure/interpretation of data (narrative)
• b) evidence of chemical structure
– Isomerism
– Stereochemistry
– Discussion of potential isomeric forms
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties of API(s)
 Properties relevant/critical for the performance of the API
• c) potential polymorphic forms
– Influence on physicochemical and physical characteristics (solubility,
hardness, compressibility, density, melting point, etc.) Must be
controlled
• d) particle size distribution
– requirement for low solubility drugs (dissolution, bioequivalence)
• e) additional characteristics
– critical characteristics to be controlled to ensure consistent
performance of the API (e.g. hygroscopicity)
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties: non-compendial APIs
 Proof of structure/stereochemistry correctness
• correlation against API spectral data from peer reviewed literature,
preferable innovator publication (in tabulated form!!). Strongly
recommended
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties of API(s)
 APIs described in BP, PhInt, PhEur or USP
– Evidence of chemical structure
• control of structure by suitable compendial identification tests
– Properties relevant/critical for the performance of the API (not necessarily
covered by the monograph)
• a) potential polymorphic forms
– Influence on physicochemical and physical characteristics (solubility,
hardness, compressibility, density, melting point, etc.) Must be
controlled
• b) particle size distribution
– requirement for low solubility drugs (dissolution, bioequivalence)
• c) additional characteristics
– critical characteristics to be controlled to ensure consistent
performance of the API (e.g. hygroscopicity)
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties: Compendial APIs

Physico-chemical and other relevant properties, e.g.
– Solubility in water (effect of pH), other solvents such as ether,
ethanol, acetone and dichloromethane
– pKa, partition coefficient
– Existence/absence of polymorphs and pseudo-polymorphs e.g.
solvates (with XRPD, DSC, IR)
• e.g. Rifampicin polymorphs I and II
– Hygroscopicity
– Particle size
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Properties of API(s)
 Categories of Antimalarials
– APIs described in monographs of major international
pharmacopoeias ( 10 years)
• Amodiaquine, Chloroquine, Dapsone, Quinine, Mefloquine,
Sulfadoxine/Pyrimethamine, Trimethoprim
– APIs described in monographs of major international
pharmacopoeias (recently)
• Arthemether, Artemisinin, Artemotil, Artenimol, Artesunate
– APIs not described in monographs of major international
pharmacopoeias
• Chlorproguanil, Lumefantrine, Naphthoquine, Piperaquine, Pyronaridine
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Malaria APIs: Table of occurrence
API
BP
EP
US
Int
JP
MI
Artemether
✓*
✓
Artemisinin
✓*
✓
Artemotil (arteether)
✓*
✓
Artenimol
✓*
✗
Artesunate
✓*
✓
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Active Pharmaceutical Ingredients - Artemisinin based therapy
APr
Cod
18
Malaria APIs: Table of occurrence (con.)
API
BP
EP
Amodiaquine
US
Int
✓*
✓
Lumefantrine
JP
MI
APr
✓
✓
Cod
✓
Mefloquine
✓
✓
✓
✓
✓
✓
Pyrimethamine
✓*
✓
✓*
✓
✓
✓
Sulfadoxine
✓*
✓
✓*
✓
✓
✓
Lumefantrine only malaria API without monograph
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Active Pharmaceutical Ingredients - Artemisinin based therapy
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Properties of Artemisinins
 Artemisinin (C15H22O5)
–
–
–
–
7 centers of asymmetry
27 potential isomers
One isomer in biosynthesis
Chemical synthesis
• Feasible but uneconomical
 Chemical derivatization at
C-10 (carbonyl-moiety) converts
C-10 into an additional
stereoisomeric center:
•
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a- and b-isomers are formed
Active Pharmaceutical Ingredients - Artemisinin based therapy
8
9
7
8a
12a
6
10
11
12
5a
5
1
4
2
3
Properties of Artemisinins
Manufacturer proposals
Melting range
Specific optical rotation
a-Artemether
100°C
b-Artemether
84 - 86°C, 86 – 90°C
+166°-+173°, +168°-+173°
20mg/ml C2H5OH
a-Artesunate
144°C, 143°C, 142-146°C
132-135°C, 131-134°C
+2.5°-+3.5°, +4.5°-+6.5°, +11°-+14°
10mg/ml CH2Cl2
+11°-+14°, 40mg/ml CH3Cl, +10°-+14°
(CH3Cl)
b-Artesunate
132-135°C
+2.5°-+3.5°
a~b~Artenimol
(in solution)
+146° (15°C)
(?mg/ml MeOH)
Diastereomers may differ in their melting point/specific optical rotation
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Route(s) of synthesis
API not described in BP, Int.Ph., JP,Ph.Eur., or USP (non-compendial APIs)
– Controls of critical steps and intermediates
• Potential impact on the quality of the API and intermediates
– Process conditions, test requirements and other relevant parameters to be
controlled within predetermined limits
• Examples of potentially critical steps
– Mixing of multiple components
– Phase change and phase separation steps
– Steps where control of pH and temperature are critical
– Introduction of an essential structural element or major chemical
transformation
– Introduction/removal of significant impurities to the API
– Final purification step
– Steps with an impact on solid state properties/homogeneity of the API

