One-step continuous extrusion process for the manufacturing of solid dispersions

Analysis of the Dissolution Mechanism of Drugs into Polymers: The Case of the PVP/Sulindac System

This paper is dealing with the dissolution mechanism of crystalline sulindac into amorphous Polyvinylpyrrolidone (PVP) upon heating and annealing at high temperatures. Special attention is paid on the diffusion mechanism of drug molecules in the polymer which leads to a homogeneous amorphous solid dispersion of the two components. The results show that isothermal dissolution proceeds through the growth of polymer zones saturated by the drug, and not by a progressive increase in the uniform drug concentration in the whole polymer matrix. The investigations also show the exceptional ability of temperature Modulated Differential Scanning Calorimetry (MDSC) to identify the equilibrium and out of equilibrium stages of dissolution corresponding to the trajectory of the mixture into its state diagram.

Continuous Manufacturing and Molecular Modeling of Pharmaceutical Amorphous Solid Dispersions

Amorphous solid dispersions enhance solubility and oral bioavailability of poorly water-soluble drugs. The escalating number of drugs with poor aqueous solubility, poor dissolution, and poor oral bioavailability is an unresolved problem that requires adequate interventions. This review article highlights recent solubility and bioavailability enhancement advances using amorphous solid dispersions (ASDs). The review also highlights the mechanism of enhanced dissolution and the challenges faced by ASD-based products, such as stability and scale-up. The role of process analytical technology (PAT) supporting continuous manufacturing is highlighted. Accurately predicting interactions between the drug and polymeric carrier requires long experimental screening methods, and this is a space where computational tools hold significant potential. Recent advancements in data science, computational tools, and easy access to high-end computation power are set to accelerate ASD-based research. Hence, particular emphasis has been given to molecular modeling techniques that can address some of the unsolved questions related to ASDs. With the advancement in PAT tools and artificial intelligence, there is an increasing interest in the continuous manufacturing of pharmaceuticals. ASDs are a suitable option for continuous manufacturing, as production of a drug product from an ASD by direct compression is a reality, where the addition of multiple excipients is easy to avoid. Significant attention is necessary for ongoing clinical studies based on ASDs, which is paving the way for the approval of many new ASDs and their introduction into the market.

Improved transdermal permeability of tanshinone IIA from cataplasms by loading onto nanocrystals and porous silica

Novel transdermal cataplasms have been designed to improve permeability of poorly soluble drugs by different pretreatments. Nanocrystal and porous silica solid dispersions were loaded with Tanshinone IIA and incorporated into a cross-linked hydrogel matrix of cataplasm. It was shown that the small particle size and improved dissolution would increase dermal bioavailability. The adhesion, rheological properties, drug release, skin permeation, skin deposition and in vivo skin absorption of the different formulations were investigated. In an in vitro experiment using mouse skin, cumulative amount of drug permeated within 24 h was 7.32 ± 0.98 μg/cm² from conventional cataplasm, 13.14 ± 0.70 μg/cm² from nanocrystal-loaded cataplasm and 11.40 ± 0.13 μg/cm² from porous silica solid dispersion-loaded cataplasm. In vitro dissolution profiles showed that drug release was 76.5% and 74.9% from two optimized cataplasms within 24 h, while conventional cataplasm was 55.0%. The cross-linking characteristics of the cataplasms were preserved after incorporation of different drug forms, while the elastic and viscous behaviors of the hydrogel layers increased. In vivo evaluation by CLSM showed the more favorable skin permeation for two optimized cataplasms. These findings suggest that applications of nanocrystal and porous silica systems on cataplasms enable effective transdermal delivery of poorly soluble drugs. The resulting drug delivery and rheological properties are desirable for transdermal application.AbbreviationAll the abbreviations that appear in this article are shown in Table 1.

