Mock P2 for "Examplain" Hydrochloride - Draft Discussion Paper- Overall Objective

Transcription

1 Mock P2 for "Examplain" Hydrochloride - Draft Discussion Paper- Overall Objective The overall objective of this Mock P2 Draft Discussion Paper is to facilitate a scientific and regulatory dialogue between the Industry Association, EFPIA and Regulatory Authorities on the presentation of enhanced product and process understanding in regulatory dossiers, as suggested by ICH Q8 guideline, Pharmaceutical Development (Step 2) and how this could provide opportunities to develop more flexible regulatory approaches (ICH Q8). In addition, the document attempts to illustrate how the principles of Quality Risk Management as outlined in ICH Q9, Quality Risk Management (Step 2) are applied during the development process and how these principles could be presented in a P.2. section of the CTD format. The discussion paper serves as a draft of current industry thinking and to promote discussion and learning between companies, and between EFPIA and Regulatory Authority reviewers and inspectors. This document is not intended to be taken as the standard for future applications. Key Aspects This draft discussion paper attempts to illustrate the following key aspects relating to ICH Q8 and Q9 principles Enhanced Process Understanding/Quality by Design - To exemplify how modern in- or at-line analytical technologies can assist with process understanding - To illustrate the type and extent of information that would constitute other pharmaceutical development studies that lead to an enhanced knowledge of product performance (ICH Q8) - To illustrate the use of Design of Experiments (DOE) in process development - To exemplify how multivariate models can be generated and used for prediction Design Space - How it is established through scientific understanding, including use of multivariant models - How it could be represented in regulatory submissions - How it could be linked to process control strategies Quality Risk Management - Approach to risk assessment throughout the development process - Approach to risk management in the design of the control strategy - Presentation of risk management in a regulatory submission Version 3 24 Jan 06 Page 1 of 69

2 Mock P.2 Roadmap This document is not a complete P2 Pharmaceutical Development section. Some sections of the manufacturing process design are only briefly described, and some sections not described at all, which may give rise to perception of incoherence of the technical arguments in parts. The focus has been on those section which are key to the scope of the proposed discussion. The main purpose is to exemplify some fundamental principles and key concepts using a conventional, wet granulated tablet formulation of a relatively low dose, highly soluble, highly permeable (Biopharmaceutics Classification System Class I) drug substance, which has some potential for degradation. The flow of the discussion is presented in the chart (below) summarising the goals of the development (Target Product Profile) through the development process itself, generation of the proposed design space and associated control strategy, and finally proposed regulatory flexibility. Target Product Profile Definition of Product Intended Use and predefinition of Quality targets (wrt clinical relevance, efficacy and safety) An Industry View of QbD in Dossier: Key Scientific Elements and Flow Prior Knowledge Summary of Prior Scientific Knowledge (drug substance, excipients; similar formulations and processes). Initial Risk Assessment Product/ Process Dev. Overview of Quality by Design key actions and decisions taken to develop New Scientific Knowledge, e.g. DoE, PAT, Risk Assessment and Risk Control Product/ Process Design Space Summary of Scientific Understanding of Product and Process. Justification and description of Multidimensional Space that Assures Quality (interrelation-ships and boundaries of Clinical Relevance). Control Strategy Definition of Control Strategy based on Design Space leading to Control of Quality and Quality Risk Mgmt. (Process Robustness) Regulatory Flexibility Proposal of Regulatory Flexibility based on Product and Process Scientific Knowledge and Quality Risk Mgmt. (Materials, Site, Scale etc) Moisture content after fluidised bed drying has been identified as a critical attribute, and fluidised bed drying is the critical manufacturing step. Studies to produce design space for wet granulation and fluidised bed drying are described in detail. Version 3 24 Jan 06 Page 2 of 69

3 The description of other unit operations and the impact of all unit operations on some quality attributes have not been described. Additionally and deliberately not all data and risk management steps are presented. These data and records of risk management process would be available at a site for inspection if so desired. The Mock P.2 is complemented by a Mock P.3.3 excerpt outlining the process control strategy proposed for routine manufacture. It is designed based on the process understanding and risk assessment data generated during the development process. Section numbering as given in ICH M4Q, The Common Technical Document for the Registration of Pharmaceuticals for Human Use: Quality is followed as far as possible but perhaps not completely accurately. Science and Risk Based Regulatory Approach - Discussion Points ICH Q8 (step 2) outlines that demonstration of a high level of formulation and process understanding can provide for maximum regulatory flexibility in the areas of: - risk-based regulatory decisions (reviews and inspections) - manufacturing process improvements within the design space described in the dossier without further regulatory review - real time quality control, leading to a reduction of end-product release testing In this context, the EFPIA PAT Topic Group is seeking feedback and discussion on the following proposals for regulatory flexibility based on the design space, knowledge and understanding exemplified for the granulation and fluid bed drying operations in the Examplain Mock P.2: and summarized as follows: Version 3 24 Jan 06 Page 3 of 69

