1. Pharmaceutical Research and Development Considerations
Workshop on GMP and Quality Assurance of
Multisource Tuberculosis Medicines
Kuala Lumpur – Malaysia
21-25 February 2005
Pharmaceutical Research and Development Considerations
Theo Dekker, D.Sc., consultant to WHO
Research Institute for Industrial Pharmacy
North-West University, Potchefstroom, South Africa

2. Abbreviations API Active pharmaceutical ingredient
BCS Biopharmaceutics classification system
BP British Pharmacopoeia
CEP EU certificate of suitability
EOI Expression of interest
FDC Fixed dose combination
FPP Finished pharmaceutical product
ICH International Conference on Harmonization
Int.Ph. International Pharmacopoeia
R&D Research and development
TB Tuberculosis
XRPD X-ray powder diffractogram
USP United States Pharmacopeia

3. The perspective
Pharmaceutical R & D provides the foundation of the activities aimed at ensuring that the patient receives an FPP (product) that consistently meets established standards & specifications of
Safety
Efficacy
Quality
The FPP should be stable - and thus retain these standards – throughout the shelf-life,
if kept in the original packaging
when correctly distributed, stored & handled

4. Pharmaceutical R&D Learn about the product through desk research:
Don’t try to reinvent the wheel
Collect & analyse available information on e.g. APIs, formulas, excipients, compatibility, stability, dosage form, strength, packaging & analysis
Compile a Product Profile Report
Development according to plan, including:
Preformulation studies
Formula / dosage form development & packaging
Comparative dissolution against comparator FPP
Accelerated stability
Final formula / manufacturing process

5. Topics for discussion Desk research – Product Profile Report
The FDCs anti-tuberculosis tablets – a problem mix
API-API interactions of particular importance
Solid state properties of APIs
Rifampicin as example
Biowaiver type of comparative dissolutions
Formulation development & comparison of pivotal batches
Setting product dissolution specifications
Pre-BE control
Post-approval changes

6. Product profile report
Objective
To compile a comprehensive summary, with conclusions, of all available information that may be important for the development of the product
To have a standard (pro-forma) style for the report, facilitating compilation/application
Assign experts in preparation of relevant parts
To use this report as base for development pharmaceutics (though considered part thereof)
Example
4FDC anti-tuberculosis tablets

7. Typical product profile report (1)
PRODUCT UNDER CONSIDERATION
4FDC anti-tuberculosis solid oral dosage form
Reference product(s) information
Category
Anti-tuberculosis agent
WHO model list of essential drugs (current)
Rifampicin 150 mg, Isoniazid 75 mg, Pyrazin-amide 400 mg & Ethambutol 2HCl 275 mg
Prequalification EOI requirement (current)
As for WHO model list – as tablets

8. Typical product profile report (2)
Prequalified products according to current list
Wyeth Pakistan - tablet (blister)
Lupin India – tablet (blister, HDPE bottle)
Sandoz – tablet (blister)
Public assessment reports available
None (FDA, EPAR, WHOPAR)
Comparator product (bio-section)
Sandoz (registered in Sweden)? Clarify
Combination of loose tablets? Clarify
Other products with “marketing authorisation”
List such products, where considered necessary

9. Typical product profile report (3)
Products available for inspection/testing
Wyeth Pak, Lupin, Sandoz, others
Comparator for comparing dissolution profiles
Description/appearance of reference products
Especially the prequalified products (i.a. for patient compliance)
Product A: Red oblong film-coated tablets, etc.
Packaging / pack sizes
Prequalified products important (see website)
HDPE bottles (100s?), 3 x 10 blisters (alu/alu?)?

