Spray drying formulation of amorphous solid dispersions

Solvent-Assisted Secondary Drying of Spray-Dried Polymers

Purpose

The purpose of this work is to introduce solvent-assisted secondary drying, a method used to accelerate the residual solvent removal from spray dried materials. Spray-drying is used to manufacture amorphous solid dispersions, which enhance the bioavailability of active pharmaceutical ingredients (APIs) with low aqueous solubility. In the spray-drying process, API and excipients are co-dissolved in a volatile organic solvent, atomized into droplets through a nozzle, and introduced to a drying chamber containing heated nitrogen gas. The product dries rapidly to form a powder, but small amounts of residual solvent (typically, 1 to 10 wt%) remain in the product and must be removed in a secondary-drying process. For some spray-dried materials, secondary drying by traditional techniques can take days and requires balancing stability risks with process time.

Methods

Spray-dried polymers were secondary dried, comparing the results for three state-of-the-art methods that employed a jacketed, agitated-vessel dryer: (1) vacuum-only drying, (2) water-assisted drying, or (3) methanol-assisted drying. Samples of material were pulled at various time points and analyzed by gas chromatography (GC) and Karl Fischer (KF) titration to track the drying process.

Results

Model systems were chosen for which secondary drying is slow. For all cases studied, methanol-assisted drying outperformed the vacuum-only and water-assisted drying methods.

Conclusions

The observation that methanol-assisted drying is more effective than the other drying techniques is consistent with the free-volume theory of solvent diffusion in polymers.

Electronic supplementary material

The online version of this article (10.1007/s11095-020-02890-0) contains supplementary material, which is available to authorized users.

Amorphous solid dispersion dry powder for pulmonary drug delivery: Advantages and challenges

Amorphous solid dispersion (ASD) is commonly used in pharmaceutical industry. It has been mainly employed to enhance the oral bioavailability of poorly water-soluble drugs that belong to class II and IV of the biopharmaceutical classification system but has showed promise in other areas of pharmaceutical research. In this review, the potential and limitations of ASD dry powder for inhalation are discussed. ASD powder for inhalation (ASD-IP) is commonly prepared by spray drying technique. The physicochemical characteristics of ASD-IP could be tailored to achieve effective lung deposition. ASD-IP could also attain rapid dissolution behavior to achieve therapeutically effective concentration either locally or systemically before particle clearance in the lung. The key challenges of using ASD powder for inhalation include the possible chemical and/or physical instability of the amorphous phase during manufacturing and in vivo, and the moisture and temperature sensitivity of ASD-IP that affects its storage stability.

Exploring the Impact of Surfactant Type and Digestion: Highly Digestible Surfactants Improve Oral Bioavailability of Nilotinib

The scientific rationale for selection of the surfactant type during oral formulation development requires an in-depth understanding of the interplay between surfactant characteristics and biopharmaceutical factors. Currently, however, there is a lack of comprehensive knowledge of how surfactant properties, such as hydrophilic-lipophilic balance (HLB), digestibility, and fatty acid (FA) chain length, translate into in vivo performance. In the present study, the relationship between surfactant properties, in vitro characteristics, and in vivo bioavailability was systematically evaluated. An in vitro lipolysis model was used to study the digestibility of a variety of nonionic surfactants. Eight surfactants and one surfactant mixture were selected for further analysis using the model poorly water-soluble drug nilotinib. In vitro lipolysis of all nilotinib formulations was performed, followed by an in vivo pharmacokinetic evaluation in rats. The in vitro lipolysis studies showed that medium-chain FA-based surfactants were more readily digested compared to long-chain surfactants. The in vivo study demonstrated that a Tween 20 formulation significantly enhanced the absolute bioavailability of nilotinib up to 5.2-fold relative to an aqueous suspension. In general, surfactants that were highly digestible in vitro tended to display higher bioavailability of nilotinib in vivo. The bioavailability may additionally be related to the FA chain length of digestible surfactants with an improved exposure in the case of medium-chain FA-based surfactants. There was no apparent relationship between the HLB value of surfactants and the in vivo bioavailability of nilotinib. The impact of this study's findings suggests that when designing surfactant-based formulations to enhance oral bioavailability of the poorly water-soluble drug nilotinib, highly digestible, medium chain-based surfactants are preferred. Additionally, for low-permeability drugs such as nilotinib, which is subject to efflux by intestinal P-glycoprotein, the biopharmaceutical effects of surfactants merit further consideration.

