1 TG Dekker – WHO, MalaysiaFeb 2005 Stability Studies (emphasis on FPPs) Workshop on GMP and Quality Assurance of Multisource Tuberculosis Medicines Kuala Lumpur – Malaysia February 2005 Theo Dekker, D.Sc., consultant to WHO Research Institute for Industrial Pharmacy North-West University, Potchefstroom, South Africa

2 TG Dekker – WHO, MalaysiaFeb 2005 Abbreviations APIActive pharmaceutical ingredient BPBritish Pharmacopoeia CEPEU certificate of suitability EOIExpression of interest FDCFixed dose combination FPPFinished pharmaceutical product ICHInternational Conference on Harmonization Int.Ph.International Pharmacopoeia R&DResearch and development TBTuberculosis USPUnited States Pharmacopeia 25ºC/60%RH25ºC ± 2ºC / 60% RH ± 5% RH etc.

3 TG Dekker – WHO, MalaysiaFeb 2005 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 and  when correctly distributed, stored & handled

4 TG Dekker – WHO, MalaysiaFeb 2005 Topics for discussion 1.Objective of stability studies 2.Glossary / definitions 3.Example of transport monitoring 4.Study protocol/requirements 5.Rifampicin containing FDCs to exemplify  Expression of degradants  Assay / degradation analytical requirements 6.Closing remarks

5 TG Dekker – WHO, MalaysiaFeb 2005 The objective of stability studies The purpose of stability testing is to provide evidence on how the quality of a drug substance [API] or drug product [FPP]  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 (drug substance) or  a shelf life for the FPP (drug product) and recommended storage conditions. ICH QA1(R2)

6 TG Dekker – WHO, MalaysiaFeb 2005 Glossary [ICH QA1(R2)] Re-test period  The period of time during which the API is expected to remain within its specification and, therefore, can be used in the manufacture of a given drug product, provided that the API has been stored under the defined conditions  After this period, a batch of API destined for use in the manufacture of a FPP should be re-tested for compliance with the specification and then used immediately  A batch of drug substance can be re-tested multiple times and a different portion of the batch used after each re-test, as long as it continues to comply with the specification  For most biotechnological/biological substances known to be labile, it is more appropriate to establish a shelf life than a re- test period. The same may be true for certain antibiotics

7 TG Dekker – WHO, MalaysiaFeb 2005 Glossary (2) Re-test date The date after which samples of the API should be examined to ensure that the material is still in compliance with the specification and thus suitable for use in the manufacture of a given drug product [if stored under defined conditions] Expiry (expiration) date The date placed on the container label of an FPP designating the time prior to which a batch of the FPP is expected to remain within the approved shelf life specification  if stored under defined conditions, and after which it must not be used {no re-testing !!}

8 TG Dekker – WHO, MalaysiaFeb 2005 Glossary (3) Stress testing (API)  Studies undertaken to elucidate the intrinsic stability of the IPA. Such testing is part of the development strategy and is normally carried out under more severe conditions than those used for accelerated testing. Stress testing (finished product)  Studies undertaken to assess the effect of severe conditions on the finished product. Such studies include photostability testing (see ICH Q1B) and specific testing on certain products, (e.g., metered dose inhalers, creams, emulsions, refrigerated aqueous liquid products).

9 TG Dekker – WHO, MalaysiaFeb 2005 Glossary (4) Accelerated testing  Studies designed to increase the rate of chemical degradation or physical change of an API or FPP by using exaggerated storage conditions as part of the formal stability studies. Data from these studies, in addition to long term stability studies, can be used  to assess longer term chemical effects at non-accelerated (real-time) conditions &  to evaluate the effect of short term excursions outside the label storage conditions such as might occur during shipping  Results from accelerated testing studies are not always predictive of physical changes Current accelerated conditions for solid orals: 40ºC/75%RH

10 TG Dekker – WHO, MalaysiaFeb 2005 Example of shipping conditions (1) UNICEF ↔ Kampala (1989): Temperature

11 TG Dekker – WHO, MalaysiaFeb 2005 Example of shipping conditions (2) UNICEF ↔ Kampala (1989): Relative humidity

12 TG Dekker – WHO, MalaysiaFeb 2005 Stability protocol/report The following elements (see Guidelines, Annex 2) 1.Info on batches tested (commercial formula) 2.Unit composition (or cross-reference) 3.Container-closure system (commercial!!) 4.Literature and/or supporting data 5.Stability specifications (only for FPPs) 6.Analytical methods – stability indicating (cross-reference) 7.Stability plan (schedule) 8.Tabulated test results (including specifications) 9.Analysis/discussion of data (statistical if negative trend) 10.Re-test or shelf-life proposal (including storage condition) 11.Post approval commitments