10. Typical product profile report (4)
Storage requirements /shelf life
Especially the prequalified 4FDC tablets
From SmPC or PIL
Published product specific excipients
Tabulate for all prequalified/registered products where available (table for comparative purposes)
Public assessment reports (not available for the 4FDC tablets)
From SmPCs (also available on internet)
Document known incompatibilities with APIs

11. Typical product profile report (5)
Published formulas
Formulas are published for older products in standard works and journals (see next page)
Official product monographs
USP 28 (always current) for 4FDC
2 HPLC assay methods for all four APIs
Dissolution test for all four APIs
Related substances (degradants) not included
Safety & efficacy information
Requirements for BE studies
Comparator product(s)

12. Typical product profile report (6)
Typical books for formulation and excipients:
S. K. Niazi. Handbook of Pharmaceutical Manufacturing Formulations. CRC Press, Boca Raton (current edition):
Volume 1. Compressed Solid Products
Volume 2. Uncompressed Solid Products
Volume 3. Liquid Products
Volume 4. Semisolid Products
Volume 6. Sterile Products
Handbook of Pharmaceutical Excipients. A.H. Kibbe, ed. 3rd edition. American Pharmaceutical Association, Washington, 2000 (Pharmaceutical Press, London)

13. Typical product profile report (7)
API information
Nomenclature
INN, USAN, Systematic name , CAS, etc. from e.g. Merck Index for each API (standard)
General physical properties
Discuss/tabulate properties of each API in terms of the guidance for dossier requirements, with special attention to unique API properties, e.g.
Rifampicin (pseudo) polymorphism and dissolution
Hygroscopicity of ethambutol 2HCl
Comparison of solubilities (analytically important)

14. Typical product profile report (8)
Compedial monograph(s)
BP/Ph.Eur., Int.Ph. and USP for all 4 APIs
Stability & degradation routes
Compile expert report for each of the 4 APIs
Stress data and mild conditions from literature in: - solution and solid state
API/API and API/excipient interactions
Storage conditions and optimal analytical stability
Conclusions and precautions with respect to intended product

15. Typical product profile report (9)
Possible BCS classification
Biowaivers (in vitro dissolution instead of bioequivalence studies) for immediate release solid orals (tablets, capsules) are not in current prequalification guidelines. Biowaivers used for demonstration of equivalence of lower vs higher strength in proportional similar formulations.
FDA and EMEA guidelines exist for classification “rules”, dissolution requirements and similarity of profiles

16. Typical product profile report (10)
Recommendations
File hard copies of all sources in support of the Product Profile Report
The data in the Product Profile Report can be used inter alia:
To form the basis of development pharmaceutics & to identify further experimental investigations
To alert the development team of possible problems
To identify monograph & analytical shortcomings

17. 4FDC tablets – a problem mix (1)
Composition in current Essential Drug List
Rifampicin 150 mg
Isoniazid 75 mg
Pyrazinamide 400 mg
Ethambutol 2HCl 275 mg
Total API weight 900 mg
Typical tablet weight ~ 1.3 g

18. 4FDC tablets – a problem mix (2)
Rifampicin
Oxidation (quinone & N-oxide)
Protect from air exposure
Hydrolysis (3-formylrifamycin & 25-desacetyl)
Wet granulation / drying a potential problem?
Reaction with Isoniazid
3-(isonicotinylhydrazinomethyl)rifamycin or more commonly known as isonicotinyl hydrazone
isonicotinyl hydrazone major decomposition product
Light sensitive
Product to be protected from light exposure

19. 4FDC tablets – a problem mix (3)
hydrolysis Rifampicin
oxidation hydrolysis

20. 4FDC tablets – a problem mix (4)
Isoniazid
Reacts with aldehydes/reducing sugars
Sugar & lactose to be avoided in formulation !!
3-Formylrifamycin (from rifampicin)
Ethambutol hydrochloride (2HCl)
Hygroscopic
Absorbs water for reaction in tablets
Creates slightly acidic conditions
pH of 2% w/v solution: (BP)
The acidic conditions enhance rifampicin/isoniazid reaction (isonicotinyl hydrazone formation)