Impact of structural relaxation on mechanical properties of amorphous polymers

Fusion based methods, such as hot-melt extrusion, are a common way of preparing amorphous solid dispersions. Since the amorphous glass, however, is not in a configurational equilibrium, the molecular arrangement of the obtained material can differ in dependence of the preparation conditions. Although the changes in the configuration of an amorphous material, which are commonly referred to as structural relaxation or physical aging, are well investigated, the impact on mechanical properties of amorphous solid dispersions have widely been neglected so far. The presented study investigated copovidone as a model polymer commonly used in amorphous solid dispersions and revealed that structural relaxation was already introduced into the polymer during hot-melt extrusion while its degree was cooling rate dependent. The degree of structural relaxation significantly affected the mechanical properties of copovidone as assessed by diametral compression tests, macroindentation and nanoindentation. An increase in Young's modulus and indentation hardness was observable with a higher degree of structural relaxation, which, during tablet compression, translated into tablets with significantly lower tensile strength. Furthermore, evaluation of the force-displacement curves during tablet compression revealed a decreased proportion of irreversible deformation with higher degree of structural relaxation correlating well with the increased indentation hardness during macroindentation. Thus, understanding structural relaxation and its impact on material properties is of utmost importance to assess the processability and compaction performance of amorphous solid dispersions in dependence of their preparation conditions and thermal history.

Unraveling Particle Formation: From Single Droplet Drying to Spray Drying and Electrospraying

Spray drying and electrospraying are well-established drying processes that already have proven their value in the pharmaceutical field. However, there is currently still a lack of knowledge on the fundamentals of the particle formation process, thereby hampering fast and cost-effective particle engineering. To get a better understanding of how functional particles are formed with respect to process and formulation parameters, it is indispensable to offer a comprehensive overview of critical aspects of the droplet drying and particle formation process. This review therefore closely relates single droplet drying to pharmaceutical applications. Although excellent reviews exist of the different aspects, there is, to the best of our knowledge, no single review that describes all steps that one should consider when trying to engineer a certain type of particle morphology. The findings presented in this article have strengthened the predictive value of single droplet drying for pharmaceutical drying applications like spray drying and electrospraying. Continuous follow-up of the particle formation process in single droplet drying experiments hence allows optimization of manufacturing processes and particle engineering approaches and acceleration of process development.

Improved antibacterial efficiency of inhaled thiamphenicol dry powders: Mathematical modelling of in vitro dissolution kinetic and in vitro antibacterial efficacy

Thiamphenicol (TAP) is reported to be effective against many respiratory pathogens including methicillin-resistant Staphylococcus aureus (MRSA). However, its poor solubility in water remains as one of the obstacles hindering the preparation of inhalable TAP formulations. The aim of this study was to improve the dissolution rate of TAP by micronization, and investigate whether variations in the dissolution rates of TAP would affect its in vitro antibacterial activity. Inhalable dry powders composed of TAP microcrystals (MDP) or nanocrystals (NDP) were prepared by using a wet ball milling method followed by spray drying. The morphology, solid state and in vitro dissolution of these dry powders were characterized. In vitro antibacterial activities of the inhalable TAP dry powders against a MRSA strain were evaluated. A dissolution-efficacy model relating antibacterial activity with time and dissolution rate was established via modified time-kill assays. Upon being spray dried, the volumetric mean diameters of MDP and NDP were found to be around 5 µm. Solid state analyses showed that MDP and NDP possess the same crystalline form as the raw materials. NDP exhibited faster in vitro dissolution rate as compared to MDP. The in vitro antibacterial efficiency of NDP and MDP were superior to raw TAP when the test was performed at a TAP concentration of 32 mg/L. Simulated colony forming units predictions were consistent with the result measured in the time-kill experiments with Raw TAP, MDP and NDP. This study characterized the effect of the dissolution rate of TAP dry powders on in vitro antibacterial activity against MRSA, and an enhanced antibacterial activity of TAP was observed with an increase in the dissolution rate of TAP from the dry powders at certain concentration ranges.