4 Area for Regulatory Flexibility Position Statement Rationale 1 Continuous Improvement It is proposed to make manufacturing changes within design space 2 Real Time Release (RTR) It is proposed that no conventional end product tests be performed routinely 3 Process Validation It is proposed that the conventional 3-batch validation is replaced by continuous process verification Full understanding of process and use of ICH Q8. RTR is justified based on an extended process control and monitoring scheme which includes traditional and advanced controls and has been designed based on the process understanding and application of risk assessment. Assurance is given that each process step (exemplified for granulation and drying) is routinely and reproducibly producing suitable material for the next processing step. 4 Changes to Scale and Site It is proposed that changes to scale and site be made without Authority approval, provided the process continues to operate within the design space Process understanding and risk assessment have resulted in the establishment of a design space for fluid bed drying that is transferable to and reproduced for different processing equipment, representing different processing scales, potentially on different sites, and which is linked to the routine control strategy. Version 3 24 Jan 06 Page 4 of 69

5 5 Confirmatory Stability Studies It is proposed not to conduct confirmatory stability studies: a) after changes of equipment, scale or site provided the process continues to operate within the design space b) for cgmp maintenance purposes c) after drug substance manufacturing changes, provided the drug substance has been characterized adequately and complies with the established quality criteria The proposal is based on in-depth scientific understanding of how rate of production of des-ethyl examplain is related to moisture content of tablets at time of manufacture, underpinned by knowledge of water uptake and degradation rates, control of storage of bulk product prior to packing, design of the packaging, long-term stability data on pilot batches and long term data on the first 3 production batches Instead, use of product development and process understanding knowledge, linked with risk assessment, will be used to decide what studies to conduct Developed by EFPIA Topic Group (members) Chris Potter AstraZeneca Chairman, contact details: Chris.Potter@astrazeneca.com Alastair Coupe Pfizer Rafael Beerbohm Boehringer-Ingelheim Fritz Erni Novartis Gerd Fischer Sanofi-Aventis Staffan Folestad AstraZeneca Gordon Muirhead GSK Stephan Rönninger F. Hoffman-La Roche Alistair Swanson Pfizer Version 3 24 Jan 06 Page 5 of 69

6 Table of Contents Mock P2 for "Examplain" Hydrochloride - Draft Discussion Paper Overall Objective... 1 Key Aspects... 1 Mock P.2 Roadmap... 2 Science and Risk Based Regulatory Approach - Discussion Points P.2 Pharmaceutical Development... 8 INTRODUCTION P.2.1 Components of the Drug Product P Drug Substance... 9 Salt Selection 9 Solubility 10 Solid State Properties Chemical Stability Excipient Compatibility P Excipients Mannitol 13 Microcrystalline cellulose (MCC) Povidone 14 Croscarmellose sodium Magnesium stearate P.2.2 Drug Product Initial Quality Risk Management for Examplain P Formulation Development P Overages P Physicochemical and Biological Properties Dissolution and Disintegration P.2.3 Manufacturing Process Development P Unit operations in the manufacture of examplain hydrochloride tablets P Mixing P Wet Granulation P Development of wet granulation process understanding - impact on manufacturability and dissolution and disintegration P Development of Design Space and Control Strategy for the wet granulation operation P Fluid bed drying P Summary P Quality attributes of the dried granule and impact on manufacturability and tablet quality development of process understanding Filter sock cycle P Quality attributes of the wet granulate (from the previous unit operation) P Granule water content after drying P Impact of the time course of the drying process P Development of Design Space and Control Strategy for the drying operation P Impact of process understanding for the fluid bed drying operation on the quality control of examplain hydrochloride tablets P Granulation / lubrication P Compression P Conclusion P.2.4 Container Closure System Protection 54 Compatibility 54 Safety 54 Version 3 24 Jan 06 Page 6 of 69

7 Performance 54 Design space for packaging materials P.2.5 Microbiological Attributes P.2.6 Compatibility Control Strategy as result of the quality risk management Critical to Quality Attributes (CQA) Quality Risk Management Proposed Controls Dispensing Granulation Drying Blending Tableting Impact of the control strategy to end product quality specification Dissolution Disintegration Hardness Assay and Unit Dose Uniformity Degradation Stability Conclusions: Proposal for real time release Monitoring program Continuous Improvement Scale Site Process Validation Real Time Release Reduction in Confirmatory Stability Studies Drug Substance Manufacturing Changes (only limited data given in this mock document) APPENDIX Version 3 24 Jan 06 Page 7 of 69

