Recent Advances in Co-processed APIs and Proposals for Enabling Commercialization of These Transformative Technologies

Impact of Polymers on the Kinetics of the Solid-State Phase Transition of Piracetam Polymorphs

Metastable polymorphs of active pharmaceutical ingredients can occasionally be used to enhance bioavailability or make processing more convenient. However, the thermodynamic instability of metastable polymorphs poses a severe threat to the quality and performance of the drug products. In this study, we used hot-stage microscopy and powder X-ray diffraction to quantitatively analyze the kinetics of the solid-solid phase transition of piracetam (PCM) polymorphs in the absence and presence of several polymeric excipients. The Forms I and II of PCM are enantiotropically related polymorphs, and the transition point is 75 °C. We found that 1 wt % polymer can strongly affect the transformation rate of Form II to Form I of PCM above 75 °C. PVP K30 has the highest Tg and the strongest inhibitory effect on the transition, whereas PEG has the lowest Tg and the weakest effect on the transition. Below 75 °C, the addition of 1 wt % PEG can decrease the transformation rate from Form I to Form II of PCM by a few orders of magnitude, whereas no phase transition occurs in the presence of the other investigated polymers. The inhibitory effects of the same concentration of polymers on the kinetics of the solid-solid phase transition of piracetam polymorphs are considerably greater than those on the crystallization of PCM from the amorphous phase, especially at low temperatures. We propose that the low segmental mobility of polymers enriched between the crystalline phases can considerably inhibit the nucleation and growth of the stable form at the interface during the phase transition. Our findings deepen the current understanding of the mechanisms underlying the solid-state phase transition of polymorphic drugs in the presence of polymeric excipients, providing a promising formulation approach for stabilizing the metastable pharmaceutical polymorphs.

Development of polymer-encapsulated microparticles of a lipophilic API-IL and its lipid based formulations for enhanced solubilisation

Active Pharmaceutical Ingredient-Ionic liquids (API-ILs) have the potential to improve the bioavailability of BCS Class IV Drugs. However, the problematic physical handling properties of room temperature API-ILs have impaired clinical and commercial exploitation to date. Lipid-based formulations (LBFs) are used to improve the absorption of drugs with limited bioavailability. Nonetheless, LBFs face limitations such as low drug loading capacity and sub-par physical stability. A platform for transforming API-ILs into solid forms at high loadings via spray encapsulation with polymers has been developed and previously demonstrated for hydrophilic API-ILs. The current work demonstrates that this platform technology can be applied to a lipophilic API-IL of the BCS Class IV API, chlorpromazine, and to multi-component solutions comprising API-IL and a LBF. Furthermore, solidification of a type IIIB, liquid LBF was achieved via spray encapsulation with cellulose- and methacrylate- based polymers for the first time. The spray-encapsulated formulations had excellent physical handling properties, and successfully eluted the API-IL in aqueous media. The chlorpromazine release profiles from the API-IL, the API-IL containing LBF, and the solidified formulations, were evaluated in vitro using phosphate buffer (pH 6.8) and fasted state simulated intestinal fluid (FaSSIF). Spray-encapsulated formulations exhibited improved release profiles compared to the liquid formulations. Overall, these findings indicate that phase-separated, polymeric, solid formulations of liquid API forms represent a promising platform technology for developing oral solid dosage forms of poorly bioavailable drugs.

Regulatory Considerations for Stability Studies of Co-Processed Active Pharmaceutical Ingredient

A co-processed active pharmaceutical ingredient (CP API) is the combination of an active pharmaceutical ingredient (API) with non-active component(s). This technology has been demonstrated to offer numerous benefits, including but not limited to improved API properties and stability. The infrastructure requirements are such that the manufacture of a CP API is typically best suited for an API facility. CP API has been regulated as either an API or as a drug product intermediate (DPI). This variability in the designation has led to ambiguities on the regulatory CMC expectations in the CP API including the stability of CP API and CP API containing products which, in turn has hampered the broader application of this technology in the pharmaceutical industry. This difference in designation also resulted in challenges to the lifecycle management of the regulatory documentation for the CMC information of the CP API.This white paper represents the proposals for the regulatory requirements on stability studies related to CP API and to drug product containing CP API by the CP API Working Group (WG) of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ). Additionally, considerations and the WG's recommendations on the stability studies of CP API from different manufacturing sites or processes and post-approval changes for product containing CP API are described.