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API described in BP, Int.Ph., JP, Ph.Eur.,
or USP (compendial APIs)
Active Pharmaceutical Ingredients - Artemisinin based therapy
Route(s) of synthesis (cont.)
 Requirements: The synthesis should
–
–
–
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lead to the correct structure, stereochemistry and crystal form
& size (if relevant)
be well controlled and validated (GMP)
produce an API which meets acceptable standards of quality,
including limits of impurities (organic, inorganic, residual
solvents)
Active Pharmaceutical Ingredients - Artemisinin based therapy
The information required for the synthesis of the API may
depend on
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
Availability of a valid CEP - no synthesis information is then
required. CEP must however have all appendices and applicant
to submit other info not covered by CEP

Whether the quality of the is API controlled by a monograph in
an acknowledged pharmacopoeia?

No official monograph is available for quality control
- Detailed information required e.g. Open Part of DMF (from API
manufacturer)
- Also signed declaration from API manuf that synthesis and purification
are as described in the dossier
Active Pharmaceutical Ingredients - Artemisinin based therapy
Certification Scheme /EDQM
CEP Option
 Issued by EDQM for substances described in the Ph. Eur.
www.edqm.eu under Certification.Pharm.Substances
 Information which can be found on a quality CEP
- CEP reference Number,
- CEP holder,
- Site of manufacture of the API, site of manufacture of declared starting
material
- Grade (particle size or sterile) (if applicable)
- Ph. Eur. monograph according to which the Certification dossier has been
evaluated,
- Additional impurities and residual solvents not mentioned in the
monograph,
- Additional methods to those of the monograph as annexes,
- If sterile API, Method of sterilization + mention that process and validation
have been assessed
- Re-test period (if applicable)
- Packaging system and storage condition (if re-test period mentioned),
- Date of validity of the CEP
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Certification Scheme /EDQM
CEP Option
A quality CEP certifies that the quality of the
substance can be checked according to the Ph. Eur.
by applying the analytical methods described in the
specific Ph. Eur. monograph supplemented by those
appended to the CEP.
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Synthesis : non-compendial APIs

A flow diagram of the synthesis process
 including structures & stereochemistry of starting materials & intermediates;
reagents; catalysts; solvents

A full description of each step / process, including:









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Reaction conditions (temp., time, moisture control, etc.)
Quantities of reagents/solvents
Size of production scale
Purification of intermediates
Final API purification method / crystallisation / solvent(s)
Reprocessing (has to be justified, validated)
Process controls
Validation of critical steps, e.g. aseptic processes
Discussion of (possible) process impurities
 Organic, residual solvents and catalysts/inorganic
Active Pharmaceutical Ingredients - Artemisinin based therapy
API described in BP, PhInt, PhEur or USP
– Impurities that are not included in the monograph
• Process related impurities
– Key intermediates
– Residual solvents
– Potential organic impurities not covered by the monograph
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Specifications of raw materials and intermediates used in
synthesis
Provide specifications for


starting materials and intermediates (if isolated)
reagents, solvents & catalysts
Class 1 solvents should not be used (ICH Q3C)

Benzene, Carbon tetrachloride, 1,2-Dichloroethane,
1,1-Dichloroethene & 1,1,1-Trichloroethane
Provide a declaration on the use/non-use of material of animal or
human origin (TSE)

