1 TG Dekker – WHO, MalaysiaFeb 2005 Active Pharmaceutical Ingredients (APIs) Workshop on GMP and...

1 TG Dekker – WHO, MalaysiaFeb 2005

Active Pharmaceutical Ingredients (APIs)

Workshop on GMP and Quality Assurance of

Multisource Tuberculosis MedicinesKuala Lumpur – Malaysia

21-25 February 2005

Theo Dekker, D.Sc., consultant to WHOResearch Institute for Industrial Pharmacy

North-West University, Potchefstroom, South [email protected]


Abbreviations

API Active pharmaceutical ingredientBP British PharmacopoeiaCEP EU certificate of suitabilityEOI Expression of interestFDC Fixed dose combinationFPP Finished pharmaceutical productGMP Good manufacturing practicesICH International Conference on HarmonizationInt.Ph. International PharmacopoeiaPh.Eur. European PharmacopoeiaSmPC Summary of product characteristicsTB TuberculosisUSP United States Pharmacopeia


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 Nomenclature Properties Manufacturing and site Specifications Container closure Stability testing / re-test period


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 development4. Assists in dossier compilation5. Reduction of time / cost

Forms part of Product Profile Report


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


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 14 5


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


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)


Table of API occurrence

API APr Cod BP EP US Int MI

Rifampicin (rifampin) ✓ ✓ ✓ ✓ ✓ ✓ ✓

Ethambutol 2HCl ✓ ✓ ✓ ✓ ✓ ✓ ✓

Pyrazinamide ✓ ✓ ✓ ✓ ✓ ✓

Isoniazid ✓ ✓ ✓ ✓ ✓ ✓ ✓

Streptomycin sulfate ✓ ✓ ✓ ✓ ✓ ✓

Amikacin ✓ ✓ ✓ ✓ ✓ ✓ ✓

Kanamycin ✓ ✓ ✓ ✓ ✓

Capreomycin ✓ ✓ ✓


Table of API occurrence (con.)

Apology: JP was not available at time of preparation

API APr Cod BP EP US Int MI

Cycloserine ✓ ✓ ✓

Ethionamide ✓ ✓ ✓ ✓ ✓

Ofloxacin ✓ ✓ ✓ ✓

Protionamide ✓ ✓

p-Aminosalicylic acid ✓ ✓ ✓

Moxifloxacin ✓


Example: solubility from2 literature sources

1 Merck Index 13th ed 2 Pharmaceutical Codex 12th ed

API Water CHCl3 Ethanol

Rifampicin Water: Slightly 1,2

pH 7.5: 0.3% 2

pH 5.3: 0.4% 2

pH 2.0: 10% 2

Freely 1,2 Slightly 2

Ethambutol 2HCl 50% 2 0.1% 2 20% 2

Ethambutol base Sparingly 2 Very 2

Isoniazid 14% 1 0.1% 1 2% 1

Pyrazinamide 1.5% 1 0.7% 1 0.6% 2


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


Rifampicin structure

hydrolysis

oxidation hydrolysis


3-Formyl rifamycin formation

Source: S. Singh et al. Pharm. Pharmacol. Commun., 6, 405-410 (2000)


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


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


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%)


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


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


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)


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


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!!


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


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?


Amikacin – semi synthetic

Kanamycin

APIs differ only here

4 x NH2 groups, 2H2SO4 salt hydrolysis


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)


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


Part 2. Dossier requirements for Active pharmaceutical ingredient (API)

Refer to Section 2 of:

Guideline on Submission of Documentationfor 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


Part 2. Dossier requirements for Active pharmaceutical ingredient (API) 3/33

2.1 Nomenclature (INN, Systematic, CAS, etc.)2.2 Properties (structure, stereochemistry, etc)2.3 Site of manufacture2.4 Route of synthesis (impurities, etc)2.5 Specifications (pharmacopoeia?)2.6 Container closure system2.7 Stability testing – re-test period & storage-

Open part of Drug Master File - submit (DMF) CEP (only limited information required)


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


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


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


2.3 Sites of manufacture 3/33

For each facility where all/part of manufacturing occurs: Name of manufacturer Street address Postal address Phone & fax numbers E-mail addresses


2.4 Route(s) of synthesis 4/33

Three aspects:



2.4.3 Specifications of raw materials and intermediates used in the synthesis


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


2.4.2 Synthesis compendial APIs

Valid CEP available Only outline of synthesis necessary

No CEP Same as for non-compendial APIs


2.5 API specifications 4/33



General note

An API has only one set of specifications, applicable at release and throughout the re-test period (FPPs may have two sets of specifications)


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


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


2.7 Stability testing 6/33

2.7.1 Stress testing (forced degradation)

2.7.2 Stability testing (regulatory)


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)


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


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

1 TG Dekker – WHO, MalaysiaFeb 2005 Active Pharmaceutical Ingredients (APIs) Workshop on GMP and...

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