Process monitoring and visualization solutions for hot-melt extrusion: a review

Optimizing extrusion processes and understanding conformational changes in itraconazole amorphous solid dispersions using in-line UV-Vis spectroscopy and QbD principles

This paper presents a comprehensive investigation of the manufacturing of itraconazole (ITZ) amorphous solid dispersions (ASDs) with Kolllidon® VA64 (KVA64) using hot-melt extrusion (HME) and in-line process monitoring, employing a Quality by Design (QbD) approach. A sequential Design of Experiments (DoE) strategy was utilized to optimize the manufacturing process, with in-line UV-Vis spectroscopy providing real-time monitoring. The first DoE used a fractional factorial screening design to evaluate critical process parameters (CPPs), revealing that ITZ concentration had the most significant impact on the product quality attributes. The second DoE, employing a central composite design, explored the interactions between feed rate and screw speed, using torque and absorbance at 370 nm as responses to develop a design space. Validation studies confirmed process robustness across multiple days, with stable in-line UV-Vis spectra and consistent product quality using 30 % ITZ, 300 rpm, 150 °C and 7 g/min as the optimized process conditions. Theoretical and experimental analyses indicated that shifts in UV-Vis spectra at different ITZ concentrations were due to conformational changes in ITZ, which were confirmed through density functional theory (DFT) calculations and infrared spectroscopy. This work offers novel insights into the production and monitoring of ITZ-KVA64-ASDs, demonstrating that in-line UV-Vis spectroscopy is a powerful tool for real-time process monitoring and/or control.

Strategies to improve the stability of amorphous solid dispersions in view of the hot melt extrusion (HME) method

Oral administration of drugs is preferred over other routes for several reasons: it is non-invasive, easy to administer, and easy to store. However, drug formulation for oral administration is often hindered by the drug's poor solubility, which limits its bioavailability and reduces its commercial value. As a solution, amorphous solid dispersion (ASD) was introduced as a drug formulation method that improves drug solubility by changing the molecular structure of the drugs from crystalline to amorphous. The hot melt extrusion (HME) method is emerging in the pharmaceutical industry as an alternative to manufacture ASD. However, despite solving solubility issues, ASD also exposes the drug to a high risk of crystallisation, either during processing or storage. Formulating a successful oral administration drug using ASD requires optimisation of the formulation, polymers, and HME manufacturing processes applied. This review presents some important considerations in ASD formulation, including strategies to improve the stability of the final product using HME to allow more new drugs to be formulated using this method.

Amorphous solid dispersions: Stability mechanism, design strategy and key production technique of hot melt extrusion

Solid dispersion (SD) system has been used as an effective formulation strategy to increase in vitro and in vivo performances of poorly water-soluble drugs, such as solubility/dissolution, stability and bioavailability. This review provides a comprehensive SD classification and identifies the most popular amorphous solid dispersions (ASDs). Meanwhile, this review further puts forward the systematic design strategy of satisfactory ASDs in terms of drug properties, carrier selection, preparation methods and stabilization mechanisms. In addition, hot melt extrusion (HME) as the continuous manufacturing technique is described including the principle and structure of HME instrument, key process parameters and production application, in order to guide the scale-up of ASDs and develop more ASD products to the market in pharmaceutical industry.

Review of Waterproof Breathable Membranes: Preparation, Performance and Applications in the Textile Field

Waterproof breathable membranes (WBMs) characterized by a specific internal structure, allowing air and water vapor to be transferred from one side to the other while preventing liquid water penetration, have attracted much attention from researchers. WBMs combine lamination and other technologies with textile materials to form waterproof breathable fabrics, which play a key role in outdoor sports clothing, medical clothing, military clothing, etc. Herein, a systematic overview of the recent progress of WBMs is provided, including the principles of waterproofness and breathability, common preparation methods and the applications of WBMs. Discussion starts with the waterproof and breathable mechanisms of two different membranes: hydrophilic non-porous membranes and hydrophobic microporous membranes. Then evaluation criteria and common preparation methods for WBMs are presented. In addition, treatment processes that promote water vapor transmission and prominent applications in the textile field are comprehensively analyzed. Finally, the challenges and future perspectives of WBMs are also explored.