8 P.2 Pharmaceutical Development INTRODUCTION Examplain hydrochloride is being developed for the treatment of acute anxiety following regulatory submissions. The proposed commercial formulation for examplain hydrochloride is an uncoated immediate release tablet. A single strength (20 mg as free base) is proposed for commercialisation. Tablet formulations, of strengths 1, 10 and 20 mg, were initially developed for clinical trials. The low bulk density of the drug substance precluded a directly compressible formulation and consequently a non-complex, high shear wet granulation process followed by compression has been developed. Film coating is not required to improve subjective properties of the tablet, or to provide any additional protection of the product. Extensive development and process qualification studies have been carried out to evaluate the significance of changing process parameters on the quality and performance of the tablet formulation. These are described in detail in 3.2.P Formulation Development and 3.2.P.2.3 Manufacturing Process Development. The development of the examplain hydrochloride, 20 mg tablet and the associated manufacturing process used prior knowledge from previous products and process development projects. This comprised prior knowledge on the variability with respect to physicochemical and functional properties in all excipients used in the formulation design. In addition, complementary mechanistic understanding of the manufacturing process was obtained through application of PAT (process analytical technology) during process development. A risk analysis (Failure Mode and Effect Analysis, FMEA), in accordance with ICH Q9, was used to establish those process parameters that are likely to have the greatest impact on product quality. Appropriate multivariate experimental plans were designed based on the prior knowledge and the risk analysis. Processing experience has been gained by manufacturing three batches, at a scale of 25 kg (10% proposed commercial scale), in Tabs R Us commercial production site in Pilltown. All batches met the predetermined acceptance criteria. Data from stability studies performed in accordance with ICH guidelines show good stability of the product at intermediate and long-term storage conditions. The proposed commercial packaging for examplain hydrochloride tablets is clear Aclar UltRx 2000 unit dose blisters. Further information on the packaging is provided in 3.2.P.2.4 Container Closure System. A target product profile for an examplain hydrochloride tablet, 20 mg is given in (Table 1) Version 3 24 Jan 06 Page 8 of 69

9 Table 1. Target product profile for examplain hydrochloride tablets Description Identification Assay Degradation products Dissolution Uniformity of dosage units Microbiological limits Round normal convex uncoated tablet Positive for examplain hydrochloride 20 mg ± 5% examplain free base at time of manufacture Less than 2% des-ethyl examplain at end of shelf life Immediate release Meets pharmacopoeial acceptance criteria Meets pharmacopoeial acceptance criteria This target product profile summarises the quality attributes of the product required to meet the needs for safety and efficacy of the patient. Safety is assured primarily by ensuring that the degradation product, des-ethyl examplain, is less than 2% at the end of shelf life. This limit has been qualified in toxicological studies (reference to Safety section of application) up to a level of 10%. Additionally, application of limits for assay and uniformity of dosage units assure excess drug substance is not administered. The pharmacopoeial ranges for acceptable uniformity of content are much less than that seen for variability of plasma levels seen in patients in Phase 2 and Phase 3 clinical studies, (see Clinical section of this application). Safety is not compromised by administration of a tablet at the highest content allowed by the pharmacopoeial limit since higher doses were administered without safety findings in earlier Phase 1 and Phase 2 clinical studies. Meeting globally-agreed limits for any microbiological contamination, and application of appropriate GMP standards during manufacture assure microbiological quality of this orally administered drug. Efficacy is assured for this BCS Class I drug substance by application of a dissolution test during development. There is extensive biopharmaceutical literature, which led to the FDA Guidance for Industry- Biowaver Guidance, CDER 2000, and this work concludes that in vivo availability in patients can be assured by studying in vitro release over the physiological ph range and typically looking for equal to or greater than 85% of drug substance released in 30 minutes. Similar to the safety justification, efficacy is assured by application of a lower limit for uniformity of dosage units. 3.2.P.2.1 Components of the Drug Product 3.2.P Drug Substance <This section outlines properties of the drug substance with the potential to influence the manufacture or performance of the drug product.> Salt Selection Examplain free base and a range of salts with pharmaceutically acceptable counterions (including acetate, bromide, chloride and tartrate) were studied to determine the optimum form for development. The hydrochloride salt was selected as it is anhydrous and crystalline with a high melting point and low hygroscopicity. It is also highly water soluble, crystallised with high chemical purity and demonstrated good stability in the solid state. Version 3 24 Jan 06 Page 9 of 69

10 Solubility The aqueous solubility of examplain hydrochloride is approximately 5 mg ml -1 at 37ºC. The solubility of examplain hydrochloride has also been studied in various aqueous buffer systems across the ph range , as shown in Figure 1. As expected, due to the basic nature of examplain (pka = 10.1 in aqueous solution at 25ºC), the solubility is greatest at low ph values and begins to drop as the ph rises. Figure 1 - Solubility of examplain hydrochloride in aqueous buffers solubility (mg ml-1) solubility mg/ml ph Version 3 24 Jan 06 Page 10 of 69