Hypromellose - A traditional pharmaceutical excipient with modern applications in oral and oromucosal drug delivery

Hydroxypropylmethylcellulose (HPMC), also known as Hypromellose, is a traditional pharmaceutical excipient widely exploited in oral sustained drug release matrix systems. The choice of numerous viscosity grades and molecular weights available from different manufacturers provides a great variability in its physical-chemical properties and is a basis for its broad successful application in pharmaceutical research, development, and manufacturing. The excellent mucoadhesive properties of HPMC predetermine its use in oromucosal delivery systems including mucoadhesive tablets and films. HPMC also possesses desirable properties for formulating amorphous solid dispersions increasing the oral bioavailability of poorly soluble drugs. Printability and electrospinnability of HPMC are promising features for its application in 3D printed drug products and nanofiber-based drug delivery systems. Nanoparticle-based formulations are extensively explored as antigen and protein carriers for the formulation of oral vaccines, and oral delivery of biologicals including insulin, respectively. HPMC, being a traditional pharmaceutical excipient, has an irreplaceable role in the development of new pharmaceutical technologies, and new drug products leading to continuous manufacturing processes, and personalized medicine. This review firstly provides information on the physical-chemical properties of HPMC and a comprehensive overview of its application in traditional oral drug formulations. Secondly, this review focuses on the application of HPMC in modern pharmaceutical technologies including spray drying, hot-melt extrusion, 3D printing, nanoprecipitation and electrospinning leading to the formulation of printlets, nanoparticle-, microparticle-, and nanofiber-based delivery systems for oral and oromucosal application. Hypromellose is an excellent excipient for formulation of classical dosage forms and advanced drug delivery systems. New methods of hypromellose processing include spray draying, hot-melt extrusion, 3D printing, and electrospinning.

Microencapsulation of luteinizing hormone-releasing hormone agonist in poly (lactic-co-glycolic acid) microspheres by spray-drying

A spray drying technique was developed to prepare injectable and biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulating a model luteinizing hormone-releasing hormone agonist (LHRHa)-based peptide, leuprolide. Various spray drying parameters were evaluated to prepare 1-month controlled release formulations with a similar composition to the commercial Lupron Depot® (LD). A single water-in-oil emulsion of aqueous leuprolide/gelatin solution in PLGA 75/25 acid capped (13 kDa Mw) dissolved in methylene chloride (DCM) was spray-dried before washing the microspheres in cold ddH2O and freeze-drying. The spray-drying microencapsulation was characterized by: particle size/distribution (span), morphology, drug/gelatin loading, encapsulation efficiency, and residual DCM and water content. Long-term release was tested over 9 weeks in PBS + 0.02% Tween 80 + 0.02% sodium azide pH 7.4 (PBST) at 37 °C. Several physical-chemical parameters were monitored simultaneously for selected formulations, including: water uptake, mass loss, dry and hydrated glass transition temperature, to help understand the related long-term release profiles and explore the underlying controlled-release mechanisms. Compared with the commercial LD microspheres, some of the in-house spray-dried microspheres presented highly similar or even improved long-term release profiles, providing viable long-acting release (LAR) alternatives to the LD. The in vitro release mechanism of the peptide was shown to be controlled either by kinetics of polymer mass loss or by a second process, hypothesized to involve peptide desorption from the polymer. These data indicate spray drying can be optimized to prepare commercially relevant PLGA microsphere formulations for delivery of peptides, including the LHRHa, leuprolide.

Improved Dissolution and Pharmacokinetics of Abiraterone through KinetiSol® Enabled Amorphous Solid Dispersions

Abiraterone is a poorly water-soluble drug. It has a high melting point and limited solubility in organic solvents, making it difficult to formulate as an amorphous solid dispersion (ASD) with conventional technologies. KinetiSol^® is a high-energy, fusion-based, solvent-free technology that can produce ASDs. The aim of this study was to evaluate the application of KinetiSol to make abiraterone ASDs. We developed binary KinetiSol ASDs (KSDs) using both polymers and oligomers. For the first time, we reported that KinetiSol can process hydroxypropyl-β-cyclodextrin (HPBCD), a low molecular-weight oligomer. Upon X-ray diffractometry and modulated differential scanning calorimetry analysis, we found the KSDs to be amorphous. In vitro dissolution analysis revealed that maximum abiraterone dissolution enhancement was achieved using a HPBCD binary KSD. However, the KSD showed significant abiraterone precipitation in fasted state simulated intestinal fluid (FaSSIF) media. Hence, hypromellose acetate succinate (HPMCAS126G) was selected as an abiraterone precipitation inhibitor and an optimized ternary KSD was developed. A pharmacokinetic study revealed that HPBCD based binary and ternary KSDs enhanced abiraterone bioavailability by 12.4-fold and 13.8-fold, respectively, compared to a generic abiraterone acetate tablet. Thus, this study is the first to demonstrate the successful production of an abiraterone ASD that exhibited enhanced dissolution and bioavailability.