Surfactant-Polymer Complexation and Competition on Drug Nanocrystal Surfaces Control Crystallinity

Nanosizing drug crystals has emerged as a successful approach to enabling oral bioavailability, as increasing drug crystal surface area improves dissolution kinetics and effective solubility. Recently, bottom-up methods have been developed to directly assemble nanosized crystals by leveraging polymer and surfactant excipients during crystallization to control crystal size, morphology, and structure. However, while significant research has investigated how polymers and other single additives inhibit or promote crystallization in pharmaceutical systems, there is little work studying the mechanistic interactions of multiple excipients on drug crystal structure and the extent of crystallinity, which can influence formulation performance. This study explores how the structure and crystallinity of a model hydrophobic drug crystal, fenofibrate, change as a result of competitive interfacial chemisorption between common nonionic surfactants (polysorbate 80 and sorbitan monooleate) and a surface-active polymer excipient (methylcellulose). Classical molecular dynamics simulations highlight how key intermolecular interactions, including surfactant-polymer complexation and surfactant screening of the crystal surface, modify the resulting crystal structure. In parallel, experiments generating drug nanocrystals in hydrogel thin films validate that drug crystallinity increases with an increasing weight fraction of surfactant. Simulation results reveal a connection between accelerated dynamics in the bulk crystal and the experimentally measured extent of crystallinity. To our knowledge, these are the first simulations that directly characterize structural changes in a drug crystal as a result of excipient surface composition and relate the experimental extent of crystallinity to structural changes in the molecular crystal. Our approach provides a mechanistic understanding of crystallinity in nanocrystallization, which can expand the range of orally deliverable small molecule therapies.

Premix technologies for drug delivery: manufacturing, applications, and opportunities in regulatory filing

Active pharmaceutical ingredients (APIs) and excipients can be carefully combined in premix-based materials before being added to dosage forms, providing a flexible platform for the improvement of drug bioavailability, stability, and patient compliance. This is a promising and transformative approach in novel and generic product development, offering both the potential to overcome challenges in the delivery of complex APIs and viable solutions for bypassing patent hurdles in generic product filing. We discuss the different types of premixes; manufacturing technologies such as spray drying, hot melt extrusion, wet granulation, co-crystal, co-milling, co-precipitation; regulatory filing opportunities; and major bottlenecks in the use of premix materials in different aspects of pharmaceutical product development.

A Commentary on Co-Processed API as a Promising Approach to Improve Sustainability for the Pharmaceutical Industry

Pharmaceutical products represent a meaningful target for sustainability improvement and emissions reduction. It is proposed here that rethinking the standard, and often linear, approach to the synthesis of Active Pharmaceutical Ingredients (API) and subsequent formulation and drug product processing will deliver transformational sustainability opportunities. The greatest potential arguably involves API that have challenging physico-chemical properties. These can require the addition of excipients that can significantly exceed the weight of the API in the final dosage unit, require multiple manufacturing steps to achieve materials amenable to delivering final dosage units, and need highly protective packaging for final product stability. Co-processed API are defined as materials generated via addition of non-covalently bonded, non-active components during drug substance manufacturing steps, differing from salts, solvates and co-crystals. They are an impactful example of provocative re-thinking of historical regulatory and quality precedents, blurring drug substance and drug product operations, with sustainability opportunities. Successful examples utilizing co-processed API can modify properties with use of less excipient, while simultaneously reducing processing requirements by delivering material amenable to continuous manufacturing. There are also opportunities for co-processed API to reduce the need for highly protective packaging. This commentary will detail the array of sustainability impacts that can be delivered, inclusive of business, regulatory, and quality considerations, with discussion on potential routes to more comprehensively commercialize co-processed API technologies.

Orthogonal Gelations to Synthesize Core-Shell Hydrogels Loaded with Nanoemulsion-Templated Drug Nanoparticles for Versatile Oral Drug Delivery

Hydrophobic active pharmaceutical ingredients (APIs) are ubiquitous in the drug development pipeline, but their poor bioavailability often prevents their translation into drug products. Industrial processes to formulate hydrophobic APIs are expensive, difficult to optimize, and not flexible enough to incorporate customizable drug release profiles into drug products. Here, a novel, dual-responsive gelation process that exploits orthogonal thermo-responsive and ion-responsive gelations is introduced. This one-step "dual gelation" synthesizes core-shell (methylcellulose-alginate) hydrogel particles and encapsulates drug-laden nanoemulsions in the hydrogel matrices. In situ crystallization templates drug nanocrystals inside the polymeric core, while a kinetically stable amorphous solid dispersion is templated in the shell. Drug release is explored as a function of particle geometry, and programmable release is demonstrated for various therapeutic applications including delayed pulsatile release and sequential release of a model fixed-dose combination drug product of ibuprofen and fenofibrate. Independent control over drug loading between the shell and the core is demonstrated. This formulation approach is shown to be a flexible process to develop drug products with biocompatible materials, facile synthesis, and precise drug release performance. This work suggests and applies a novel method to leverage orthogonal gel chemistries to generate functional core-shell hydrogel particles.