Risk of Transmitting Animal Spongiform Encephalopathy Agents (WHO
TRS 908, Annex 1 or EMEA/410/01 Rev.2)
To limit impurities in the API (For safety reasons)
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Active Pharmaceutical Ingredients - Artemisinin based therapy
WHAT IS A STARTING MATERIAL?
 Contributes an important structural part of the API
 Available in free trade
 Compound well defined in chemical literature (name, chemical
structure, chemical and physical properties, and impurity profile)
 Synthesized by commonly known process
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Active Pharmaceutical Ingredients - Artemisinin based therapy
RE-DEFINITION OF STARTING MATERIAL
MARKS THE START OF THE MANUFACTURING PROCESS
DESCRIBED IN AN APPLICATION
 Manufacturing steps before are not described
 Manufacturing steps before need not be performed in
accordance with GMP
 Changes in manufacturing steps before need not be reported
to WHO
EACH BRANCH OF A SYNTHESIS WILL BEGIN WITH ONE OR MORE
STARTING MATERIALS
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Active Pharmaceutical Ingredients - Artemisinin based therapy
API specifications
API not described in BP, Int.Ph., JP, Ph.Eur., or USP (non-compendial
APIs)
API described in BP, Int.Ph., JP, Ph.Eur.,
or USP (compendial APIs)
General note
An API has only one set of specifications applicable at release and
throughout the re-test period
– an FPP may have two sets of specifications – release and shelf-life
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Specifications: Non-Compendial APIs
ICH Q6A (new APIs and products) – for instance:

Requires justification for proposed specifications

Impurities to be characterised and limits set


synthesis and degradation according to ICH Q3A(R)
residual solvents according to ICH Q3C

Analytical methods with validation

Preparation and potency determination/specification of primary
and secondary (working) standards, with CoAs
Valid CoAs for at least 2 batches
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Non-compendial APIs
Typical set of specifications

Appearance/description

Identification (at least one specific, e.g. IR spectrum)

Moisture content (or LOD: moisture + residual solvents)

Impurities
- Related organic substances (synthesis or degradation)
 specified
 unspecified and
 total organic impurities
- Inorganic impurities, including catalysts
- Residual solvent(s)