Improving solubility and oral bioavailability of a novel antimalarial prodrug: comparing spray-dried dispersions with self-emulsifying drug delivery systems

To improve the solubility and oral bioavailability of a novel antimalarial agent ELQ-331(a prodrug of ELQ-300), spray-dried dispersions (SDD) and a self-emulsifying drug delivery system (SEDDS) were developed. SDD were prepared with polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus^®) polymer carrier and Aeroperl^® 300 Pharma and characterized by differential scanning calorimetry, powder X-ray diffraction. For SEDDS, solubility in oils, surfactants, and co-surfactants was determined and ternary phase diagram was constructed to show self-emulsifying area. SEDDS were characterized for spontaneous emulsification and droplet size distribution. The amorphous ELQ-331 SDD improved the solubility to 10× in fast-state simulated intestinal fluid and addition of sodium lauryl sulphate externally to SDDs further improved the solubility to ∼28.5× versus non-formulated drug. SEDDS had good self-emulsifying characteristics with small emulsion droplet sizes and narrow particle distribution. Oral pharmacokinetic studies for SDD and SEDDS formulations were performed in rats. The ELQ-331 rapidly converted to ELQ-300 soon after oral administration in rats. Exposure levels of ELQ-300 were about 1.4-fold higher (based on AUC) in SEDDS than SDD formulations. Poorly soluble drugs like ELQ-331 can be formulated using SDD or SEDDS to improve solubility and oral bioavailability.

Influence of Composition and Spray-Drying Process Parameters on Carrier-Free DPI Properties and Behaviors in the Lung: A review

Although dry powder inhalers (DPIs) have attracted great interest compared to nebulizers and metered-dose inhalers (MDIs), drug deposition in the deep lung is still insufficient to enhance therapeutic activity. Indeed, it is estimated that only 10–15% of the drug reaches the deep lung while 20% of the drug is lost in the oropharyngeal sphere and 65% is not released from the carrier. The potentiality of the powders to disperse in the air during the patient’s inhalation, the aerosolization, should be optimized. To do so, new strategies, in addition to classical lactose-carrier, have emerged. The lung deposition of carrier-free particles, mainly produced by spray drying, is higher due to non-interparticulate forces between the carrier and drug, as well as better powder uniformity and aerosolization. Moreover, the association of two or three active ingredients within the same powder seems easier. This review is focused on a new type of carrier-free particles which are characterized by a sugar-based core encompassed by a corrugated shell layer produced by spray drying. All excipients used to produce such particles are dissected and their physico-chemical properties (Péclet number, glass transition temperature) are put in relation with the lung deposition ability of powders. The importance of spray-drying parameters on powders’ properties and behaviors is also evaluated. Special attention is given to the relation between the morphology (characterized by a corrugated surface) and lung deposition performance. The understanding of the closed relation between particle material composition and spray-drying process parameters, impacting the final powder properties, could help in the development of promising DPI systems suitable for local or systemic drug delivery.

Morphological and Structural Properties of Amorphous Lactulose Studied by Scanning Electron Microscopy, Polarized Neutron Scattering, and Molecular Dynamics Simulations

Morphological and structural properties of amorphous disaccharide lactulose (C₁₂H₂₂O₁₁), obtained by four different amorphization methods (milling, quenching of the melt form, spray-drying, and freeze-drying), are investigated by scanning electron microscopy, polarized neutron scattering, and molecular dynamics simulations. While major differences on the morphology of the different amorphous samples are revealed by scanning electron microscopy images, only subtle structural differences have been found by polarized neutron scattering. Microstructure of the milled sample appears slightly different from the other amorphized materials with the presence of remaining crystalline germs which are not detected by X-ray diffraction. Quantitative phase analysis shows that these remaining crystallites are present in a ratio between 1 and 4%, and their size remains between 20 and 30 nm despite a long milling time of about 8 h. The impact of the change in tautomeric concentrations on the physical properties of lactulose in the amorphous state has been investigated from molecular dynamics simulations. It is suggested that chemical differences between lactulose tautomers could be at the origin of small structural differences detected by polarized neutron scattering.

