Presented by Rutendo Kuwana

1. Evaluation of quality and interchangeability of medicinal productsTraining workshop for evaluators from National Medicines Regulatory Authorities in East Africa Community10-14 September 2007, Dar Es Salaam, Tanzania Presented by Rutendo Kuwana Active pharmaceutical ingredients

2. What is an API? 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)

3. Presentation approach Collect and interpret available information on the APIs (pre dossier studies), such as: • Literature, all aspects (chemical/physical) • Monographs in pharmacopoeia (example: ARVs)

4. Some definitions Enantiomer 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

5. Some definitions (2) 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

6. Available information on API Applicants should collect and analyse available information of the API in a systematic approach Some outcomes: • Sound scientific understanding of the API, with respect to properties, stability, specifications, etc. • Assists in API manufacture and DMF compilation • Sound choice of API manufacturer (source) • Assists in dossier compilation • Important for FPP pharmaceutical development • Reduction of time / cost

7. 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

8. 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

9. Information from literature & structure: Rifampicin hydrolysis (to 25-desacetyl) oxidationhydrolysis (to quinone) (to 3-formyl) Oxidation to N oxide light sensitive

10. Information from literature & structure Rifampicin (discussion - 1) 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

11. Information from literature & structure Rifampicin (discussion - 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

12. Information from literature & structure Isoniazid Small molecule (quite stable) • Basic amino functions • Primary amine - reacts with aldehydes/lactose • see presentation: FPPs – formulation problems? • Can hydrolyze under stress conditions to e.g. isonicotinic acid & hydrazine • Oxidize in presence of strong oxidants (e.g. permanganate), with metals as catalyst

13. Information from literature & structure Indinavir sulfate Basic amino atoms (2) forms H2SO4 salt ethanol in crystal Unstable • 2 main degradation products • moisture and temp. sensitive • acid / base enhanced • Intra-molecular reaction + Kreutz, J. Pharm. Biomed. Anal., 19, 725-735 (1999) and Crixivan® EPAR

14. Literature support 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) • Photocopies of publication or relevant pages

15. Properties of APIs Scenarios: API not described in BP, Ph., JP, Ph.Eur., or USP (non - compendial) API described in BP, Int.Ph., JP, Ph.Eur.,or USP (compendial) Information from literature (important)

16. Properties: non-compendial APIs • Proof of structure/stereochemistry correctness • 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 or • correlation against API spectral data from peer reviewed literature, preferable innovator publication (in tabulated form!!). Strongly recommended • Physico-chemical properties

17. 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 • See Nevirapine (later in this presentation) • Hygroscopicity e.g. Ethambutol hydrochloride in FDC tablet • Particle size

18. Properties for Compendial APIsExample: solubility of TB APIs 1 Merck Index 13th ed 2 Pharmaceutical Codex 12th ed * Dichloromethane has similar properties to chloroform as solvent, but preferred for safety reasons

19. Properties APIsExample: solubility protease inhibitors(mg/ml) GC Williams & PJ Sinko, Advanced Drug Delivery Reviews, 39, 211-238 (1999)

20. Properties Compendial APIsPseudo-polymorphism nevirapine Int. Ph. monograph Nevirapine (anhydrous & hemihydrate) • Identification test C Carry out the examination as described under “Spectrophotometry in the infrared region”. • For the anhydrous substance, the infrared (IR) absorption spectrum is concordant with the spectrum obtained from anhydrous nevirapine RS or with the reference spectrum of anhydrous nevirapine • For the hemihydrate, the IR absorption spectrum shows a characteristic sharp absorbance at about 3503 cm−1; after heating the test substance for one hour at 140°C and cooling, the IR absorption spectrum is concordant with the spectrum obtained from anhydrous nevirapine RS or with the reference spectrum of anhydrous nevirapine

21. Properties Compendial APIsPseudo-polymorphism nevirapine (2) Interpretation of this IR identification test: • Nevirapine anhydrous (one test) • IR spectrum against nevirapine anhydrous RS • Nevirapine hemihydrate (two tests, conform to both) • IR spectrum shows signal at 3503 cm-1 (water) and • Heat converts the hemihydrate to the anhydrous form • IR spectrum against nevirapine anhydrous RS - ½H20 Nevirapine, ½H20 ————> Nevirapine heat The reaction is not reversible at room temperature

22. IR-spectra Nevirapine ½H20 3503 cm-1 O-H signal (water) • Spectra not concordant (do not match) Nevirapine anhydrous • no crystal water • no O-H signal

