Workshop on GMP and Quality Assurance of
Multisource Tuberculosis Medicines
Kuala Lumpur – Malaysia
21-25 February 2005
Active Pharmaceutical Ingredients
(APIs)
Theo Dekker, D.Sc., consultant to WHO
Research Institute for Industrial Pharmacy
North-West University, Potchefstroom, South Africa
iiftgd@puk.ac.za
Feb 2005
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TG Dekker – WHO, Malaysia
Abbreviations
API
BP
CEP
EOI
FDC
FPP
GMP
ICH
Int.Ph.
Ph.Eur.
SmPC
TB
USP
Feb 2005
Active pharmaceutical ingredient
British Pharmacopoeia
EU certificate of suitability
Expression of interest
Fixed dose combination
Finished pharmaceutical product
Good manufacturing practices
International Conference on Harmonization
International Pharmacopoeia
European Pharmacopoeia
Summary of product characteristics
Tuberculosis
United States Pharmacopeia
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Presentation approach
1. Collect and interpret all available information on
the APIs (pre-dossier studies):



The possible manufacturer(s)
Literature, all aspects
Monographs in pharmacopoeia
2. Dossier requirements






Feb 2005
Nomenclature
Properties
Manufacturing and site
Specifications
Container closure
Stability testing / re-test period
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Part 1. Available information on API
 Collecting and interpretation of all available
information of the API through a systematic
approach, should always be done upfront.
Some outcomes:
1. Sound choice of API source (manufacturer)
2. Sound scientific understanding of the API, with
respect to properties, stability, specifications, etc.
3. Assists in FPP pharmaceutical development
4. Assists in dossier compilation
5. Reduction of time / cost
 Forms part of Product Profile Report
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Info on potential API manufacturer(s)
The decision on the API manufacturer should
be finalised before starting or early during
FPP development studies

Changes afterwards may be major of nature
1. Is the manufacturer reliable / reputable?
2. Is the open part of DMF available and according to
all requirements?
3. Is a valid CEP available?
4. GMP inspection of API site by FPP manufacturer
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DMFs accepted & CEPs by Jan 2005
Number of manufacturers
API
DMF
CEP
Ethambutol 2HCl
2
1
Isoniazid
3
1
Pyrazinamide
3
3
Rifampicin
5
Streptomycin
1
Total
Feb 2005
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6
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Literature information
Know your API before development, through:
 Standard works / series / books – such as:



(Analytical) Profiles of Drug Substances and
Excipients [ed: (Florey) Brittain) – 30 volumes]
The Merck Index (for structures, properties)
Pharmaceutical Codex (12th edition)
 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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Feb 2005
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Examples of existing API information in
standard works
 In the table on the next pages it is indicated in which
standard works the APIs, appearing in the 5th
invitation for Expression of Interest (TB), is included.
Abbreviations:
 Apr = Analytical Profiles of Drug Substances and
Excipients (contains chapters on APIs)
 BP = British Pharmacopoeia
 Cod = Pharmaceutical Codex (12th ed, 1994)
 EP = Ph.Eur.
 Int = International Pharmacopoeia
 US = USP
 MI = Merck Index (13th ed, 2001)
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Table of API occurrence
API
APr Cod BP EP US
Int
MI
Rifampicin (rifampin)
✓
✓
✓
✓
✓
✓
✓
Ethambutol 2HCl
✓
✓
✓
✓
✓
✓
✓
Pyrazinamide
✓
✓
✓
✓
✓
✓
Isoniazid
✓
✓
✓
✓
✓
✓
Streptomycin sulfate
✓
✓
✓
✓
✓
✓
Amikacin
✓
✓
✓
✓
✓
✓
Kanamycin
✓
✓
✓
✓
✓
✓
✓
Capreomycin
Feb 2005
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✓
✓
✓
TG Dekker – WHO, Malaysia
Table of API occurrence (con.)
API
Cycloserine
APr Cod BP EP US Int
✓
✓
Ethionamide
✓
✓
✓
Ofloxacin
✓
✓
✓
p-Aminosalicylic acid
✓
✓
✓
✓
✓
✓
Protionamide
MI
✓
✓
✓
✓
Moxifloxacin
Apology: JP was not available at time of preparation
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Example: solubility from
2 literature sources
API
Rifampicin
Ethambutol 2HCl
Ethambutol base
Isoniazid
Pyrazinamide
1
Water
CHCl3
Ethanol
Water: Slightly 1,2
pH 7.5: 0.3% 2
pH 5.3: 0.4% 2
pH 2.0: 10% 2
50% 2
Sparingly 2
14% 1
1.5% 1
Freely 1,2
Slightly 2
0.1% 2
Very 2
0.1% 1
0.7% 1
20% 2
Merck Index 13th ed
Feb 2005
2
2% 1
0.6% 2
Pharmaceutical Codex 12th ed
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Information from the 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
 It is thus always appropriate to analyse the
structure of the API, especially if limited
literature information is available
 Few examples to follow
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Rifampicin structure
hydrolysis
oxidation
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hydrolysis
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3-Formyl rifamycin formation
Source: S. Singh et al. Pharm. Pharmacol. Commun., 6, 405-410 (2000)
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Rifampicin structure and properties
Oxidation
 Hydroquinone group
 Main degradation of API (to rifampicin quinone)
 Enhances solubility in alkaline medium
 Tertiary amine
 Moderately prone towards oxidation (to N-oxide)
 Enhances solubility in acid medium
 Oxidation enhanced by
 Metal ions
 Low pH
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Rifampicin structure and properties (2)
Hydrolysis
 Hydrazone (imine) group
 Hydrolysis to 3-formyl rifamycin
 25-acetyl (ester) group
 Hydrolysis to 25-desacetyl rifampicin (minor)
Light sensitive
 Due to conjugation in molecule (unsaturated)
Storage of bulk raw material (BP/Ph.Eur.):
 Store under nitrogen in an airtight container,
protected from light at temperature of ≤ 25ºC
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Rifampicin impurities (TLC)
 Reference: Int.Ph. related
substances test for rifampicin
• Silica gel R1
• CHCl3/methanol : 85/15
• Daylight detection
 BP limits for capsules:a) Rifampicin: 20 mg/ml
b) Quinone: 0.8 mg/ml (4.0%)
c) N-oxide:0.3 mg/ml (1.5%)
d) 3-Formylrifamycin: 0.1 mg/ml
(0.5%)
e) Rifampicin: 0.2 mg/ml (1.0%)
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Isoniazid structure
Small molecule (quite stable)
 Basic amino functions
 Primary amine - react with aldehydes/lactose (see
presentation: Pharmaceutical R&D Considerations)
 Can hydrolyze under stress conditions to inter alia
isonicotinic acid & hydrazine
 Oxidize in presence of strong oxidants (e.g.
permanganate), with metals as catalyst
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Pyrazinamide structure
Small molecule (quite stable)
 Basic amino functions (in aromatic ring)
 Amide group can hydrolyse under strong conditions to
pyrazinoic acid & ammonia
 USP ID test C: Boil 20 mg with 5 ml of 5 N sodium
hydroxide: the odor of ammonia is perceptible
 Forms metal complexes (slight pink bulk API / product?)
 Sublimes when heated
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Pyrazinamide synthesis
 Reagents: NaOH, water as solvent, touch of EDTA
 Product directly crystallised from the reaction mixture
 No residual solvents (only water used)
 2-CPZ to be included as a possible synthesis impurity in
API specifications
 EDTA for metal complexation (prevent colouration)
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Ethambutol hydrochloride structure
Small molecule
 Basic amino groups (in free base)
 No vulnerable groups for degradation under mild
conditions (2-aminobutanol – synthesis impurity)
 2 chiral carbon atoms, optically active (test)
 Hygroscopic (solubility in water: 50% m/m)
 Can dissolve in absorbed water at high relative humidity
 Forms metal complexes
 USP: Preserve in well-closed containers
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p-Aminosalicylic acid
+ CO2