Solid-state properties, solubility, stability and dissolution behaviour of co-amorphous solid dispersions of baicalin

Formation of different baicalin co-former based solid dispersion formulations, which demonstrate improved solubility and dissolution performance.

Encapsulation of poorly soluble drugs in yeast glucan particles by spray drying improves dispersion and dissolution properties

In this work, novel amorphous solid dispersions based on yeast glucan particles were produced. Yeast glucan particles are hollow and porous, and they are mainly composed of amorphous polysaccharides. We hypothesized that these particles are suitable candidates for the amorphization of drugs with low water solubility. Model drugs ibuprofen and curcumin were successfully encapsulated in glucan particles by spray drying. Different spray-drying parameters were tested to evaluate the influence of atomizing droplet size and initial solid content on encapsulation efficiency. It was shown that higher solid content and, more significantly, larger droplet sizes lead to higher encapsulation efficiencies. The encapsulation efficiency of ibuprofen (10 wt%) into glucan particles was considerably improved from 41.3 ± 0.5% to 64.3 ± 0.2% by increasing initial solid content and droplet size with the two-fluid nozzle. The spray drying process was further optimized by using the ultrasonic nozzle and it was possible to achieve complete encapsulation of ibuprofen and curcumin without any precipitation of the active compound outside of the glucan particles. Overall, it was possible to produce completely amorphous composites with outstanding wettability and dispersion properties, and with significantly faster dissolution rates when compared to the micronized crude drug.

Increased bioaffinity and anti-inflammatory activity of florfenicol nanocrystals by wet grinding method

Context: The main objective of the current study is to improve the water solubility of florfenicol (FF) and evaluate changes in its pharmacokinetics and anti-inflammatory activity.Materials and methods: Florfenicol nanocrystals (FF-NC) were prepared by wet grinding combined with spray drying. The characterisations, pharmacokinetics, and anti-inflammatory activity of FF-NC were evaluated.Results: The particle size, polydispersity index (PDI), and zeta potential of FF-NC were 276.4 ± 19.4 nm, 0.166 ± 0.011, and -18.66 ± 5.25 mV, respectively. Compared with FF, FF-NC showed a better dissolution rate in media at different pH. Pharmacokinetic experiments showed the area under the curve (AUC_0-t), maximum concentration (C_max), and mean residence time (MRT) of FF-NC were about 4.62-fold, 2.86-fold, and 1.68-fold higher compared with FF, respectively. In vitro anti-inflammatory experiments showed that FF inhibited the secretion of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), and synthesis of NO in a dose-dependent manner, while FF-NC showed a stronger anti-inflammatory effect than FF under the same dose.Conclusion: FF-NC are an effective way to improve the bioaffinity and anti-inflammatory effects of FF.

Continuous Formulation Approaches of Amorphous Solid Dispersions: Significance of Powder Flow Properties and Feeding Performance

Preparation and formulation of amorphous solid dispersions (ASDs) are becoming more and more popular in the pharmaceutical field because the dissolution of poorly water-soluble drugs can be effectively improved this way, which can lead to increased bioavailability in many cases. During downstream processing of ASDs, technologists need to keep in mind both traditional challenges and the newest trends. In the last decade, the pharmaceutical industry began to display considerable interest in continuous processing, which can be explained with their potential advantages such as smaller footprint, easier scale-up, and more consistent product, better quality and quality assurance. Continuous downstream processing of drug-loaded ASDs opens new ways for automatic operation. Therefore, the formulation of poorly water-soluble drugs may be more effective and safe. However, developments can be challenging due to the poor flowability and feeding properties of ASDs. Consequently, this review pays special attention to these characteristics since the feeding of the components greatly influences the content uniformity in the final dosage form. The main purpose of this paper is to summarize the most important steps of the possible ASD-based continuous downstream processes in order to give a clear overview of current course lines and future perspectives.