23. Route(s) of synthesis Scenarios: • API not described in BP, Int.Ph., JP,Ph.Eur., or USP(non-compendial APIs) • Specifications of raw materials and intermediates used in the synthesis of non-compendial APIs • API described in BP, Int.Ph., JP, Ph.Eur., or USP(compendial APIs)

24. Route(s) of synthesis (cont.) • Requirements: The synthesis should • 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)

25. The information required for the synthesis of the API may depend on • Is a valid CEP is available? - no synthesis information required. CEP must however have all appendices and applicant to submit other info not covered by CEP • Is the quality of the 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

26. 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: • 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

27. 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 (Safety reasons)

28. 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

29. 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 Agency EACH BRANCH OF A SYNTHESIS WILL BEGIN WITH ONE OR MORE STARTING MATERIALS

30. INDINAVIR

31. CHEMICAL SYNTHESIS • Indinavir is a chiral molecule with 5 stereogenic centers • Only stereoisomer observed in the API is the 4-(R)-epimer. • It is stereoselectively prepared in six steps. • The enantiomeric purity of the API and other ingredients is ensured by the route of manufacture and quality control on intermediate products (starting materials and intermediate indinavir free base) rather than a test for specific rotation.

32. CHEMICAL EQUIVALENCE (1) • The stereochemistry is well under control during the synthesis • Racemization after the synthesis is extremely unlikely • Formation of epimers cannot be excluded but should be detectable by the purity tests applied. • Potential impurities from synthesis, stereoisomeric impurities and degradants have been identified. Minimised or removed by control on the reaction parameters and in-process controls • High humidity, which leads to formation of degradants, is avoided.

33. CHEMICAL EQUIVALENCE (2) • The API is very pure • The limit for any single impurity is not more than 0.1 % • limit for the sum of all impurities is not more than 0.5 % • Due to the high doses to be given in clinical use (> 2 g/day), the qualification threshold as defined in the ICH guideline on impurities, is 0.05 %.

34. PHYSICOCHEMICAL EQUIVALENCE Indinavir Sulfate Ethanolate • Freely Soluble In Aqueous Solutions • PARTICLE SIZE Not Critical • No POLYMORPHISM • POOR FLOWABILITY • Relatively Loose Bulk Density

35. API STABILITY TESTS • Indinavir is highly hygroscopic at relative humidity above 60 % • In the presence of moisture and/or elevated temperatures, the API undergoes conversion to an amorphous material or to a hydrate crystal form and to the formation of degradation products i.e. lactone and several unidentified impurities occur • HVAC SYSTEM SHOULD MAINTAIN A RELATIVE HUMIDITY OF ≤ 33% AT 25OC

36. NEVIRAPINE

37. CHEMICAL STRUCTURE

38. CHEMICAL STRUCTURE • Nevirapine does not contain an assymetric carbon atom (a chiral centre) • The nitrogen in position 11 shows weekly basic properties • Other functional groups are not very reactive under everyday manufacturing environmental conditions

39. CHEMICAL INFORMATION C15H14N4O (anhydrate for tablets)266.30 C15H14N4O·1/2 H2O (hemihydrate for oral suspension)275.35 CAS number: 129618-40-2 NEVIRAPINE is lipophilic (partition coefficient 83) and is essentially nonionized at physiologic pH. As a weak base (pKa 2.8), NEVIRAPINE is known to be soluble at acidic pH values.

40. PHYSICO-CHEMICAL INFORMATION • Aqueous solubility (anhydrate) (90 μg/ml at 25°C). • NEVIRAPINE anhydrous is a white to off-white crystalline powder. • No potential toxicity was found in intermediates found in the synthesis of NEVIRAPINE • NEVIRAPINE is milled in order to obtain an acceptable particle size distribution.

41. SPECIFICATION, STABILITY • Innovator results showed that Nevirapine is highly stable even under stressed conditions over a 24 month study period • No degradants were detected and all the results remained within the specifications.

42. DESK CONCLUSION Critical API parameters: • Particle size of themicronized drug substance

43. 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

44. 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

45. Non-compendial APIsTypical 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 • such as particle size, polymorphic form, microbial limits

46. 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

47. IMPURITIES • Extraneous contaminant (foreign substances) • Toxic impurities • Concomitant components • Signal impurities

48. Classes of Impurities • Organic • Inorganic • Residual solvents

49. Organic Impurities May arise during manufacturing process and storage • Starting materials • By products • Intermediates • Degradation products • Reagents, ligands and catalysts

50. 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.)