13 TG Dekker – WHO, MalaysiaFeb 2005 Stability batches  Stability data for three primary batches  The formulation and manufacturing process should be the same as proposed for marketing  In container-closure system proposed for marketing  Preferably manufactured from different API batches  Full info on batches tested (tabulated format) e.g.:  Batch number  Manufacturing date  Manufacturing site  Batch size (in kg & in number of units)  Container-closure (primary packaging)  Date of initial analysis (release)  API batch number

14 TG Dekker – WHO, MalaysiaFeb 2005 Tablets – stability batches data - example 1 st 2 nd 3 rd Batch number Manufacturing date Manufacturing site Batch size (kg) Batch size (number of units) Batch type (full-scale, pilot, etc.) Primary packaging Date initial analysis Batch number of API

15 TG Dekker – WHO, MalaysiaFeb 2005 Stability specifications Stability studies should include testing of those attributes (parameters) of the FPP that are  susceptible to change during storage and thus  are likely to influence quality, safety, and/or efficacy.  The testing should cover, as appropriate, the physical, chemical, biological, and microbiological attributes, preservative content (e.g., antioxidant, antimicrobial preservative), and functionality tests (e.g., for a dose delivery system) From ICH Q1A(R2)

16 TG Dekker – WHO, MalaysiaFeb 2005 Tablets – stability specifications  Parameters for tablets that are often omitted:  Tablet strength, friability and moisture can change with time – if not in release specs, include in stability – these are interrelated, also with dissolution – these are inexpensive  Microbial limit at release and end-of-shelf  Dissolution specification must be same as for release

17 TG Dekker – WHO, MalaysiaFeb 2005 Example - FPP specs – uncoated tablets AttributeRelease limitsStability limits AppearanceFull descriptionSame as release IdentificationAt least 1 method Not required for stability studies. Not regarded as variables for product. DimensionsDiameter, etc Average massw.r.t. theoretical Mass uniformityPh.Eur/USP/Int.Ph Water contentProduct specificSame as release? Tablet hardness*Product specificSame as release

18 TG Dekker – WHO, MalaysiaFeb 2005 Example of FPP specs – uncoated tabs (con.) AttributeRelease limitsStability limits Friability *≤ 1 % (normally)Same as release DissolutionSet per productSame as release DisintegrationNot required if dissolution is done Related subs. (degradants) Only if formed during production Required. Limits to one decimal Assay (content) %, unless justified May be % if justified Microbial limitsSkip-testingEnd-of-shelf * Tests not necessary at release if done in-process

19 TG Dekker – WHO, MalaysiaFeb 2005 FPP stability specs. – special for FDCs  Degradants (related substances) must be stated & calculated in % with respect to the parent API, not the sum of the APIs, e.g.  Rifampicin / isoniazid tablets. Rifampicin quinone (degradant) as % of rifampicin (not of all peaks in HPLC)  If 2 APIs react with each other, then the degradant to be stated with respect to worst case, e.g.  Rifampicin / isoniazid tablets. Isonicotinyl hydrazone forms from the 2 APIs. Specification: % hydrazone with respect to rifampicin (worst-case in mass balance).  Unknown degradants – with respect to worst case  Dissolution – include all APIs (e.g. FDCs in the USP)

20 TG Dekker – WHO, MalaysiaFeb 2005 Isonicotinyl hydrazone expression The reaction (simplified): Isoniazid + rifampicin → hydrazone +.. Rel. MM MM Ratio (÷137) 1.0 mg 6.0 mg6.2 mg FDC mg 75 mg 150 mg FDC ratio 1.0 mg 2.0 mg  At 100% reaction, no rifampicin left, 67% isoniazid intact  Hydrazone to be expressed with respect to rifampicin  Rifampicin worst-case in mass balance

21 TG Dekker – WHO, MalaysiaFeb 2005 Stability indicating analytical methods  Analytical methods must be suitable for the purpose of stability testing (stability indicating), particularly in the case of  Assay of the API(s) in the FPP  Determination of the degradants (related substances)  Determination of preservatives  If the same as release testing methods, a reference will suffice  Release methods should include validation for stability  Compendial methods  May not be suitable (e.g. non-specific like titration)  May not exist for the particular purpose (e.g. degradants)

22 TG Dekker – WHO, MalaysiaFeb 2005 Rifampicin containing FDC assay/degradation methods (1) Particular degradants to consider: 1.Isonicotinyl hydrazone 2.Rifampicin quinone 3.Rifampicin N-oxide 4.3-Formyl rifamycin (present in FDCs?) 5.25-Desacetyl rifampicin  All to be determined & expressed with respect to rifampicin  Assay method(s) must be specific (considering degradants)  A method for degradants to be developed