Determination of Stable Co-Amorphous Drug-Drug Ratios from the Eutectic Behavior of Crystalline Physical Mixtures

Co-amorphous drug–drug systems have been developed with the overall aim of improving the physical stability of two or more amorphous drugs. Co-amorphous systems often show good physical stability, and higher solubility and dissolution rates compared to their crystalline counterparts. The aim of this study is to determine if eutectic mixtures of two drugs can form stable co-amorphous systems. Three drug–drug mixtures, indomethacin–naproxen (IND−NAP), nifedipine–paracetamol (NIF−PAR), and paracetamol–celecoxib (PAR−CCX), were investigated for their eutectic and co-amorphization behavior as well as their physical stability in the co-amorphous form. The phase diagrams of the crystalline mixtures and the thermal behavior of the co-amorphous systems were analyzed by differential scanning calorimetry. The solid-state form and physical stability of the co-amorphous systems were analyzed using X-ray powder diffractometry during storage at room temperature at dry conditions. Initial eutectic screening using nifedipine (NIF), paracetamol (PAR), and celecoxib (CCX) indicated that IND−NAP, NIF−PAR, and PAR−CCX can form eutectic mixtures. Phase diagrams were then constructed using theoretical and experimental values. These systems, at different drug-to-drug ratios, were melted and cooled to form binary mixtures. Most mixtures were found to be co-amorphous systems, as they were amorphous and exhibited a single glass transition temperature. The stability study of the co-amorphous systems indicated differences in their physical stability. Comparing the phase diagrams with the physical stability of the co-amorphous mixtures, it was evident that the respective drug–drug ratio that forms the eutectic point also forms the most stable co-amorphous system. The eutectic behavior of drug–drug systems can thus be used to predict drug ratios that form the most stable co-amorphous systems.

Harnessing the therapeutic potential of anticancer drugs through amorphous solid dispersions

The treatment of cancer is still a major challenge. But tremendous progress in anticancer drug discovery and development has occurred in the last few decades. However, this progress has resulted in few effective oncology products due to challenges associated with anticancer drug delivery. Oral administration is the most preferred route for anticancer drug delivery, but the majority of anticancer drugs currently in product pipelines and the majority of those that have been commercially approved have inherently poor water solubility, and this cannot be mitigated without compromising their potency and stability. The poor water solubility of anticancer drugs, in conjunction with other factors, leads to suboptimal pharmacokinetic performance. Thus, these drugs have limited efficacy and safety when administered orally. The amorphous solid dispersion (ASD) is a promising formulation technology that primarily enhances the aqueous solubility of poorly water-soluble drugs. In this review, we discuss the challenges associated with the oral administration of anticancer drugs and the use of ASD technology in alleviating these challenges. We emphasize the ability of ASDs to improve not only the pharmacokinetics of poorly water-soluble anticancer drugs, but also their efficacy and safety. The goal of this paper is to rationalize the application of ASD technology in the formulation of anticancer drugs, thereby creating superior oncology products that lead to improved therapeutic outcomes.

Myth or Truth: The Glass Forming Ability Class III Drugs Will Always Form Single-Phase Homogenous Amorphous Solid Dispersion Formulations

The physical stability of amorphous solid dispersions (ASD) of active pharmaceutical ingredients (APIs) of high glass forming ability (GFA class III) is generally expected to be high among the scientific community. In this study, the ASD of ten-selected class III APIs with the two polymers, PVPVA 64 and HPMC-E5, have been prepared by spray-drying, film-casting, and their amorphicity at T0 was investigated by modulated differential scanning calorimetry and powder X-ray diffraction. It was witnessed that only five out of ten APIs form good quality amorphous solid dispersions with no phase separation and zero crystalline content, immediately after the preparation and drying process. Hence, it was further established that the classification of an API as GFA class III does not guarantee the formulation of single phase amorphous solid dispersions.