Specific mechanical energy - An essential parameter in the processing of amorphous solid dispersions

Specific mechanical energy (SME) is a frequently overlooked but essential parameter of hot-melt extrusion (HME). It can determine whether an amorphous solid dispersion (ASD) can be successfully processed. A minimum combination of thermal input and SME is required to convert a crystalline active pharmaceutical product (API) into its amorphous form. A maximum combination is allowed before it or the carrier polymer chemically degrades. This has important implications on design space. SME input during HME provides information on the totality of the effect of various independent processing parameters such as screw speed, feed rate, and complex viscosity. If only these independent processing parameters are considered separately instead of SME, then important information would be lost regarding the interaction of these parameters and their ability to affect ASD formulation. A complete understanding of the HME process requires an analysis of SME. This paper provides a review of SME use in the pharmaceutical processing of ASDs, the importance of SME in terms of a variety of formulation qualities, and novel future uses of SME. Theoretical background is discussed, along with the relative importance of thermal and mechanical input on various nonsolvent ASD processing methods.

Ternary Amorphous Solid Dispersions Containing a High-Viscosity Polymer and Mesoporous Silica Enhance Dissolution Performance†

The aim of this study was to evaluate the benefits of a ternary amorphous solid dispersion (ASD) that was designed as an immediate-release tablet with a high drug load (e.g., 40% w/w) to produce heightened maintenance of drug supersaturation during dissolution testing, which will be henceforth referred to as the "maintenance ability". Ternary ASD granules were produced by hot melt extrusion (HME) and were comprised of itraconazole (ITZ) 50%, hypromellose (HPMC) 20%, and mesoporous silica (XDP) 30%, where amorphous ITZ incorporated into HPMC was efficiently absorbed in XDP pores. The ternary ASD granules containing a high-viscosity HPMC (AF4M) produced a significantly heightened maintenance ability of drug supersaturation in neutral pH dissolution media in which crystalline ITZ solubility is below 1 μg/mL. The final tablet formulation contained 80% w/w of the ASD granules (40% w/w ITZ), had an acceptable size, and exhibited both sufficient tablet hardness and disintegration. The dissolution behavior of the ternary ASD tablet exhibited a supersaturation maintenance ability similar to that of the ASD granules. Under neutral conditions, the ternary ASD tablet showed immediate and higher ITZ release compared with the binary ASD tablets, and this phenomenon could be explained by the difference in ITZ/AF4M particle size in the tablet. In high-resolution scanning electron microscopy (SEM), it was observed that ITZ and AF4M in the ternary formulation could easily form nano-sized particles (<1 μm) during the absorption process into/onto XDP pores prepared by HME, which contributed to the immediate ITZ release from the ternary ASD tablet under neutral pH conditions. Therefore, the ternary ASD containing high-viscosity HPMC and mesoporous silica prepared by HME made it possible to design a high ASD content, small-size tablet with an ideal dissolution profile in biorelevant media, and we expect that this technology can be applied for continuous HME ASD manufacturing.

Drug-Smectite Clay Amorphous Solid Dispersions Processed by Hot Melt Extrusion

The aim of this study was to introduce smectite clay matrices as a drug delivery carrier for the development of amorphous solid dispersions (ASD). Indomethacin (IND) was processed with two different smectite clays, magnesium aluminium and lithium magnesium sodium silicates, using hot melt extrusion (HME) to prepare solid dispersions. Scanning electron microscopy (SEM), powdered X-ray diffraction (PXRD), and differential scanning calorimetry (DSC) were used to examine the physical form of the drug. Energy-dispersive X-ray (EDX) spectroscopy was used to investigate the drug distribution, and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic analysis was done to detect any chemical interaction between these two kinds. Both PXRD and DSC analyses showed that drug-clay solid dispersion contained IND in amorphous form. EDX analysis showed a uniform IND dispersion in the extruded powders. ATR-FTIR data presented possible drug and clay interactions via hydrogen bonding. In vitro drug dissolution studies revealed a lag time of about 2 h in the acidic media and a rapid release of IND at pH 7.4. The work demonstrates that preparation of amorphous solid dispersion using inorganic smectite clay particles can effectively increase the dissolution rate of IND.