11 (Figure 2) shows the ph dependence of the dose solubility volume of examplain hydrochloride, that is the volume of medium required to dissolve a unit dose (20 mga 1 ). It can be clearly seen that the unit dose is soluble in volume of much less than 250 ml across the physiological ph range, and so examplain hydrochloride can be considered a high solubility compound in the Biopharmaceutics Classification System (BCS). Figure 2 Dose solubility plot for examplain hydrochloride in aqueous buffers at 37 C 25 dose solubility (ml) Particle Size ph The influence of the particle size distribution of examplain hydrochloride on the processing attributes, homogeneity and in vitro dissolution of the tablet have been examined. Examplain hydrochloride drug substance has been produced with a wide range of particle sizes during development and scale-up. The drug substance particle size has been shown to have no significant effect on processing, granule homogeneity or tablet content uniformity (see 3.2.P.2.3 Manufacturing Process Development). Tablets manufactured from drug substance with small (d90 < 15 µm, d10 < 5 µm) and large (d90 < 180 µm, d10 < 30 µm) particles showed essentially equivalent dissolution performance (Figure 3) 1 mga = mg Active = mg expressed as free base Version 3 24 Jan 06 Page 11 of 69

12 Figure 3 - Dissolution profiles for examplain hydrochloride tablets made from drug substance with different particle size distributions (ph 6.8, 50 rpm, paddles) [DS = Drug substance] % dissolved "small" DS "large" DS Solid State Properties time (min) After extensive screening of a wide variety of solvents and conditions, only a single anhydrous solid form of examplain hydrochloride has been identified. The material is a highly crystalline, non-hygroscopic, high melting solid. Characterisation of this material is described in 3.2.S.1.3 General Properties. No evidence has been found for any hydrates or solvates of examplain hydrochloride. Due to the needle-like morphology of the examplain hydrochloride crystals, the bulk density of the solid is low (<0.2 g cm -3 ). A wet granulation process was selected to densify and promote powder flow. Examplain hydrochloride has only one polymorphic form. Chemical Stability As described in section 3.2.S.7 Stability, examplain hydrochloride drug substance exhibits good chemical stability in the solid state when protected from extremes of temperature and humidity. Under stressed conditions in aqueous solution, examplain hydrochloride undergoes hydrolytic cleavage of the ethyl ester moiety to des-ethyl examplain (Figure 4). This is also the major metabolite of examplain hydrochloride in man, and has been qualified in toxicology studies up to a level of 10%. Version 3 24 Jan 06 Page 12 of 69

13 Figure 4 Aqueous solution stability data for examplain hydrochloride showing increase of des-ethyl examplain degradation product over time Solution stability at 40 deg C % Des-ethyl examplain Excipient Compatibility Weeks Des-ethyl examplain Compatibility of examplain hydrochloride with a range of excipients suitable for wet granulation was assessed using binary mixtures under stress conditions (50ºC/20% RH and 50ºC/80% RH) for periods up to one week. No evidence was seen for degradation of drug substance in the presence of microcrystalline cellulose, mannitol, dibasic calcium phosphate, povidone K-30, hydroxypropylmethyl cellulose, croscarmellose sodium or magnesium stearate. Examplain hydrochloride was shown to be incompatible with lactose, as expected due to the ability of the primary amine in the drug substance to undergo a Maillard reaction. 3.2.P Excipients The excipients below are used to produce the proposed commercial tablet formulation: Mannitol Mannitol is added as a diluent. A concentration of 40% w/w of the excipient was selected: this level is pharmaceutically precedented. Also, development studies have shown it to provide appropriate tablet properties in combination with microcrystalline cellulose e.g. hardness, dissolution. Mannitol is non-hygroscopic at relative humidities less than 75%. Version 3 24 Jan 06 Page 13 of 69

14 Microcrystalline cellulose (MCC) MCC is added as a diluent. A concentration of 39% w/w of the excipient was selected: this level is precedented and also development studies have shown it to provide appropriate tablet properties in combination with mannitol e.g. hardness, dissolution. Povidone Povidone K-30 is added as a binder at a pharmaceutically precedented level of 5% w/w. It is added as a 25% w/w aqueous solution during granulation. Previous experience has demonstrated the suitability in essentially similar formulations. Croscarmellose sodium The croscarmellose sodium is added as a disintegrant at a pharmaceutically precedented level. A total concentration of 3% w/w is used to impart rapid disintegration. Half of the disintegrant is added intra-granularly and half added extragranularly. Magnesium stearate The magnesium stearate is used as a tablet lubricant at a level of 2% w/w. This level is higher than typical but is necessary for lubrication of this mannitol-based formulation. 3.2.P.2.2 Drug Product Initial Quality Risk Management for Examplain Based on the target product profile (Table 1), initial evaluation of physical and chemical properties of the drug substance and other components scientific knowledge prior knowledge from previous products and process development projects, the following manufacturing process (Figure 5) was suggested. Version 3 24 Jan 06 Page 14 of 69