Effect of organic acids on the solid-state polymorphic phase transformation of piracetam

Metastable polymorphs are frequently used in oral solid dosage forms to enhance the absorption of poorly water-soluble drug compounds. However, the solid phase transformation from the metastable polymorph to the thermodynamically stable polymorph during manufacturing or storage poses a major challenge for product development and quality control. Here, we report that low-content organic acids can exhibit distinct effects on the solid-state polymorphic phase transformation of piracetam (PCM), a nootropic drug used for memory enhancement. The addition of 1 mol% citric acid (CA) and tricarballylic acid (TA) can significantly inhibit the phase transformation of PCM Form I to Form II, while glutaric acid (GA) and adipic acid (AA) produce a minor effect. A molecular simulation shows that organic acid molecules can adsorb on the crystal surface of PCM Form I, thus slowing the movement of molecules from the metastable form to the stable form. Our study provides deeper insights into the mechanisms of solid-state polymorphic phase transformation of drugs in the presence of additives and facilitates opportunities for controlling the stability of metastable pharmaceuticals.

Templated Reactive Crystallization of Active Pharmaceutical Ingredient in Hydrogel Microparticles Enabling Robust Drug Product Processing

Commercialization of most promising active pharmaceutical ingredients (APIs) is impeded either by poor bioavailability or challenging physical properties leading to costly manufacture. Bioavailability of ionizable hydrophobic APIs can be enhanced by its conversion to salt form. While salt form of the API presents higher solution concentration than the non-ionized form, poor physical properties resulting from particle anisotropy or non-ideal morphology (needles) and particle size distribution not meeting dissolution rate targets can still inhibit its commercial translation. In this regard, API physical properties can be improved through addition of non-active components (excipients or carriers) during API manufacture. In this work, a facile method to perform reactive crystallization of an API salt in presence of the microporous environment of a hydrogel microparticle is presented. Specifically, the reaction between acidic antiretroviral API, raltegravir and base potassium hydroxide is performed in the presence of polyethylene glycol diacrylamide hydrogel microparticles. In this bottom-up approach, the spherical template hydrogel microparticles for the reaction lead to monodisperse composites loaded with inherently micronized raltegravir-potassium crystals, thus improving API physical properties without hampering bioavailability. Overall, this technique provides a novel approach to reactive crystallization while maintaining the API polymorph and crystallinity.

Current Trends in API Co-Processing: Spherical Crystallization and Co-Precipitation Techniques

Active Pharmaceutical Ingredients (APIs) do not always exhibit processable physical properties, which makes their processing in an industrial setup very demanding. These issues often lead to poor robustness and higher cost of the drug product. The issue can be mitigated by co-processing the APIs using suitable solvent media-based techniques to streamline pharmaceutical manufacturing operations. Some of the co-processing methods are the amalgamation of API purification and granulation steps. These techniques also exhibit adequate robustness for successful adoption by the pharmaceutical industry to manufacture high quality drug products. Spherical crystallization and co-precipitation are solvent media-based co-processing approaches that enhances the micromeritic and dissolution characteristics of problematic APIs. These methods not only improve API characteristics but also enable direct compression into tablets. These methods are economical and time-saving as they have the potential for effectively circumventing the granulation step, which can be a major source of variability in the product. This review highlights the recent advancements pertaining to these techniques to aid researchers in adopting the right co-processing method. Similarly, the possibility of scaling up the production of co-processed APIs by these techniques is discussed. The continuous manufacturability by co-processing is outlined with a short note on Process Analytical Technology (PAT) applicability in monitoring and improving the process.

Improvement of drug processability in a connected continuous crystallizer system using formulation additive

Continuous crystallization in the presence of polymer additives is a promising method to omit some drug formulation steps by improving the technological and also pharmacological properties of crystalline active ingredients. Accordingly, this study focuses on developing an additive-assisted continuous crystallization process using polyvinylpyrrolidone in a connected ultrasonicated plug flow crystallizer and an overflow mixed suspension mixed product removal (MSMPR) crystallizer system. We aimed to improve the flowability characteristics of small, columnar primary plug flow crystallizer-produced acetylsalicylic acid crystals as a model drug by promoting their agglomeration in MSMPR crystallizer with polyvinylpyrrolidone. The impact of the cooling antisolvent crystallization process parameters (temperature, polymer amount, total flow rate) on product quality and quantity was investigated. Finally, a spatially segmented antisolvent dosing method was also evaluated. The developed technology enabled the manufacture of purified, constant quality products in a short startup period, even with an 85% yield. We found that a higher polymer amount (7.5-14%) could facilitate agglomeration resulting in "good" flowability without altering the favorable dissolution characteristics of the primary particles.