A Novel Approach to Optimize Hot Melt Impregnation in Terms of Amorphization Efficiency

In this study, an innovative methodology to optimize amorphization during the hot melt impregnation (HMI) process was proposed. The novelty of this report revolves around the use of thermal analysis in combination with design of experiments (DoEs) to reduce residual crystallinity during the HMI process. As a model formulation, a mixture of ibuprofen (IBU) and Neusilin was used. The main aim of the study was to identify the critical process parameters of HMI and determine their optimal values to assure a robust impregnation process and possibly the highest possible amorphization rate of IBU. In order to realize this, a DoE approach was proposed based on a face-centered composite design involving three factors. The IBU/Neusilin ratio, the feeding rate, and the screw speed were considered as variables, while the residual crystallinity level of IBU, determined using differential scanning calorimetry (DSC), was measured as the response. Additionally, the stability of IBU under HMI was analyzed using high-performance liquid chromatography to estimate the extent of potential degradation. In order to verify the correctness of the DoE model, tested extrudates were manufactured by HMI and the obtained extrudates were thoroughly examined using scanning electron micrography, X-ray powder diffraction, and DSC.

Polymorphism in Solid Dispersions

Solid dispersions embed active pharmaceutical ingredients in polymeric carriers to improve their solubility. Three solid dispersion preparation techniques are typically employed: solvent evaporation, solvent-fusion, and fusion methods. Although these are also widely recommended as preparative methods for phase diagram determination, few examples exist concerning their effect on the resulting polymorph, once the solid dispersion is produced. In this study, the influence of these methods on the polymorphic form obtained in crystalline solid dispersions (CSDs) composed of flufenamic acid (FFA) and poly(ethylene glycol) was investigated. The physical mixtures and CSDs were characterized by powder X-ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The results reveal that the fusion method leads to concomitant polymorphs (mainly FFA I and III) in the CSDs. In contrast, the solvent evaporation and solvent-fusion methods lead to FFA III. Collectively, these results demonstrate that preparative methods have a significant influence on the phase diagrams determined (average relative deviation ≤8%), which are often used to justify the design space of manufacturing processes, including those deemed "continuous." Consequently, choosing a preparation method that results in the desired polymorph is crucial to ensure accurate determination of phase diagrams and critical quality attributes of formulations.

Evaluation of Dissolution Enhancement of Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism.

Application of the combination of ball-milling and hot-melt extrusion in the development of an amorphous solid dispersion of a poorly water-soluble drug with high melting point

The aim of the study was to develop an amorphous solid dispersion of a poorly water-soluble drug with high melting point by ball milling and hot melt extrusion as a co-processing method. Solid dispersion systems were prepared by ball milling-hot melt extrusion and then compared with those prepared with hot melt extrusion. The effects of three process parameters in the co-processing method, namely, barrel temperature, screw speed, and cooling rate, were systematically studied. The physical state of prepared solid dispersion was characterized by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, phase solubility, and dissolution study. The Resveratrol-Eudragit® EPO system exhibited good miscibility and significant dissolution enhancement. Resveratrol in the amorphous solid dispersion existed in an amorphous state and had molecular interactions with Eudragit® EPO. Stability studies showed no apparent difference in the physical state of the solid dispersion after 6 months. In conclusion, combining ball milling with hot melt extrusion is a promising method for preparing the amorphous solid dispersion of a poorly water-soluble drug with high melting point.

Integrated continuous manufacturing in pharmaceutical industry: current evolutionary steps toward revolutionary future

Continuous manufacturing (CM) has the potential to provide pharmaceutical products with better quality, improved yield and with reduced cost and time. Moreover, ease of scale-up, small manufacturing footprint and on-line/in-line monitoring and control of the process are other merits for CM. Regulating authorities are supporting the adoption of CM by pharmaceutical manufacturers through issuing proper guidelines. However, implementation of this technology in pharmaceutical industry is encountered by a number of challenges regarding the process development and quality assurance. This article provides a background on the implementation of CM in pharmaceutical industry, literature survey of the most recent state-of-the-art technologies and critically discussing the encountered challenges and its future prospective in pharmaceutical industry.

Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism

Chemico-calorimetric analysis of amorphous granules manufactured via continuous granulation process

The current study explores the first case of the implementation of solution calorimetry (SolCal) in order to determine the amorphous content of crystalline benzoyl-methoxy-methylindol-acetic acid (BMA)-a model poorly soluble drug, in the amorphous granules prepared via single-step continuous twin-screw dry granulations (TSG). Amorphous magnesium aluminometasilicate (Neusilin®) (US2) was used as a novel inorganic carrier via a TwinLab 10 mm twin-screw extruder. The BMA/US2 blends were processed at 180 °C and varying drug: carrier ratios of 1:4, 1:2.5 and 1:1 (w/w). Physico-chemical characterisation conducted via SEM, DSC and XRPD showed amorphous state of the drug in all granulated formulations. Reverse optical microscopy revealed a meso-porous structure of US2 in which the drug particles are adsorbed and/or entrapped within the porous network of the carrier. This phenomenon can be the underlying reason for the increase of the amorphous content in the extruded granules. Solution calorimetry (SolCal) study revealed amorphous content of the drug in all formulations quite precisely, whereas the dynamic vapour sorption (DVS) analysis complemented the results from SolCal. Furthermore, an attempt has been made for the first time to interrelate the findings from the SolCal to that of the release of the drug from the amorphous granules. It can be concluded that SolCal can be used as a novel technique to precisely quantify and interrelate the amorphous content to its physico-chemical performances such as drug release from the granulated formulations processed via TSG.

An update on the contribution of hot-melt extrusion technology to novel drug delivery in the twenty-first century: part II

INTRODUCTION

Interest in hot-melt extrusion (HME) technology for novel applications is growing day by day, which is evident from several hundred publications within the last 5 years. HME is a cost-effective, solvent free, 'green' technology utilized for various formulations with low investment costs compared to conventional technologies. HME has also earned the attention of the pharmaceutical industry by the transformation of this technology for application in continuous manufacturing.

AREAS COVERED

Part II of the review focuses on various novel opportunities or innovations of HME such as multiple component systems (co-crystals, co-amorphous systems and salts), twin-screw granulation, semi-solids, co-extrusion, abuse deterrent formulations, solid self-emulsifying drug delivery systems, chronotherapeutic drug delivery systems, and miscellaneous applications.

EXPERT OPINION

HME is being investigated as an alternative technology for preparation of multicomponent systems such as co-crystals and co-amorphous techniques. Twin-screw granulation has gained increased interest in preparation of granules via twin-screw melt granulation or twin-screw dry granulation. This novel application of the HME process provides a promising alternate approach in the formulation of granules and solid dosage forms. However, this technology may need to be further investigated for scalability aspects of these novel applications for industrial production.

Engineering and manufacturing of pharmaceutical co-crystals: a review of solvent-free manufacturing technologies

Design and synthesis of pharmaceutical cocrystals have received great interest in recent years. Cocrystallization of drug substances offers a tremendous opportunity for the development of new drug products with superior physical and pharmacological properties such as solubility, stability, hydroscopicity, dissolution rates and bioavailability. It is now possible to engineer and develop cocrystals via 'green chemistry' and environmentally friendly approaches such as solid-state synthesis in the absence of organic solvents. In addition, significant efforts have been directed towards computational screening, cocrystal manufacturing in a continuous manner and real-time monitoring for quality purposes by using various analytical tools. Pharmaceutical cocrystals are not fully exploited yet and there is a lot of ground to cover before they can be successfully utilized as medical products.