Assay

Additional parameters important for specific API

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such as particle size, polymorphic form, microbial limits
Active Pharmaceutical Ingredients - Artemisinin based therapy
Specs: Compendial APIs
 The current monograph always applicable
 Additional critical specifications that are not included in monograph
e.g.
– particle size & polymorphic form
– synthesis related impurities resulting from specific process which may be
additional to monograph
– residual solvents (specific to process)
 Valid CoAs for at least 2 batches required
CEP normally states tests additional to the monograph
– e.g. residual solvents & impurities
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Active Pharmaceutical Ingredients - Artemisinin based therapy
IMPURITIES
 Extraneous contaminant (foreign substances)
 Toxic impurities
 Concomitant components
 Signal impurities
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Classes of Impurities
Organic
Inorganic
Residual solvents
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Organic Impurities
May arise during manufacturing process and storage
 Starting materials
 By products
 Intermediates
 Degradation products
 Reagents, ligands and catalysts
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Inorganic Impurities
May be from manufacturing process and are normally
known and identified:
 Reagents, ligands and catalysts
 Heavy metals
 Inorganic salts
 other materials (e.g. filter aids, charcoal etc.)
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Solvents
Organic or inorganic liquids used during the manufacturing
process
Toxicity generally known, therefore controls achievable
Limits to be based on pharmacopoeial standards or known
safety data
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Active Pharmaceutical Ingredients - Artemisinin based therapy
IMPURITIES
 Identified impurity
 Unidentified impurity
 Specified impurity
 Unspecified impurity
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Impurity Thresholds
Identification threshold Limit above which, impurities found are to be identified
either structurally or by a qualitative parameter e.g. RT in HPLC system
Qualification threshold Limit above which, impurities found are to be
toxicologically qualified
Reporting threshold Limit from which, impurities should be analytically reported
Maximum Daily
Dose
Reporting
Threshold
Identification
Threshold
Qualification
Threshold
≤ 2g/day
0.05%
0.10% or 1mg per
0.15% or 1mg per
day intake (whichever is
day intake (whichever is
lower)
lower)
0.05%
0.05%
≥ 2g/day
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0.03%
Active Pharmaceutical Ingredients - Artemisinin based therapy
ICH Guidelines for Identification and Qualification of
impurities in bulk drugs and FPPs
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Active Pharmaceutical Ingredients - Artemisinin based therapy
IMPURITY EQUIVALENCE
To demonstrate that different sources of the API or routes of
synthesis are equivalent, checks on impurities are required to
show that
 No new impurity is observed in the intermediate above 0.1%
 No new impurity is observed in API above the qualification
threshold
 Each existing impurity is within its stated limit
 Total impurities are within the stated limit
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Active Pharmaceutical Ingredients - Artemisinin based therapy
IMPURITY EQUIVALENCE (2)
 Each existing residual solvent is within its stated limit
 New residual solvents, in either an intermediate or the
API, are at or below the levels recommended in the ICH
guide
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Active Pharmaceutical Ingredients - Artemisinin based therapy
IMPURITY EQUIVALENCE (3)
Ideally, impurities should be evaluated in isolated
intermediates immediately following the process step in
which they are produced
The impurity search can be extended to the next
downstream intermediate and the evaluation process
repeated until the final intermediate, even to the API
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Potential impurities of Artemisinins
 Starting material (extracted from herbal sources)
– GuideGeneric:
• Starting materials from vegetable origin should be fully characterized and
a contaminant profile should be established and submitted.
– CPMP/QWP/297/97 Rev 1 corr:
• In the case of substances isolated form herbal sources, the potential for
impurities arising from cultivation and/or preparation (e.g. pesticide
residues, fumigants, mycotoxins) should be addressed.
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Potential impurities of Artemisinins II
 Impurities contained in the starting material - Artemisinin
– Biosynthetic by-products
• Arteannuin B , Artemisitene, Artemisinic acid,
– Extraction from fresh leaves with CHCl3 within 1 min > 97%
Localisation in subcuticular space of the glands on the »
surface of the leaves
– Cultivation reagents
• Pesticide residues, fumigants, mycotoxins
– Solvents from the extraction process
• Hexane, benzene, acetonitril, ether, pentane, chloroforme…..(?) diesel, fuel
(?) [ICH Q3A (R)]
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Potential impurities of Artemisinins III
 Unreacted starting material
– Artemisinin (starting material for derivatives)
– Artemisinic acid (starting matrial for dihydroartemisinin)
– Dihydroartemisinin (starting material for derivatives)
 Unreacted intermediates, by-products
– a-Arthemether, a-Artheether
– a/b-Dihydroartemisinin
– b-Artesunate
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Potential impurities of Artemisinins III cont.
 Reagents, catalysts, residual solvents
– Methanol, acetonitril, chloroforme, acetone …
– NaBH4, succinic acid/anhydride, triethylamine,
dimethylaminopyridine
 Degradants
– Stability of
• ester-derivative (Artesunate)
• ether-derivative (Artemether, Arteether)
• lactone (Artemisinin)
– Stability of artenimol (oxidation)
– Susceptibility of endoperoxide bond to reduction
• Deoxyartemisinine (loss of active principle!)
– Zn / AcOH or FeBr2 / THF
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Site(s) of manufacture
 The quality of APIs is dependent on
– Manufacturing site
• Equipment, personal, technology…
– Route of synthesis, operational conditions, IPCs…
• Impurity profile, stability (API & FPP)
 The quality of an API may consequently impact the quality of a FPP
– Change in manufacturing site
• Alternate API-manufacturers
– Change in route of synthesis
• Alternate API-manufacturers
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Stability testing
Stress testing of API (forced degradation) helps
 to identify the likely degradation products and pathways
 to establish stability of the molecule
 To verify specificity of stability assay method
 e.g. Diode array detection for API peak purity !
Stability testing (regulatory) to provide evidence on
 how the quality of an API varies with time
under the influence of a variety of environmental factors such as
temperature, humidity, and light; and
 to establish a re-test period for the API and
 to recommended storage conditions
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Stress testing (forced degradation)
Typical conditions
The conditions should
 partially (e.g. 10-30%)
decompose the API to
primary degradation
products
 Conditions can be
changed to get required
degree of degradation
** Temperature should not
come closer than 10°C
from melting point
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Stress factor
Conditions (e.g.)
Humidity
≥ 75% RH (solid)
Heat **
≥ 60°C (solid)
Heat
water
Acid
0.1 M HCl
Base
0.1 M NaOH
Oxidative
3% H2O2
Photolytic
ICH Q1B
Metal ions
(optional)
0.05 M Fe2+ or Cu2+
Active Pharmaceutical Ingredients - Artemisinin based therapy
Stress testing (forced degradation)
Literature

Literature information and/or CEP
–
–
54 |
in support of and/or
to replace experimental data
Active Pharmaceutical Ingredients - Artemisinin based therapy
Important Elements
 The API must be of required structure & stereochemistry
 The physical properties must be well understood, e.g.
– hygroscopicity, crystal properties and solubility
 The synthesis process must be according to GMP to
– consistently produce an API of required chemical and physical
quality
– limit impurities according to defined standards
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Active Pharmaceutical Ingredients - Artemisinin based therapy
Important Elements (2)
The set of specifications should



56 |
be based on validated analytical methods
with appropriate acceptance criteria
to which an API should conform to be considered acceptable
for its intended use throughout the retest period in the proposed
packaging
Active Pharmaceutical Ingredients - Artemisinin based therapy