21. 4FDC tablets – a problem mix (5)
Isonicotinyl hydrazone (3-(isonicotinylhydrazinomethyl)rifamycin)
This is major decomposition product in tablets containing rifampicin and isoniazid
Series of articles by dr. S. Singh et al. (NIPER), e.g.
S. Singh, T. T. Mariappan, N. Sharda, S. Kumar & A. K. Chakraborti. The reason for an increase in decomposition of rifampicin in the presence of isoniazid under acid conditions. Pharm. Pharmacol. Commun., 6, (2000)
The reactions shown on next slide are from the above publication

22. 4FDC tablets – hydrazone formation

23. 4FDC-TB tablets exposed to 40°C/75%RH for one week
Two products. “Bleeding” may start after more exposure (in-house)
Control on left Control on left

24. 4FDC-TB tablets preventative/protective measures
Formulation - no sugar/lactose (isoniazid)
Separate granulation of rifampicin & isoniazid
Rifampicin as powder (not granulate)?
Prevent oxidation & hydrolysis
Low water content of tablet (USP ≤ 3.0%)
Protect product from moisture and oxygen
Non-permeable packaging
Do not remove from primary packaging
Avoid repackaging
Light protection
Differential formulation, e.g. delayed release & immediate release in one tablet ??

25. Rifampicin solid state properties
Rifampicin exist is 3 solid state forms:
Polymorph I
Polymorph II
Amorphous form
Commercial material contains:
Polymorph II (predominantly)
Mixture of polymorph II and amorphous form
Five commercial samples (A to E) in examples:
Sample A: Form II
Sample B: Form II
Sample C: Form II + amorph
Sample D: Form II + amorph
Sample E: Form II

26. Rifampicin - SEM photos
Sample A Sample D
Form II Form II + amorph

27. Rifampicin -XRPDs Top: Sample A (Form II – sharp signals)
Middle: Sample C (Form II + amorph – intensity drop)
Bottom: Amorphous form (no pattern)

28. Rifampicin – powder dissolution (1)
Medium: 0.1 M hydrochloric acid
Profiles of all samples are similar
Dissolves immediately in 0.1 M hydrochloric acid

29. Rifampicin – powder dissolution (2)
Medium: Phosphate buffer pH 7.4
Profiles A, B & E are similar (f2 ≥ 50)
Profiles C & D are similar (f2 ≥ 50) - dissolution incomplete
Profiles A, B, E dissimilar from profiles C,D (f2 < 50)
A, B, E (form II)
C, D Form II + Amorph

30. Rifampicin – powder dissolution (3)
Medium: Water
Profiles A, B & E are similar (f2 ≥ 50)
Profiles C & D are similar (f2 ≥ 50) - dissolution incomplete
Profiles A, B, E dissimilar from profiles C,D (f2 < 50)
A, B, E (form II)
C, D (form II + amorph)

31. Rifampicin - solid state conclusions
Solid state forms identifiable by means of XRPD
Dissolution rate is not different in 0.1 M HCl
Presence of amorphous form slows down dissolution at higher pH (f2 test)
Incomplete dissolution after 65 minutes !!
May fail USP tolerance at pH 6.8 (75% in 45 min.) ??
Agglomeration / wettability?
Comparative powder dissolution powerful tool for supplier selection
Reference:
S. Q. Henwood, M. M. de Villiers, W. Liebenberg, A.P. Lötter. Solubility and dissolution properties of generic rifampicin raw materials. Drug Dev. & Ind. Pharm. 26, (2000) (Research Institute for Industrial Pharm.)