A Comparison of Spray-Drying and Co-Precipitation for the Generation of Amorphous Solid Dispersions (ASDs) of Hydrochlorothiazide and Simvastatin

Co-processing of APIs, the practice of creating multi-component APIs directly in chemical processing facilities used to make drug substance, is gaining increased attention with a view to streamlining manufacturing, improving supply chain robustness and accessing enhanced product attributes in terms of stability and bioavailability. Direct co-precipitation of amorphous solid dispersions (ASDs) at the final step of chemical processing is one such example of co-processing. The purpose of this work was to investigate the application of different advanced solvent-based processing techniques - direct co-precipitation (CP) and the benchmark well-established spray-drying (SD) process - to the production of ASDs comprised of a drug with a high T_g (hydrochlorothiazide, HCTZ) or a low T_g (simvastatin, SIM) molecularly dispersed in a PVP/VA 64 or Soluplus® matrix. ASDs of the same composition were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD), modulated differential scanning calorimetry (mDSC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Both methods produced ASDs that were PXRD amorphous, with some differences, depending on the process used, in glass transition temperature and particle size distribution. Irrespective of manufacturing method used, all ASDs remained PXRD amorphous when subjected to high relative humidity conditions (75% RH, 25°C) for four weeks, although changes in the colour and physical characteristics were observed on storage for spray-dried systems with SIM and PVP/VA 64 copolymer. The particle morphology differed for co-precipitated compared to spray dried systems, with powder generated by the former process being comprised of more irregularly shaped particles of larger particle size when compared to the equivalent spray-dried systems which may enable more streamlined drug product processes to be used for CP materials. These differences may have implications in downstream drug product processing. A limitation identified when applying the solvent/anti-solvent co-precipitation method to SIM was the high antisolvent to solvent ratios required to effect the precipitation process. Thus, while similar outcomes may arise for both co-precipitation and spray drying processes in terms of ASD critical quality attributes, practical implications of applying the co-precipitation method and downstream processability of the resulting ASDs should be considered when choosing one solvent-based ASD production process over another.

Combining Isolation-Free and Co-processing Manufacturing Approaches to Access Room Temperature Ionic Liquid Forms of APIs

The addition of non-active components at the point of active pharmaceutical ingredient (API) isolation by means of co-processing is an attractive approach for improving the material properties of APIs. Simultaneously, there is increased interest in the pharmaceutical industry in continuous manufacturing processes. These often consist of liquid feeds which maintain materials in solution and mean that solids handling is avoided until the final step. Such techniques enable new forms of APIs to be used in final dosage forms which have been overlooked due to unfavourable material properties. API-based ionic liquids (API-ILs) are an example of a class of compounds that exhibit exceptional solubility and stability qualities at the cost of their physical characteristics. API-ILs could benefit from isolation-free manufacturing in combination with co-processing approaches to circumvent handling issues and make them viable routes to formulating poorly soluble APIs. However, API-ILs are most commonly synthesised via a batch reaction that produces an insoluble solid by-product. To avoid this, an ion exchange resin protocol was developed to enable the API-IL to be synthesised and purified in a single step, and also produce it in a liquid effluent that can be integrated with other unit operations. Confined agitated bed crystallisation and spray drying are examples of processes that have been adapted to produce or consume liquid feeds and were combined with the ion exchange process to incorporate the API-IL synthesis into isolation-free frameworks and continuous manufacturing streams. This combination of isolation-free and co-processing techniques paves the way towards end-to-end continuous manufacturing of API-IL drug products.

API co-crystals - Trends in CMC-related aspects of pharmaceutical development beyond solubility

Whereas pharmaceutical co-crystals are widely described as tool to improve solubility and dissolution behavior of poorly soluble drugs, so far less focus has been on their potential role to facilitate pharmaceutical manufacturability. This review summarizes recent developments in co-crystal research regarding new trends in co-crystal preparation routes and control of solid-state material attributes. Also, recent literature was reviewed to assess risks for co-crystals in formulation processes. A growing number of publications suggest that co-crystals show potential to specifically improve mechanical properties such as tabletability and compressibility, which can often be linked to intrinsic features of crystal structure properties. However, such trends must be treated with care, as molecular structures in reported co-crystal studies are not representative in some structural parameters governing also solid-state behavior (smaller molecular weight, more balanced hydrogen bond donor versus acceptor counts) compared to recent market approved small molecule drugs.

FDA/M-CERSI Co-Processed API Workshop Proceedings

These proceedings contain presentation summaries and discussion highlights from the University of Maryland Center of Excellence in Regulatory Science and Innovation (M-CERSI) Workshop on Co-processed API, held on July 13 and 14, 2022. This workshop examined recent advances in the use of co-processed active pharmaceutical ingredients as a technology to improve drug substance physicochemical properties and drug product manufacturing process robustness, and explored proposals for enabling commercialization of these transformative technologies. Regulatory considerations were discussed with a focus on the classification, CMC strategies, and CMC documentation supporting the use of this class of materials from clinical studies through commercialization. The workshop format was split between presentations from industry, academia and the FDA, followed by breakout sessions structured to facilitate discussion. Given co-processed API is a relatively new concept, the authors felt it prudent to compile these proceedings to gain further visibility to topics discussed and perspectives raised during the workshop, particularly during breakout discussions. Disclaimer: This paper reflects discussions that occurred among stakeholder groups, including FDA, on various topics. The topics covered in the paper, including recommendations, therefore, are intended to capture key discussion points. The paper should not be interpreted to reflect alignment on the different topics by the participants, and the recommendations provided should not be used in lieu of FDA published guidance or direct conversations with the Agency about a specific development program. This paper should not be construed to represent FDA's views or policies.