15 Figure 5 Unit operations of the proposed Manufacturing Process The low bulk density of the drug substance and early formulation development studies led to selection of a high shear wet granulation process. The same information that has led to the proposed manufacturing process was used for an initial risk assessment. This initial assessment lead to an action plan for investigations of the formulation and the process. The risk assessment is repeated and another action plan produced leading to more studies and increased understanding, with a subsequent reduction of risks. The goal was to reduce all risks identified by formulation development and process understanding to acceptably-low levels and control any significant risks remaining with the proposed control strategy (see section 3.3). For the proposed manufacturing process for examplain hydrochloride tablets the parameters that may effect quality as described in the target product profile and the specification are evaluated in the cause and effect diagram (Ishikawa)(Figure 6) Version 3 24 Jan 06 Page 15 of 69

16 463 Figure 6 Ishikawa (fishbone) diagram for commercial manufacturing process 464 Plant Factors Drying Analytical Operator Temp Temp/RH RH Sampling Training Drug Substance Particle Size Process Conditions LOD Diluents Age Air Flow Shock Cycle Water Level Binder Temp Spray Rate Spray Pattern Method Precompression Main Compression Feeder Speed Press Speed Punch Penetration Water Content Particle Size LOD Particle Size Scrape Down Tooling Feed frame Other Lubricant Chopper Speed Mixer Speed Compression Disintegrant Binder Raw Materials Endpoint Power Time Granulation The initial risk identification was based on the evaluation of all the factors as shown in (Figure 6), prior knowledge and experience with very similar products, similar formulations and preformulation studies. This risk identification lead to a formal initial risk analysis, which is presented in (Table 2) Version 3 24 Jan 06 Page 16 of 69

17 Table 2. Initial classification of importance of unit operation to have an impact on quality Unit operations Quality attributes Dissolution Disintegration Hardness Assay Content uniformity Degradation Stability Appearance Identification Water Microbiology Influence: high low Dispensing (Raw Material Properties) Granulation Drying Prior knowledge Prior knowledge Prior Prior knowledge Prior knowledge knowledge Prior Prior knowledge Prior knowledge knowledge Prior knowledge Prior knowledge Prior Prior knowledge knowledge Prior Prior knowledge knowledge Prior knowledge Prior knowledge Prior Prior knowledge knowledge Prior knowledge Blending (Magnesium Stearate) Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Tableting Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Time elements related to storage and transportation are included as a part of the unit operation. All unit operations in (Table 2)are assessed for their importance in terms of impact on quality attributes of the finished product (essentially the target product profile).those with a possibility of having an impact on quality are coloured dark blue.those with low possibility of having an impact on quality based on the prior knowledge are coded in light blue. The goal of the development summarised in the following sections is to reduce the number of dark blue sections and control the remaining risk to an acceptable level (see Control Strategy 3.3). As a conclusion from this initial risk evaluation the following interactions and parameters require experimental investigation to define the criticality of them: - raw material variability for dissolution/disintegration and microbiology - impact of granulation on dissolution/disintegration, homogeneity and degradation - drying on content uniformity, degradation, stability, appearance, water content and microbiology - blending on content uniformity, dissolution/disintegration and hardness - tableting on dissolution/disintegration, content uniformity, hardness, assay, and appearance Packaging Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Prior knowledge Version 3 24 Jan 06 Page 17 of 69

18 Normally all these attributes and parameters would be discussed intensively in the Formulation development (see 3.2.P.2.2.1) and the Manufacturing Process Development (see 3.2.P.2.3) sections, however, for the purpose of this mock submission the unit operations of granulation and fluid bed drying are discussed in detail as they exemplify concepts for discussion. Version 3 24 Jan 06 Page 18 of 69