Discovery of GSK3527497: A Candidate for the Inhibition of Transient Receptor Potential Vanilloid-4 (TRPV4)

GSK3527497, a preclinical candidate for the inhibition of TRPV4, was identified starting from the previously reported pyrrolidine sulfonamide TRPV4 inhibitors 1 and 2. Optimization of projected human dose was accomplished by specifically focusing on in vivo pharmacokinetic parameters CL_u, Vdss_u, and MRT. We highlight the use of conformational changes as a novel approach to modulate Vdss_u and present results that suggest that molecular-shape-dependent binding to tissue components governs Vdss_u in addition to bulk physicochemical properties. Optimization of CL_u within the series was guided by in vitro metabolite identification, and the poor FaSSIF solubility imparted by the crystalline properties of the pyrrolidine diol scaffold was improved by the introduction of a charged moiety to enable excellent exposure from high crystalline doses. GSK3527497 is a preclinical candidate suitable for oral and iv administration that is projected to inhibit TRPV4 effectively in patients from a low daily clinical dose.

Development of Thermally Conductive Polyurethane Composite by Low Filler Loading of Spherical BN/PMMA Composite Powder

The issue of electronic heat dissipation has received much attention in recent times and has become one of the key factors in electronic components such as circuit boards. Therefore, designing of materials with good thermal conductivity is vital. In this work, a thermally conductive SBP/PU composite was prepared wherein the spherical h-BN@PMMA (SBP) composite powders were dispersed in the polyurethane (PU) matrix. The thermal conductivity of SBP was found to be significantly higher than that of the pure h-BN/PU composite at the same h-BN filler loading. The SBP/PU composite can reach a high thermal conductivity of 7.3 Wm^-1 K^-1 which is twice as high as that of pure h-BN/PU composite without surface treatment in the same condition. This enhancement in the property can be attributed to the uniform dispersion of SBP in the PU polymer matrix that leads to a three-dimensional continuous heat conduction thereby improving the heat diffusion of the entire composite. Hence, we provide a valuable method for preparing a 3-dimensional heat flow path in polyurethane composite, leading to a high thermal conductivity with a small amount of filler.

A Spray-Dried Combination of Capreomycin and CPZEN-45 for Inhaled Tuberculosis Therapy

Tuberculosis (TB) remains the single most serious infectious disease attributable to a single-causative organism. A variety of drugs have been evaluated for pulmonary delivery as dry powders: capreomycin sulfate has shown efficacy and was safely delivered by inhalation at high doses to human volunteers, whereas CPZEN-45 is a new drug that has also been shown to kill resistant TB. The studies here combine these drugs-acting by different mechanisms-as components of single particles by spray-drying, yielding a new combination drug therapy. The spray-dried combination powder was prepared in an aerodynamic particle size range suitable for pulmonary delivery. Physicochemical storage stability was demonstrated for a period of 6 months. The spray-dried combination powders of capreomycin and CPZEN-45 have only moderate affinity for mucin, indicating that delivered drug will not be bound by these mucins in the lung and available for microbicidal effects. The pharmacokinetics of disposition in guinea pigs demonstrated high local concentrations of drug following direct administration to the lungs and subsequent systemic bioavailability. Further studies are required to demonstrate the in vivo efficacy of the combination to confirm the therapeutic potential of this novel combination.

Effect of Spray-Dried Particle Morphology on Mechanical and Flow Properties of Felodipine in PVP VA Amorphous Solid Dispersions

Amorphous solid dispersions (ASDs) are commonly used to enhance the oral absorption of drugs with solubility or dissolution rate limitations. Although the ASD formulation is typically constrained by physical stability and in vivo performance considerations, ASD particles can be engineered using the spray-drying process to influence mechanical and flow properties critical to tableting. Using the ASD formulation of 20% w/w felodipine dispersed in polyvinyl pyrrolidone vinyl acetate, spray-drying atomization and drying conditions were tuned to achieve 4 different powders with varying particle properties. The resulting particles ranged in volume moment mean diameter from 4 to 115 μm, bulk density from 0.05 to 0.38 g cm^-3, and morphologies of intact, collapsed, and fractured hollow spheres. Powder flowability by shear cell ranged from poor to easy flowing, whereas mechanical property tests suggested all samples will produce strong tablets at reasonable solid fractions and compression pressures. In addition, Hiestand dynamic tableting indices showed excellent dynamic bonding for 3 powders, and low viscoelasticity with high brittleness for all powders. This work demonstrates the extent spray-dried ASD particle morphologies can be engineered to achieve desired powder flow and mechanical properties to mitigate downstream processing risks and increase process throughput.