Improving Dissolution Performance and Drug Loading of Amorphous Dispersions Through a Hierarchical Particle Approach

Co-precipitation is an emerging manufacturing strategy for amorphous solid dispersions (ASDs). Herein, the interplay between processing conditions, surface composition, and release performance was evaluated using grazoprevir and hypromellose acetate succinate as the model drug and polymer, respectively. Co-precipitated amorphous dispersion (cPAD) particles were produced in the presence and absence of an additional polymer that was either dissolved or dispersed in the anti-solvent. This additional polymer in the anti-solvent was deposited on the surfaces of the cPAD particles during isolation and drying to create hierarchical particles, which we define here as a core ASD particle with an additional water soluble component that is coating the particle surfaces. The resultant hierarchical particles were characterized using X-ray powder diffraction, differential scanning calorimetry, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). Release performance was evaluated using a two-stage dissolution test. XPS analysis revealed a trend whereby cPAD particles with a lower surface drug concentration showed improved release relative to particles with a higher surface drug concentration, for nominally similar drug loadings. This surface drug concentration could be impacted by whether the secondary polymer was dissolved in the anti-solvent or dispersed in the anti-solvent prior to isolating final dried hierarchical cPAD powders. Grazoprevir exposure in dogs was higher when the hierarchical cPAD was dosed, with ∼1.8 fold increase in AUC compared to the binary cPAD. These observations highlight the important interplay between processing conditions and ASD performance in the context of cPAD particles and illustrate a hierarchical particle design as a successful approach to alter ASD surface chemistry to improve dissolution performance.

Microfluidic Particle Engineering of Hydrophobic Drug with Eudragit E100─Bridging the Amorphous and Crystalline Gap

Co-processing active pharmaceutical ingredients (APIs) with excipients is a promising particle engineering technique to improve the API physical properties, which can lead to more robust downstream drug product manufacturing and improved drug product attributes. Excipients provide control over critical API attributes like particle size and solid-state outcomes. Eudragit E100 is a widely used polymeric excipient to modulate drug release. Being cationic, it is primarily employed as a precipitation inhibitor to stabilize amorphous solid dispersions. In this work, we demonstrate how co-processing of E100 with naproxen (NPX) (a model hydrophobic API) into monodisperse emulsions via droplet microfluidics followed by solidification via solvent evaporation allows the facile fabrication of compact, monodisperse, and spherical particles with an expanded range of solid-state outcomes spanning from amorphous to crystalline forms. Low E100 concentrations (≤26% w/w) yield crystalline microparticles with a stable NPX polymorph distributed uniformly across the matrix at a high drug loading (∼89% w/w). Structurally, E100 incorporation reduces the size of primary particles comprising the co-processed microparticles in comparison to neat API microparticles made using the same technique and the as-received API powder. This reduction in primary particle size translates into an increased internal porosity of the co-processed microparticles, with specific surface area and pore volume ∼9 times higher than the neat API microparticles. These E100-enabled structural modifications result in faster drug release in acidic media compared to neat API microparticles. Additionally, E100-NPX microparticles have a significantly improved flowability compared to neat API microparticles and as-received API powder. Overall, this study demonstrates a facile microfluidics-based co-processing method that broadly expands the range of solid-state outcomes obtainable with E100 as an excipient, with multiscale control over the key attributes and performance of hydrophobic API-laden microparticles.

High Bulk-Density Amorphous Dispersions to Enable Direct Compression of Reduced Tablet Size Amorphous Dosage Units

Amorphous solid dispersions (ASDs) are an attractive option to improve the bioavailability of poorly water-soluble compounds. However, the material attributes of ASDs can present formulation and processability challenges, which are often mitigated by the addition of excipients albeit at the expense of tablet size. In this work, an ASD manufacturing train combining co-precipitation and thin film evaporation (TFE) was used to generate high bulk-density co-precipitated amorphous dispersion (cPAD). The cPAD/TFE material was directly compressed into tablets at amorphous solid dispersion loadings up to 89 wt%, representing a greater than 60% reduction in tablet size relative to formulated tablets containing spray dried intermediate (SDI). This high ASD loading was possible due to densification of the amorphous dispersion during drying by TFE. Pharmacokinetic performance of the TFE-isolated, co-precipitated dispersion was shown to be equivalent to an SDI formulation. These data highlight the downstream advantages of this novel ASD manufacturing pathway to facilitate reduced tablet size via high ASD loading in directly compressed tablets.