19 P Formulation Development The development of the proposed commercial formulation is described in this section. The qualitative and quantitative compositions of the proposed commercial formulation and the formulations used in clinical development are presented in Attachment A. In early clinical trials, tablet formulations of 1, 10 and 20mg were used but only one strength, 20mg, is proposed for commercialisation. Examplain hydrochloride is a primary amine and undergoes a Maillard reaction with lactose. Consequently, mannitol was chosen as the diluent at pharmaceutically precedented levels. The low bulk density of the drug substance precluded a directly compressible formulation and a high shear wet granulation process was developed using povidone K30 as the binder. Mannitol is well precedented as a diluent for wet granulation formulations. Microcrystalline cellulose was chosen as the other diluent as it exhibits appropriate compression properties in combination with mannitol (see Figure 7). Figure 7 Compression profiles for examplain hydrochloride tablets made at different tableting speeds Compression Force (kn) vs Crushing Strength (kp) Effect of Tablet Production Rate Crushing Strength (kp) mg Examplain 100K TPH 20mg Examplain 200K TPH (TPH = tablets per hour) Compression Force (kn) Magnesium stearate is included as the lubricant as precedented for mannitol based formulations (Handbook of Pharmaceutical Excipients p376 4 th Edition (2003), Pharmaceutical Press, edited by R C Rowe, P J Sheskey and P J Weller). In the range of 1% to 3% no significant effects on compression or dissolution at this level have been demonstrated (see Figure 8and Figure 9). Hardness above or equal 4 kp produces acceptable tablets. Version 3 24 Jan 06 Page 19 of 69

20 Figure 8 Compression profiles for examplain hydrochloride tablets made with different lubricant levels Compression Force (kn) vs Crushing Strength (kp) Effect of Lubricant Level Crushing Strength (Kp) mg Examplain 1% MgSt 20mg Examplain 2% MgSt 20mg Examplain 3% MgSt Compression Force (kn) Figure 9 Dissolution profiles for examplain hydrochloride tablets made with different lubricant levels Dissolution profiles of examplain hydrochloride tablets - effect of lubrication level ph Mean % dissolution Time (minutes) 1% Mg St 2% Mg St 3% Mg St The effects of varying excipient quantities on disintegration and dissolution for this finalised formulation were assessed by development studies, that product quality and Version 3 24 Jan 06 Page 20 of 69

21 performance is unaffected by small changes. Tablets from these studies also gave acceptable assay values and uniformity of content, and good appearance. Risk factors identified from the initial risk assessment are partially mitigated by design of the formulation, for example wet granulation assures that active ingredient homogeneity and compressibility, and the impact of raw material variability are reduced compared with a direct compression formulation and process. In conclusion, a formulation has been developed which is suitable to progress into process development, particularly examining the impact of granulation and drying on content uniformity and stability. Risks associated with the impact of all unit operations on dissolution, disintegration, hardness, assay, and appearance have been significantly reduced. Early studies were performed to examine the impact of water content on stability of this formulation. Pre-formulation stability studies have demonstrated that examplain hydrochloride undergoes hydrolytic cleavage of the ethyl ester moiety to form des-ethyl examplain (see section 3.2.P.2.1.1). Development studies have been undertaken to examine the relationship of tablet water content to stability of packaged tablets stored at 40 C/75% (Figure 10). Figure 10 Impact of tablet water content on formation of des-ethyl examplain on storage of tablets in Aclar blisters at 40ºC / 75% RH % des-ethyl examplain % 2.4% 2.8% 3.5% Initial 6w 12w 6mo These studies show that a maximum water content of 2%w/w in tablets produces acceptably stable drug product. Version 3 24 Jan 06 Page 21 of 69

22 Further preformulation studies showed that use of Aclar unit dose blisters with an aluminium foil backing improved stability compared with unpacked tablets after storage at 40 C/75% RH for 6 months (Figure 11). The batch of tablets contained 2.4% moisture content. Figure 11 Stability data for examplain hydrochloride showing the effect of packaging on increase of des-ethyl examplain over time in the formulated tablet Effect of packaging on des-ethyl examplain levels in drug product at 40C/75%RH % desethyl examplain /75 Open 40/75 Aclar Time (months) From these formulation development studies a formulation and associated primary pack have been designed and the process has been selected to provide an immediate release tablet that reduces the previously identified risk factors, e.g. dissolution and appearance. Furthermore development studies have demonstrated that water content in tablets at time of manufacture is critical for quality and requires further study during process development. Version 3 24 Jan 06 Page 22 of 69