23 TG Dekker – WHO, MalaysiaFeb 2005 Rifampicin containing FDC assay/degradation methods (2) Examples of methods:  USP 28 (2, 3, 4 FDC capsules/tablets)  Assay method (stability indicating when tested in our lab) C-18 column, gradient chromatography (see USP)  No specification/test for degradants  S. Singh et al. (NIPER)  Various HPLC methods, mainly related to isonicotinyl hydrazone determination, simultaneously with rifampicin and isoniazid (one example given here)  RIIP analysis (Research Institute for Industrial Pharmacy)  For assay of rifampicin and degradants – other APIs with a separate method

24 TG Dekker – WHO, MalaysiaFeb 2005 USP FDC assay method Isonicotinyl hydrazone in area of gradient “switch”, difficult for quantification switch Rifampicin Isoniazid Pyrazinamide

25 TG Dekker – WHO, MalaysiaFeb 2005 A NIPER HPLC method S. Singh et al., Pharm. Pharmacol. Commun., 6, (2000)

26 TG Dekker – WHO, MalaysiaFeb 2005 RIIP HPLC chromatogram C-18: methanol/phosphate buffer pH 7.0 : 6/4 Signals well separated rifampicin N-Oxide Hydrazone Quinone 3-Formyl rifamycin Other 3 APIs

27 TG Dekker – WHO, MalaysiaFeb FDC products – degradation results The 4FDC tablets instable: Isonicotinyl hydrazone main degradant Container permeability may play a role (Alu/Alu > Pvdc/Alu?) ProductABC Primary containerPvdc/AluHDPE securitainer Pvdc/Alu Age (months)1088 N-oxide (%) Hydrazone (%) Quinone (%) Formyl (%) Total related subs

28 TG Dekker – WHO, MalaysiaFeb 2005 Testing frequency & storage conditions Solid oral dosage forms (tablets, capsules):  Zone IV is real-time condition for prequalification project, unless otherwise justified  Zone II only if justified (may be fall-back for zone IV)  ASEAN proposal for zone IV: 30ºC / 75% RH Condition▼ Month► ºC / 65% RH (zone IV)XXXXXXXX 40ºC / 75% RH (accel) XX 25ºC / 60% RH (zone II)XXXXXXX

29 TG Dekker – WHO, MalaysiaFeb 2005 Stability storage facilities RIIP facilities (110 m 3 ) Three rooms: 25ºC/60%RH; 30ºC/65%RH; 40ºC/75%RH

30 TG Dekker – WHO, MalaysiaFeb 2005 Significant changes during stability 1.A 5% change in assay from its initial value (or failure to meet acceptance criteria when using biological methods) 2.Any degradation product exceeding its acceptance criterion 3.Failure to meet the acceptance criteria for appearance, physical attributes, and functionality test (e.g., colour, phase separation, resuspendibility, hardness, dose delivery per actuation); 4.and, as appropriate for the dosage form:  Failure to meet the acceptance criterion for pH; or  Failure to meet the acceptance criteria for dissolution for 12 dosage units 5.Dissolution specifications for release and stability must be the same (otherwise possible BE change)

31 TG Dekker – WHO, MalaysiaFeb 2005 Pitfall  The assay value is still within the limits  but the change during stability is more than 5.0%  Example  Release assay limit: 95.0 – 105.0%  Stability assay limit: 92.5 – 105.0%  Release assay: 101.0% (within spec)  24-Month assay: 93.0% (within spec)  Loss in potency: 8.0% !!  This is a significant change !!

32 TG Dekker – WHO, MalaysiaFeb 2005 Reporting of stability data  Stability should be presented in well constructed tables (stability data sheets)  See Annex 2 for an example  Relevant administrative information must appear on sheet  Acceptance criteria for each attribute must be included in the table for quick reference purposes  Result sheets must bear date and responsible person signature / QA approval

33 TG Dekker – WHO, MalaysiaFeb 2005 Evaluation of stability data 1.The data show no/little variation with time  Statistical analysis not required (justify)  Proposed shelf-life = 2 x real-time data (R), but not more than R + 12 months (30 months max) 2.The data show trend(s)  Statistical analysis required [see ICH Q1A(R2)]  Proposed shelf-life depends on the statistical analysis 3.Commitment  For confirmation of provisional (tentative) shelf-life, real- time data are required  First 3 production batches on stability  Follow up stability testing (FUST) – one batch per year

34 TG Dekker – WHO, MalaysiaFeb 2005 Closing remarks  Stability testing is an essential part of the process of ensuring that the patient receives a product that meets established standards of safety, efficacy and quality  Sound planning and execution of stability studies are important  Valuable time may be lost if the data are insufficient  Always include all attributes which may change with time (e.g. water content, friability & tablet strength in the case of uncoated tablets) – pay upfront and save later