Atomic Layer Coating to Inhibit Surface Crystallization of Amorphous Pharmaceutical Powders

Preventing crystallization is a primary concern when developing amorphous drug formulations. Recently, atomic layer coatings (ALCs) of aluminum oxide demonstrated crystallization inhibition of high drug loading amorphous solid dispersions (ASDs) for over 2 years. The goal of the current study was to probe the breadth and mechanisms of this exciting finding through multiple drug/polymer model systems, as well as particle and coating attributes. The model ASD systems selected provide for a range of hygroscopicity and chemical functional groups, which may contribute to the crystallization inhibition effect of the ALC coatings. Atomic layer coating was performed to apply a 5-25 nm layer of aluminum oxide or zinc oxide onto ASD particles, which imparted enhanced micromeritic properties, namely, reduced agglomeration and improved powder flowability. ASD particles were stored at 40 °C and a selected relative humidity level between 31 and 75%. Crystallization was monitored by X-ray powder diffraction and scanning electron microscopy (SEM) up to 48 weeks. Crystallization was observable by SEM within 1-2 weeks for all uncoated samples. After ALC, crystallization was effectively delayed or completely inhibited in some systems up to 48 weeks. The delay achieved was demonstrated regardless of polymer hygroscopicity, presence or absence of hydroxyl functional groups in drugs and/or polymers, particle size, or coating properties. The crystallization inhibition effect is attributed primarily to decreased surface molecular mobility. ALC has the potential to be a scalable strategy to enhance the physical stability of ASD systems to enable high drug loading and enhanced robustness to temperature or relative humidity excursions.

Dissolution Behavior of Weakly Basic Pharmaceuticals from Amorphous Dispersions Stabilized by a Poly(dimethylaminoethyl Methacrylate) Copolymer

Amorphous solid dispersions (ASDs) are a well-documented formulation approach to improve the rate and extent of dissolution for hydrophobic pharmaceuticals. However, weakly basic compounds can complicate standard approaches to ASDs due to pH-dependent solubility, resulting in uncontrolled drug release in gastric conditions and unstabilized supersaturated solutions prone to precipitation at neutral pH. This work examines the release mechanisms of amorphous dispersions containing model weakly basic pharmaceuticals posaconazole and lumefantrine from a basic poly(dimethylaminoethyl methacrylate) copolymer (Eudragit EPO) and compares their dissolution behavior with ASDs stabilized by acidic and neutral polymers to understand potential benefits to release from a basic polymeric stabilizer. It was found that dissolution of Eudragit EPO ASDs resulted in supersaturation under gastric conditions, which could be sustained upon adjustment to neutral pH. However, the dissolution behavior of Eudragit EPO ASDs was sensitive to the initial pH of the gastric media. For lumefantrine, elevated initial gastric pH resulted in precipitation of amorphous nanoparticles; for posaconazole, elevated gastric pH led to crystallization of the pharmaceutical from solution. This sensitivity to gastric pH was found to originate from the impact of Eudragit EPO on gastric pH and the solubility of each pharmaceutical in the first stage of dissolution. In total, these data illustrate benefits and liabilities for the use of Eudragit EPO for ASDs containing weak pharmaceutical bases to guide the design of robust pharmaceutical formulations.

Solution Oligonucleotide APIs: Regulatory Considerations

Manufacture of oligonucleotide active pharmaceutical ingredients (APIs) typically consists of solid-phase synthesis, deprotection and cleavage, purification and filtration, and isolation from aqueous solutions through lyophilization. In the first step of drug product manufacture, the API is dissolved in water again and excipients are added. While isolation of oligonucleotide APIs can be meaningful in many cases, there may be cases where keeping the API in solution provides benefit, and multiple technical aspects must be taken into account and balanced when determining the appropriate API form. A significant factor is whether an API in solution will contain additional components. While APIs in solution containing additional components (so-called formulated APIs) are well established for biological products, there are regulatory guidelines in place that represent hurdles for industry to using a formulated API approach for oligonucleotide drugs. The present communication outlines conditions where a formulated API approach can be chosen in compliance with existing guidelines. Relevant aspects pertaining to risk management, GMP standards, facility design, control strategies, and regulatory submission content are discussed. In addition, the authors propose that existing guidelines be modernized to enable the use of a formulated API approach for additional reasons than the ones described in the existing regulatory framework. The manuscript aims to promote a dialog with regulators in this field.

Control of Drug-Excipient Particle Attributes with Droplet Microfluidic-based Extractive Solidification Enables Improved Powder Rheology

PURPOSE

Industrial implementation of continuous oral solid dosage form manufacturing has been impeded by the poor powder flow properties of many active pharmaceutical ingredients (APIs). Microfluidic droplet-based particle synthesis is an emerging particle engineering technique that enables the production of neat or composite microparticles with precise control over key attributes that affect powder flowability, such as particle size distribution, particle morphology, composition, and the API's polymorphic form. However, the powder properties of these microparticles have not been well-studied due to the limited mass throughputs of available platforms. In this work, we produce spherical API and API-composite microparticles at high mass throughputs, enabling characterization and comparison of the bulk powder flow properties of these materials and greater understanding of how particle-scale attributes correlate with powder rheology.