23 P Overages There are no overages used in the manufacturing of examplain hydrochloride tablets. 3.2.P Physicochemical and Biological Properties Summary of pharmacokinetic studies: - single dose PK study - multiple dose PK study - fed-fasted PK study - 1, 10 and 20mg PK study Examplain hydrochloride is a non-hygroscopic white to off-white powder, and has a molecular weight of (the free base has a molecular weight of 500). Examplain, the free base, has a pka of 10.1 in aqueous solution at 25ºC. Examplain hydrochloride demonstrates solubility in excess of 1.0 mg ml -1 across the ph range (see section 3.2.P ). It has a high trans-membrane absorptive permeability value of 30cm/s x 10-6 per hour (stirred) in a Caco-2 model of human intestinal absorption and is rapidly absorbed following oral administration (T max is 2 hours), with oral bioavailability estimated to be 95% in man. Given the solubility, in vitro permeability and pharmacokinetic information examplain can be considered as a BCS Class 1 high solubility, high permeability compound. The absolute bioavailability of examplain hydrochloride drug product, 20 mg tablet formulation was obtained from a comparison with an intravenous formulation. In addition, a blood level study in man has shown that bioavailability achieved with the 20 mg clinical trial formulation is at least as good as that given by an oral solution. This study also demonstrated that food has no effect on bioavailability. Dissolution and Disintegration Absorption and bioavailability of examplain hydrochloride 20 mg tablet is not affected by drug dissolution as verified by the similar bioavailability for the tablet as with the oral solution. Therefore maintaining the rapid dissolution characteristics of the tablet during formulation and process development should guarantee consistent bioavailability. A dissolution test was therefore developed as an indicator of the performance of examplain hydrochloride drug product tablets and used during the formulation and process development programme. The dissolution characteristics of the examplain hydrochloride 20 mg tablet in three different dissolution media are shown in (Figure 12). Version 3 24 Jan 06 Page 23 of 69

24 Figure 12 Dissolution for Examplain hydrochloride 20 mg tablet at different ph values % dissolved M HCl ph 4.5 ph time (min) The detailed discussion to justify omission of the dissolution test from the finished product specification is given section P5.4. The compendial test was used for disintegration time in water (37 o C). The disintegration test was used throughout the development programme to monitor the performance of the examplain hydrochloride tablet manufacturing process. Details of the respective unit operations with impact on disintegration are described in 3.2.P.2.3. The details of the strategy to control disintegration and hence dissolution is described in 3.2.P.3. Conclusions from formulation development studies are: -a suitable formulation and primary package have been developed for further process development work. -a suitable dissolution test has been developed, which is an excellent surrogate for in vivo absorption. -risks associated with in vitro dissolution have been reduced to the level where consideration can be given to using disintegration as a surrogate for dissolution -water content in tablets is a critical to quality attribute and requires further study during process development -insufficient data have been generated for content uniformity, however, the formulation and process appear satisfactory to warrant extensive process development studies. Version 3 24 Jan 06 Page 24 of 69

25 P.2.3 Manufacturing Process Development From the initial risk evaluation and formulation development studies described in section 3.2.P.2.2, above, a formulation and associated wet granulation process were proposed (Appendix Table 7, Figure 5). The process consists of an initial mixing step of the drug substance, the diluents (mannitol and microcrystalline cellulose) and the intra-granular disintegrant in the high shear granulator. The blend is granulated with an aqueous solution of povidone. The wet mass is transferred to a fluid bed drier and dried to a water content between 1.5 and 2% w/w. The granules produced are then blended with the extra granular quantity of croscarmellose sodium and lubricated with the magnesium stearate. The final blend is tableted. Further studies were conducted during manufacturing process development to understand better and mitigate all identified remaining high risk factors. Detailed description is given of studies to understand and mitigate risk factors in unit operations of granulation and fluidised bed drying. In each case there is a risk assessment, action plan with development, usually DOE, studies, an assessment of the results leading to a proposed design space and then control strategy. Version 3 24 Jan 06 Page 25 of 69

26 P Unit operations in the manufacture of examplain hydrochloride tablets 3.2.P Mixing 3.2.P Wet Granulation All parameters relevant to wet granulation were identified from the Ishikawa diagram (Figure 6) and were introduced into a detailed risk assessment (FMEA), in accordance with ICH Q9, to establish those process parameters that are likely to have the greatest impact on the quality of the product and be associated with a critical to quality attribute, water content (Figure 13), and hence were incorporated in Design of Experiments (DOE) studies. Version 3 24 Jan 06 Page 26 of 69

27 732 Figure 13 Design of experiment plan for commercial manufacturing process Dispense raw materials Mix API, diluents and intra -granular disintegrant in a mixer Addition of aqueous solution of binder and wet mixing Dry granulate Mix granulate with extra granular disintegrant and lubricant DOE Mixer speed Water addition rate Mixing time Inlet Temp Air flow Inlet humidity Time Final moisture content Compress on a tableting machine The process was investigated using a series of experiments that were conducted at a development scale of 1kg using a DOE approach. During the DOE the influence of varying manufacturing parameters on the quality and processability were investigated to define critical to quality parameters. Where possible prior knowledge (from previous products and process development projects) and experimental development data were utilised to provide product and process understanding and allow appropriate multivariate experimental plans to be designed. Manufacture at 25kg scale including ICH stability lots, with in-line analytical applications in place, has demonstrated that the process is capable to work at a different scale while maintaining the required quality. More detailed descriptions of the key elements for individual unit operations are given below. 3.2.P Development of wet granulation process understanding - impact on manufacturability and dissolution and disintegration Wet granulation is performed by addition of purified water with added binder to the dry blended powders and mixing until a suitable wet mass is formed. The binder Povidone K-30 is added to a level of 5% w/w as a 25% w/w aqueous solution. Changing the binder concentration to 4% and 6% as part of formulation development Version 3 24 Jan 06 Page 27 of 69