Exploring the Potential of Mesoporous Silica as a Carrier for Puerarin: Characterization, Physical Stability, and In Vivo Pharmacokinetics

The aim of this study was to evaluate the use of a novel porous silica carrier, AEROPERL^® 300 Pharma (AP), to improve the in vitro release and oral bioavailability of puerarin (PUE) in solid dispersions (SDs). PUE-AP SD formulations with different ratios of drug to silica (RDS) were prepared by the solvent method. The scanning electron microscopy (SEM) results indicated that the dispersion of PUE improved as the concentration of AP was increased. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results revealed that PUE mostly existed in an amorphous state in the SDs. The rate of drug dissolution from the SDs was significantly higher than that from the PUE powder (p < 0.05). The in vitro drug release percentage from the PUE-AP SDs increased as the RDS was reduced. The oral bioavailability of PUE from the SDs improved when using AP, as indicated by AUC_(0-∞), which was 2.05 and 2.01 times greater than that of the PUE (API) and PVP K30 SDs, respectively (p < 0.05). The drug content, in vitro release profiles, and the amorphous state of PUE in the PUE-AP SDs showed no significant changes after being stored at room temperature for 6 months or under accelerated conditions (40 ± 2°C, 75 ± 5% relative humidity) for 3 months. AP has a high pore volume, large specific surface area, excellent flowability, and hydrophilic properties, making it capable of improving the dissolution and bioavailability of poorly water-soluble drugs.

Successful oral delivery of poorly water-soluble drugs both depends on the intraluminal behavior of drugs and of appropriate advanced drug delivery systems

Poorly water-soluble drugs continue to be a problematic, yet important class of pharmaceutical compounds for treatment of a wide range of diseases. Their prevalence in discovery is still high, and their development is usually limited by our lack of a complete understanding of how the complex chemical, physiological and biochemical processes that occur between administration and absorption individually and together impact on bioavailability. This review defines the challenge presented by these drugs, outlines contemporary strategies to solve this challenge, and consequent in silico and in vitro evaluation of the delivery technologies for poorly water-soluble drugs. The next steps and unmet needs are proposed to present a roadmap for future studies for the field to consider enabling progress in delivery of poorly water-soluble compounds.

Ultraslow Cooling for the Stabilization of Pharmaceutical Glasses

Stabilization technology of glass structures is of great interest in the field of pharmaceutical science, as it may prevent poorly soluble candidate compounds from dropping out of the pipeline. Cooling rate from the melt has been recognized as one parameter to alter the energy state of the glass; however, the relationship between the physicochemical properties of glass and stabilization efficiency of the cooling rate has not been clarified yet. We have investigated the effect of cooling rate on the thermodynamic parameters of 13 pharmaceutical glasses, to find features of the compounds that are closely related to the stabilization efficiency. We have also analyzed the structural differences between slowly cooled and annealed glasses based on Fourier-transform infrared spectra and relaxation enthalpy. Although the degree of stabilization was lower for slowly cooled glasses compared to that for vapor-deposited ones, slow cooling was found to be a prominent method for producing stable glass and is applicable to bulk materials. In this observation, a strong correlation between fragility and the number of rotatable bonds was also found.

Are traditional small-scale screening methods reliable to predict pharmaceutical spray drying?

Driven by the new trend to build quality into products and reducing empiricism, small-scale screening techniques have been frequently used to evaluate, thermodynamic of drug solubility in the polymer, and drug-polymer kinetic amorphous miscibility. In this paper, these methods have been overviewed to shed light on their liabilities in predicting spray-dried amorphous solid dispersions' (ASDs) properties. By scrutinizing relevant open literature, several inconsistencies have been recognized, deemed to be due to the inability of conventional miniaturized means to simulate the spray drying process operations/constraints in formulating active pharmaceutical ingredients (APIs). Given the complex interplay of thermodynamics of mixing, heat and mass transfer, and fluid dynamics in this process, scaling rules have been introduced to remedy arisen issues in conventional miniaturized tools. Accordingly, spray drying process is analyzed considering the fundamental physical transformations involved, i.e. atomization and drying. Each transformation is explored from a scaling perspective with an emphasis on key response factors, and ways to retain them for each transformation across scales. Prospective bifurcated developments may improve the odds of successful formulations/process conditions later on during development stages.