METHODS

A multi-channel emulsification device and an extractive droplet-based method are harnessed to synthesize spherical API and API-excipient particles of artemether. As-received API and API crystallized in the absence of droplet confinement are used as control cases. Particle attributes are characterized for each material and correlated with a comprehensive series of powder rheology tests.

RESULTS

The droplet-based processed artemether particles are observed to be more flowable, less cohesive, and less compressible than conventionally synthesized artemether powder. Co-processing the API with polycaprolactone to produce composite microparticles reduces the friction of the powder on stainless steel, a common equipment material.

CONCLUSIONS

Droplet-based extractive solidification is an attractive particle engineering technique for improving powder processing and may aid in the implementation of continuous solid dosage form manufacturing.

Enhancing the stability of active pharmaceutical ingredients by the cocrystal strategy

Cocrystal strategies to achieve excellent physiochemical performance under different environmental stress were highlighted here. The lattice energy and the energy barrier of degradation reactions are two pillars in a stable cocrystal construction.

Recent Advances in Enhancement of Dissolution and Supersaturation of Poorly Water-Soluble Drug in Amorphous Pharmaceutical Solids: A Review

Amorphization is one of the most effective pharmaceutical approaches to enhance the dissolution and oral bioavailability of poorly water-soluble drugs. In recent years, amorphous formulations have been experiencing rapid development both in theoretical and practical application. Based on using different types of stabilizing agents, amorphous formulations can be mainly classified as polymer-based amorphous solid dispersion, coamorphous formulation, mesoporous silica-based amorphous formulation, etc. This paper summarizes recent advances in the dissolution and supersaturation of these amorphous formulations. Moreover, we also highlight the roles of stabilizing agents such as polymers, low molecular weight co-formers, and mesoporous silica. Maintaining supersaturation in solution is a key factor for the enhancement of dissolution profile and oral bioavailability, and thus, the strategies and challenges for maintaining supersaturation are also discussed. With an in-depth understanding of the inherent mechanisms of dissolution behaviors, the design of amorphous pharmaceutical formulations will become more scientific and reasonable, leading to vigorous development of commercial amorphous drug products.

Review: Continuous Manufacturing of Small Molecule Solid Oral Dosage Forms

Continuous manufacturing (CM) is defined as a process in which the input material(s) are continuously fed into and transformed, and the processed output materials are continuously removed from the system. CM can be considered as matching the FDA's so-called 'Desired State' of pharmaceutical manufacturing in the twenty-first century as discussed in their 2004 publication on 'Innovation and Continuous Improvement in Pharmaceutical Manufacturing'. Yet, focused attention on CM did not really start until 2014, and the first product manufactured by CM was only approved in 2015. This review describes some of the benefits and challenges of introducing a CM process with a particular focus on small molecule solid oral dosage forms. The review is a useful introduction for individuals wishing to learn more about CM.

Design of a Combined Modular and 3D-Printed Falling Film Solution Layer Crystallizer for Intermediate Purification in Continuous Production of Pharmaceuticals

A highly scalable combined modular and 3D-printed falling film crystallization device is developed and demonstrated herein; the device uses a small, complex, printed overflow-based film distribution part that ensures formation of a well-distributed heated liquid film around a modular, tubular residence time/crystallizer section, enabling extended residence times to be achieved. A model API (ibuprofen) and impurity (ibuprofen ethyl ester) were used as a test system in the evaluation of the novel crystallizer design. The proposed crystallizer was run using three operational configurations: batch, cyclical batch, and continuous feed, all with intermittent removal of product. Results were suitable for intermediate purification requirements, and stable operation was demonstrated over multiple cycles, indicating that this approach should be compatible with parallel semicontinuous operation for intermediate purification and solvent swap applications in the manufacture of drugs.

Hierarchical Particle Approach for Co-Precipitated Amorphous Solid Dispersions for Use in Preclinical In Vivo Studies

Amorphous solid dispersions (ASD) have become a well-established strategy to improve exposure for compounds with insufficient aqueous solubility. Of methods to generate ASDs, spray drying is a leading route due to its relative simplicity, availability of equipment, and commercial scale capacity. However, the broader industry adoption of spray drying has revealed potential limitations, including the inability to process compounds with low solubility in volatile solvents, inconsistent molecular uniformity of spray dried amorphous dispersions, variable physical properties across batches and scales, and challenges containing potent compounds. In contrast, generating ASDs via co-precipitation to yield co-precipitated amorphous dispersions (cPAD) offers solutions to many of those challenges and has been shown to achieve ASDs comparable to those manufactured via spray drying. This manuscript applies co-precipitation for early safety studies, developing a streamlined process to achieve material suitable for dosing as a suspension in conventional toxicity studies. Development targets involved achieving a rapid, safely contained process for generating ASDs with high recovery yields. Furthermore, a hierarchical particle approach was used to generate composite particles where the cPAD material is incorporated in a matrix of water-soluble excipients to allow for rapid re-dispersibility in the safety study vehicle to achieve a uniform suspension for consistent dosing. Adopting such an approach yielded a co-precipitated amorphous dispersion with comparable stability, thermal properties, and in vivo pharmacokinetics to spray dried amorphous materials of the same composition.