Different effects of silica added internal or external on in vitro dissolution of indomethacin hot-melt extrudates

The purpose of this work was to investigate the effect on the dissolution behavior when silica was added in different ways. The solid dispersion was prepared by hot-melt extrusion (HME) using indomethacin (IND) as a model drug and Kollidon VA64 as a carrier. In order to change the dissolution behavior, the silica was added during or after the HME respectively, to obtain the corresponding silica internal-added solid dispersion (InSD) and silica external-added solid dispersion (ExSD). According to the results, the internal-added silicon dioxide could reduce the dissolution rate from 66.91%/h to 24.12%/h and the water infiltration rate from 0.37mm/h to 0.16mm/h in the phosphate buffer solution (PBS) of pH 6.8, so the formulation of InSD had a significant sustained release effect. But the infiltration rate of the ExSD was increased to 13.22mm/h when silica was added external, and the density of VA64 in the powder was decreased from 541.87mg/cm3 to 141.87mg/cm3, leading to a weak resistance to the external force, and the powder was easy to be dispersed after wetted by water so that the formulation of ExSD had a relatively higher dissolution rate. This phenomenon was more visible when the phosphate buffer solution was changed to pH 5.6 in which the API was more difficult to be dissolved. Accordingly, different addition ways of aerosil would change release behavior of the HME preparation.

Continuous manufacturing via hot-melt extrusion and scale up: regulatory matters

Currently, because globalization, the pharmaceutical industry is facing enormous challenges to comply with regulatory matters. Reduced patent life and overall decreased profitability of newly discovered drugs are also forcing the pharmaceutical industry to shorten the drug development time with maximum throughput. Therefore, continuous manufacturing (CM) processes via hot melt extrusion (HME) can be a promising alternative for achieving these goals. HME offers solvent-free green technology with a process that is easy to scale up. Moreover, CM provides better product quality assurance compared with batch processes, with fewer labor costs and shorter time to development. In this review, we primarily focus on various aspects of CM and the emerging application of HME to bridge the current manufacturing gap in pharmaceutical sphere.

Advanced surface chemical analysis of continuously manufactured drug loaded composite pellets

The aim of the present study was to develop and characterise polymeric composite pellets by means of continuous melt extrusion techniques. Powder blends of a steroid hormone (SH) as a model drug and either ethyl cellulose (EC N10 and EC P7 grades) or hydroxypropyl methylcellulose (HPMC AS grade) as polymeric carrier were extruded using a Pharma 11mm twin screw extruder in a continuous mode of operation to manufacture extruded composite pellets of 1mm length. Molecular modelling study using commercial Gaussian 09 software outlined a possible drug-polymer interaction in the molecular level to develop solid dispersions of the drug in the pellets. Solid-state analysis conducted via a differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray powder diffraction (XRPD) analyses revealed the amorphous state of the drug in the polymer matrices. Surface analysis using SEM/energy dispersive X-ray (EDX) of the produced pellets arguably showed a homogenous distribution of the C and O atoms in the pellet matrices. Moreover, advanced chemical surface analysis conducted via atomic force microscopy (AFM) showed a homogenous phase system having the drug molecule dispersed onto the amorphous matrices while Raman mapping confirmed the homogenous single-phase drug distribution in the manufactured composite pellets. Such composite pellets are expected to deliver multidisciplinary applications in drug delivery and medical sciences by e.g. modifying drug solubility/dissolutions or stabilizing the unstable drug (e.g. hormone, protein) in the composite network.

Amorphous solid dispersions: Rational selection of a manufacturing process

Amorphous products and particularly amorphous solid dispersions are currently one of the most exciting areas in the pharmaceutical field. This approach presents huge potential and advantageous features concerning the overall improvement of drug bioavailability. Currently, different manufacturing processes are being developed to produce amorphous solid dispersions with suitable robustness and reproducibility, ranging from solvent evaporation to melting processes. In the present paper, laboratorial and industrial scale processes were reviewed, and guidelines for a rationale selection of manufacturing processes were proposed. This would ensure an adequate development (laboratorial scale) and production according to the good manufacturing practices (GMP) (industrial scale) of amorphous solid dispersions, with further implications on the process validations and drug development pipeline.