28 studies showed no significant effect on tablet dissolution or disintegration. The formulation design work showed that the formulated tablet exhibits rapid dissolution properties. In 0.1 M HCl no difference could be observed between the drug substance, dried granules or the tablet whereas at ph 6.8 it was evident that the formulated product and the dried granules had slightly faster dissolution characteristics than the drug substance, (see Figure 14) below. This confirms the rapid dissolution properties of the examplain hydrochloride 20 mg tablet. The similar dissolution results in the two dissolution media are consistent with the FDA guidance for industry for determining drug product dissolution characteristics and dissolution profile similarity ( Waiver of in vivo bioavailability and bioequivalence studies for IR solid dosage forms based on a Biopharmaceutics Classification System (2000) ). This is further evidence that dissolution is unaffected by formulation and processing variables. Figure 14 - Comparison of dissolution characteristics at ph 6.8: Examplain 20 mg tablet, dried granules and the API (examplain hydrochloride drug) % dissolved Dried granule 20 mg tablet API time (min) Because of the high capability of the wet granulation process in the initial process design studies to improve homogeneity and compressibility, and reduce the impact of raw material variability compared with direct compression, the Design of Experiments approach was tailored to evaluate the robustness of the process with respect to key process variables as listed in (Table 3) Version 3 24 Jan 06 Page 28 of 69

29 Table 3 Key process variables for the wet granulation operation Wet granulation parameters Input material attributes Mixing speed API particle size Water addition rate Mannitol particle size Mixing time Throughout the development of the manufacturing process the dry mixing and wet granulation steps were monitored in line by power consumption, (see Figure 15) Figure 15 Key process parameters for the wet granulation operation Mixing speed Mixing time Water addition rate Dry mix Red input variables Power Wet Granulation wet mass Green derived parameters Wet granule Tablet Disintegration Blue in-line measurements A summary of the results of the wet granulation DOE studies is described below. The development DOE studies conducted by spanning out the processing conditions within a wide range show that dissolution at 15 minutes is insensitive to the conditions used for the wet granulation process, whereas granulation conditions have a small effect on disintegration, which however still remains within acceptable limits. The design space for disintegration with respect to wet granulation mixing speed and water addition rate is shown in Figure Version 3 24 Jan 06 Page 29 of 69

30 Figure 16 - Effect of wet granulation mixing speed and water addition rate on disintegration, as shown by the DOE (yellow = meets Pharmacopoeial quality requirements for an immediate release dosage form) Water addition rate Disintegration Faster Mixing speed These DOE studies also showed the relative importance of the various factors (Figure 17) on disintegration with mixing speed and water addition rate being the most important. Version 3 24 Jan 06 Page 30 of 69

31 Figure 17 - Coefficient plot from the partial least squares (PLS) model for prediction of examplain tablet disintegration from key process variables Examplain PS Mannitol PS DoE Coefficients for Disintegration Mixing Speed Water Addition Rate Wet Mixing Time Compression Force Based on the results from the DOE studies described above, a multivariate process model was derived for the purpose of confirming predictability of examplain tabletquality attributes From DOE studies the effect of processing conditions on suitable quality for introduction to the subsequent unit processing operation, fluidised bed drying was investigated. The influence of mixing speed and water addition rate on granule compression properties, tablet disintegration, granule particle size and the risk for degradation in fluid bed drying were evaluated and the results are summarised in (see Figure 18 tofigure 21), the acceptable region of water addition rate and mixer speeds being given in(figure 22). For example, in section 3.2.P , it is a requirement of the process trajectory for fluid bed drying, Figure 32 that water content of granule is in the range 17.5 to 18.5% Series1 Version 3 24 Jan 06 Page 31 of 69

32 Figure 18 Effect of water addition rate and mixer speed on disintegration (red does not meet quality requirements) Water addition rate Disintegration Faster Mixer speed Figure 19 Effect of water addition rate and mixer speed on degradation in tablet (red does not meet quality requirements) Degradation (tablet) Water addition rate Increased risk of degradation FAIL in tablet Pass 881 Mixer speed Version 3 24 Jan 06 Page 32 of 69

33 Figure 20 Effect of water addition rate and mixer speed on granule particle size (red not meet quality requirements) Fines Water addition rate Pass Higher level of fines in dried FAIL granule 884 Mixer speed 885 Version 3 24 Jan 06 Page 33 of 69