32. Polymorphism – important situations
When it has a significant effect on the rate of dissolution of the API in water and biological fluid, that may affect the absorption of the API
Of special importance for practically insoluble APIs
When it can affect the manufacturing process, e.g. in the case of flow properties
Where the properties differs to such extent that different forms can be used in different dosage forms (nevirapine: anhydrate in tablets and the hemihydrate in suspensions)

33. BCS classification (1)
High solubility: Highest dose strength of API should be soluble in ≤ 250 ml water at 37ºC over the pH range
High permeability: Absolute bioavailability ≥ 90 % (presently) - apart from specific permeability studies
Limiting factors for biowaivers (see FDA & EMEA)
Class
Solubility
Permeability 1
High 2
Low 3 4

34. BCS classification (2) Data from: API (INN) Class Rifampicin
M Lindenberg, S. Kopp, J. B. Dressman. Classification of orally administered drugs on the World Health Organization Model list of Essential Medicines according to the biopharmaceutics classification system. Eur. J. Pharm. Biopharm., 58, (2004)
None of other TBs (mainly for injection, thus not classified) in 5th inv. for EOI in publication – a number of ARVs are
API (INN)
Class
Rifampicin
2 (tentative)
Isoniazid
1 (tentative)
Pyrazinamide 1
Ethambutol 2HCl
3 (tentative)

35. Biowaiver dissolution studies (1)
Conditions
Three media ml or less - all at 37°C
1. Buffer pH 1.2, SGF without enzymes or 0.1M HCl
2. Buffer pH 4.5
3: Buffer pH 6.8 or SIF without enzymes
Water may be used additionally (not instead of)
Paddle at 50 or basket at 100 rpm
Twelve units of each product in all 3 media
Dissolution samples collected at short intervals, e.g.
10, 15, 20, 30, 45 and 60 minutes
Analyse samples for all APIs

36. Biowaiver dissolution studies (2)
Evaluation of dissolution data
The profiles of the test and reference products must be similar in all three media for considering a biowaiver (for not doing BE)
The profiles of the two products in a particular medium is considered similar:
If the similarity factor f2 ≥ 50 (see FDA/EMEA for calc)
Not all values can be considered for calculation of f2 (see EMEA guideline) – only one point beyond 85% dissolution, for both APIs (point zero also excluded)
If both products show ≥ 85% dissolution in 15 minutes

37. Biowaiver type dissolution application
Important during development studies
Formulation selection. Comparison of different lab / development batches with innovator product.
Important for comparison of pivotal batches to demonstrate in vitro similarity
Aids in selecting FPP dissolution conditions/specification
Bioequivalence support
Ideal pre-bioequivalence control - profile similarity with comparator product good indication of BE
Biowaiver studies not in current prequalification guidelines.
Post-approval changes

38. Comparative dissolution example
Ethambutol hydrochloride/Isoniazid 400/150 mg Tablets
Four manufacturers (A, B, C & D)
Dissolution conditions:
Paddle, 50 rpm
Phosphate buffer pH 6.8, 500 ml, undegassed, 37ºC
Pull times: 10, 15, 20, 30, 45 & 60 minutes
Source: T.G. Dekker, E.Swanepoel, A-M Redelinghuys & E.C. van Tonder - unpublished

39. Ethambutol 2HCl & Isoniazid Tabs (1)

40. Ethambutol 2HCl & Isoniazid Tabs (2)

41. Ethambutol 2HCl & Isoniazid Tabs (3)
B,C D

42. Ethambutol 2HCl & Isoniazid Tabs (4)
Evaluation of dissolution data
The dissolution profiles of the APIs in a particular product are similar (this holds for all 4 products)
Both APIs are highly soluble (BCS definition)
The products show different dissolution rates
Dissolution rate A > B ≈ C >> D
Disintegration (min)
Dissolution rate related to disintegration time
f2 values show that B & C have similar profiles
Dissolution method discriminating
Typical type of results during pharmaceutical R&D

43. Some conclusions
Get to know you product through systematic desk research, e.g. Product Profile Report
Physical properties of APIs may be important for low soluble APIs, e.g. polymorphism & particle size
Powder dissolution testing may be useful for sourcing
Consider important API properties and API-API interactions, especially in FDCs in formulation
Packaging to be non-permeable and light protective
Biowaiver type dissolutions are important in:
Choice of formulation vs comparator
Comparison of pivotal batches
Setting product dissolution specifications
Pre-BE control
Post-approval changes