Carboxylic acid and phenolic group: acidic
Weak basic group (amphoteric)
Saturated solution: pH of 3.0-3.5 (USP)
Sodium salt available (monograph in USP)
Labile: Decarboxylate when heated
Limit test for m-aminophenol in USP (API & tablets)
More stable in alkaline medium than in acid medium
Store in cool place!!
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Cycloserine
R-configuration
 Optically active







H20
Stable in anhydrous solid state, protected from water
Degrades in solution, or when solid is exposed to moisture
Pathway1: Dimerisation through one molecule attacking other
Pathway 2: Hydrolysis to ß-aminoxy-D-alanine
Stability: alkaline medium > neutral >> acid medium
Dissolution medium capsules: buffer pH 6.8 !!! (USP)
Primary amine: react with aldehydes/ketones
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Ofloxacin
Moxifloxacin
 Structurally related as encircled (see also ciprofloxacin)
 Both APIs contain acid and basic groups
 Chirality: both intrinsic chiral (optically active)
 Ofloxacin: 1 chiral centre: racemate (±) used
 Moxifloxacin: 2 chiral centra: S,S-enatiomer used
 Both APIs have enone system (in circle): photosensitive?
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Amikacin – semi synthetic
Kanamycin
APIs differ only here
4 x NH2 groups, 2H2SO4 salt
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hydrolysis
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Literature information sources
The information on the APIs mentioned in the
previous slides are backed by inter alia:
 Analytical Profiles of Drug Substances and
Excipients (ed: Florey/ Brittain) (see next slide)
 The Pharmaceutical Codex: Principles and
Practice of Pharmaceutics. 1994. Lund, W., ed.
12th edition, London: The Pharmaceutical Press
 The Merck Index, 13th edition (2001)
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Literature support style
Literature information used in the dossier should
always be accompanied by
 Full traceable reference citations, for instance:
 Devani, M.B., Shishoo, C.J., Doshi, K.J. & Patel,
H.B. Kinetic studies of the interaction between
isoniazid and reducing sugars. Journal of
Pharmaceutical Sciences, 74, 427-432 (1985)
 Hassan, M.M.A., Jado, A.I., & Zubair, M.U.
Aminosalicylic acid. In Florey, K., ed. Analytical
Profiles of Drug Substances, vol. 10. New York:
Academic Press, p. 1-27 (1981)
 Photocopies of the relevant pages
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Part 2. Dossier requirements for
Active pharmaceutical ingredient (API)
Refer to Section 2 of:
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 (hand-out)
As from page 3/33
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Part 2. Dossier requirements for
Active pharmaceutical ingredient (API) 3/33
2.1
2.2
2.3
2.4
2.5
2.6
2.7
Nomenclature (INN, Systematic, CAS, etc.)
Properties (structure, stereochemistry, etc)
Site of manufacture
Route of synthesis (impurities, etc)
Specifications (pharmacopoeia?)
Container closure system
Stability testing – re-test period & storage
-
 Open part of Drug Master File - submit (DMF)
 CEP (only limited information required)
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2.2 Properties of APIs 3/33
Three aspects:
2.2.1 API not described in BP, Int.Ph., JP,
Ph.Eur., or USP (non-compendial)
2.2.2 API described in BP, Int.Ph., JP, Ph.Eur.,
or USP (compendial)
2.2.3 Information from literature (discussed)
 All the APIs on 5th Invitation for EOI fall in
category 2.2.2, except moxifloxacin
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2.2.1 Properties non-compendial APIs
 Structure, stereochemistry, MF and RMM
 Proof of structure/stereochemistry correctness
 Single crystal X-ray structure (sufficient) or
 Spectrometric data (IR, 1H & 13C NMR, MS, etc.) in form of
QA certified copies of the spectra and tabulated of data
with
- assignments against structure or
- correlation against API spectral data from peer
reviewed literature, preferable by the innovator (in
tabulated form!!). Strongly recommended for
non-compendial APIs
 Physico-chemical properties as discussed on next
slide
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2.2.2 Properties compendial APIs
 Physicochemical and other relevant properties of the
API, such as
 Solubility in water, other solvents such as ether, ethanol,
acetone, and buffers of different pH
 pKa, partition coefficient
 Existence/absence of polymorphs and pseudo-polymorphs
e.g. solvates (with XRPD, DSC, IR)
 Polymorphism: see presentation Pharmaceutical R&D
Considerations (rifampicin)
 Hygroscopicity: see presentation Pharmaceutical R&D
Considerations (ethambutol hydrochloride in 4FDC tablet)
 Particle size
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2.3 Sites of manufacture 3/33
For each facility where all/part of
manufacturing occurs:





Feb 2005
Name of manufacturer
Street address
Postal address
Phone & fax numbers
E-mail addresses
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2.4 Route(s) of synthesis 4/33
Three aspects:
2.4.1 API not described in BP, Int.Ph., JP,
Ph.Eur., or USP (non-compendial)
2.4.2 API described in BP, Int.Ph., JP, Ph.Eur.,
or USP (compendial)
2.4.3 Specifications of raw materials and
intermediates used in the synthesis
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2.4.1 Synthesis non-compendial APIs
 A flow diagram of the synthesis process, that
includes inter alia chemical structures of starting
materials and intermediates, reagents, catalysts,
conditions, solvents and purification steps
 Example: see pyrazinamide synthesis (slide 21)
 A full description of each process, including
purification and reprocessing (justified)
 (Possible) process impurities should be discussed:
 Organic compounds
 Catalysts and other inorganic impurities
 Residual solvents
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2.4.2 Synthesis compendial APIs
 Valid CEP available
 Only outline of synthesis necessary
 No CEP
 Same as for non-compendial APIs
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2.5 API specifications 4/33
2.5.1 API not described in BP, Int.Ph., JP,
Ph.Eur., or USP (non-compendial)
2.5.2 API described in BP, Int.Ph., JP, Ph.Eur.,
or USP (compendial)
General note
An API has only one set of specifications,
applicable at release and throughout the retest period (FPPs may have two sets of
specifications)
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2.5.1 Specs: non-compendial APIs
ICH Q6A (new APIs and products) – for instance:
 Provide justification for proposed specifications
 Impurities (synthesis, degradation & residual
solvents) to be characterised and limits set
 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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2.5.2 Specs: compendial APIs
 Additional critical specifications not included in
monograph e.g.
 particle size & polymorphic form
 synthesis related impurities
 residual solvents
 Valid CoAs for at least 2 batches
2.5.3 Container-closure system for API 4/33
 see guideline
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2.7 Stability testing 6/33
2.7.1 Stress testing (forced degradation)
2.7.2 Stability testing (regulatory)
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2.7.1 Forced degradation
 Literature information and/or CEP in support or
to replace studies
 Forced degradation studies
 To identify possible degradants for stability studies
 To verify specificity of stability assay method
- Diode array detection for API peak purity!!
 Different stress conditions in solution (guideline)
 Different stress conditions in solid state
(guideline)
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2.7.2 Stability testing (regulatory)
 Only degradants that form under the real-time
and accelerated conditions needs to be
considered
 Stability protocol, particulars of batches (3),
tabulated results and discussion of data
 Typical schedule given under FPPs
 Propose re-test period when stored under
defined conditions
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Some conclusions
1. Get to know your API by




Analysis of literature information
Analysis of the structures / functional groups
Lab studies, e.g. forced degradation, spectral
data and physical data
Considering the dossier requirements
2. Decision on API manufacturer should include

DMF quality, GMP inspection, CEP availability
3. API manufacturers are encouraged to apply
for CEPs for their APIs
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