A Co-Processed API Approach for a Shear Sensitive Compound Affording Improved Chemical Stability and Streamlined Drug Product Processing

The physical properties of active pharmaceutical ingredients (API) are critical to both drug substance (DS) isolation and drying operations, as well as streamlined drug product (DP) processing and the quality of final dosage units. High aspect ratio, low bulk density, API 'needles' in particular are a hindrance to efficient processing, with a low probability that conventional crystallization routes can modify the challenging morphology. The compound evaluated in this manuscript demonstrated this non-ideal morphology, with the added complexity of shear sensitivity. Modest shear exposure resulted in conversion of the thermodynamically stable crystalline phase to the amorphous phase, with the amorphous phase then undergoing accelerated chemical degradation. Slow filtration during DS isolation resulted in uncontrolled and elevated amorphous levels, while subsequent DP operations including blending, densification and compression increased amorphous content still further. A chemically stable final dosage unit would ideally involve a high bulk density, free flowing API that did not require densification in order to be commercialized as an oral dosage form with direct encapsulation of a single dosage unit. Despite every effort to modify the crystallization process, the physical properties of the API could not be improved. Here, an innovative isolation strategy using a thin film evaporation (TFE) process in the presence of a water soluble polymer alleviated filtration and drying risks and consistently achieved a high bulk density, free flowing co-processed API amenable to direct encapsulation. Characterization of the engineered materials suggested the lower amorphous levels and reduced shear sensitivity were achieved by coating surfaces of the API at relatively low polymer loads. This particle engineering route blurred conventional DS/DP boundaries that not only achieved improved chemical stability but also resulted in a optimized material, with simplified and more robust processing operations for both drug substance and drug product.

Formulation of ionic liquid APIs via spray drying processes to enable conversion into single and two-phase solid forms

Ionic liquid (IL) forms of drugs are increasingly being explored to address problems presented by poorly water-soluble drugs and solid-state stability. However, before ILs of active pharmaceutical ingredients (APIs) can be routinely incorporated into oral solid dosage forms (OSDs), challenges surrounding their ease of handling and manufacture must be addressed. To this end a framework for transforming API-ILs into solid forms at high loadings based on spray encapsulation using an immiscible polymer has recently been demonstrated. The current work demonstrates that this framework can be applied to a broad range of newly synthesized low glass transition temperature (T_g) API-ILs. Furthermore, the work explores a second novel approach to solidification of API-ILs based on polymer-API-IL miscibility that, to the best of our knowledge, has not been previously demonstrated. Modulated differential scanning calorimetry (mDSC) and attenuated total reflectance Fourier transform infrared spectroscopy showed that it was possible to produce spray dried solid materials, at acceptable loadings and yields for OSD applications in the form of both two-phase phase encapsulated systems and single phase amorphous solid dispersions (ASDs). This was achieved by the appropriate selection of an API-IL insoluble polymer (ethyl cellulose) for phase separated systems, or a miscible polymer with an exceptionally high T_g (the polysaccharide, maltodextrin) for the ASDs. Both approaches successfully overcame the T_g suppression associated with room temperature ILs. This work represents the first step to understanding the fundamental critical physical attributes of these systems to facilitate a more mechanistic methodology for their design.

Phase solubility diagrams and energy surface calculations support the solubility enhancement with low hygroscopicity of Bergenin: 4-Aminobenzamide (1: 1) cocrystal

Herein, we reported a new bergenin: 4-aminobenzamide (BGN-4AM) cocrystal with significantly enhanced solubility and low hygroscopicity probed from two aspects such as phase solubility diagrams and theoretical calculations. Compared with anhydrous BGN, BGN-4AM solubilities in water and different buffer solutions (pH = 1.2, 4.5, 6.8) increase significantly. It is noted that BGN-4AM solubility in pH = 6.8 buffer solution presents 32.7 times higher than anhydrous BGN. Interestingly, BGN-4AM (0.31 ± 0.07%) showcases lower hygroscopicity than anhydrous BGN (9.31 ± 0.16%). The predicted and experimental solubilities agree with each other when considering solubility product (K_sp) and solution binding constant (K₁₁) in phase solubility diagrams, indicating the solution complexes formation occurs. Further crystal surface-water interactions and Bravais, Friedel, Donnay-Harker (BFDH) analyses based on Density Functional Theory with dispersion correction (DFT-d) methods support the enhanced solubility. The water probe demonstrates an average interaction energy of -6.48 kcal/mol on the 002 plane of BGN-4AM, and only -5.47 kcal/mol on the 011 plane of BGN monohydrate. The lower lattice energy of BGN-4AM guarantees its lower hygroscopicity than BGN monohydrate. BGN-4AM with enhanced solubility and low hygroscopicity can be a potential candidate for further formulation development.