In-line monitoring of solid dispersion preparation in small scale extrusion based on UV-vis spectroscopy

The poor solubility of a large number of active pharmaceutical ingredients (APIs) is a major challenge in pharmaceutical research. Therefore, the extrusion of amorphous solid dispersions (ASDs) is one promising approach to enhance the dissolution rate by molecularly dissolving the API in an amorphous carrier polymer. During ASD extrusion, crucial parameters as the dissolution of the API in the carrier polymer need to be monitored. Within this study, a small scale twin screw extruder was coupled with special ColVisTec UV-vis probes that are characterized by their small dimensions. This setup enables a systematic formulation design and optimization based on in-line monitoring of drug dissolution using small material quantities. In fact, sample quantities of about 5 mg were evaluated for each measurement, representing 50% of the material inside the die. The amount of undissolved drug particles was determined based on the lightness of the extrudates. It was shown that the temperature has a significant effect on the drug dissolution in the polymer. Furthermore, complete drug dissolution was shifted to lower temperatures if higher residence times were applied. Based on the courses of lightness, regime maps were modeled that specify the process conditions where ASDs are successfully manufactured.

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.

Real-time droplet size analysis using laser micrometer as a process analytical technology tool for continuous dripping process

Process analysis and monitoring during the manufacturing of the dripping pills are essential. However, research on developing sensor-based technology or process analytical technology (PAT) tools to analyze and monitor the dripping process is minimal. The purpose of this work is to develop a fast and non-destructive laser detection system for quantitative visualization of droplets, which involves detecting the size of the droplet and calculating the weight of the dripping pills during the dripping process. Several factors influencing the detection performance of the detection system and the detection system capability for quantitation of the pill weight were explored. The laser detection system accurately detects the weight of the dripping pills with the coefficients of determination (R2) higher than 0.99. It was also robust concerning the variation in critical process parameters and critical material attributes. Furthermore, the laser detection system was successfully applied to the production line of Ginkgo biloba leaf dripping pills to monitor the dripping pills weight. The proposed laser detection system can analyze and monitor the dripping process in dripping pill manufacturing with stable performance, high accuracy, and high efficiency.

On-Line Optical Monitoring of the Mixing Performance in Co-Rotating Twin-Screw Extruders

The use of real-time techniques to evaluate the global mixing performance of co-rotating twin-screw extruders is well consolidated, but much less is reported on the specific contribution of individual screw zones. This work uses on-line flow turbidity and birefringence to ascertain the mixing performance of kneading blocks with different geometries. For this purpose, one of the barrel segments of the extruder was modified in order to incorporate four sampling devices and slit dies containing optical windows were attached to them. The experiments consisted in reaching steady extrusion and then adding a small amount of tracer. Upon opening each sampling device, material was laterally detoured from the local screw channel, and its turbidity and birefringence were measured by the optical detector. Residence time distribution curves (RTD) were obtained at various axial positions along three different kneading blocks and under a range of screw speeds. It is hypothesized that K, a parameter related to the area under each RTD curve, is a good indicator of dispersive mixing, whereas variance can be used to assess distributive mixing. The experimental data confirmed that these mixing indices are sensitive to changes in processing conditions, and that they translate the expected behavior of each kneading block geometry.

Quality of FDM 3D Printed Medicines for Pediatrics: Considerations for Formulation Development, Filament Extrusion, Printing Process and Printer Design

3d printing is capable of providing dose individualization for pediatric medicines and translating the precision medicine approach into practical application. In pediatrics, dose individualization and preparation of small dosage forms is a requirement for successful therapy, which is frequently not possible due to the lack of suitable dosage forms. For precision medicine, individual characteristics of patients are considered for the selection of the best possible API in the most suitable dose with the most effective release profile to improve therapeutic outcome. 3d printing is inherently suitable for manufacturing of individualized medicines with varying dosages, sizes, release profiles and drug combinations in small batch sizes, which cannot be manufactured with traditional technologies. However, understanding of critical quality attributes and process parameters still needs to be significantly improved for this new technology. To ensure health and safety of patients, cleaning and process validation needs to be established. Additionally, adequate analytical methods for the in-process control of intermediates, regarding their printability as well as control of the final 3d printed tablets considering any risk of this new technology will be required. The PolyPrint consortium is actively working on developing novel polymers for fused deposition modeling (FDM) 3d printing, filament formulation and manufacturing development as well as optimization of the printing process, and the design of a GMP-capable FDM 3d printer. In this manuscript, the consortium shares its views on quality aspects and measures for 3d printing from drug-loaded filaments, including formulation development, the printing process, and the printed dosage forms. Additionally, engineering approaches for quality assurance during the printing process and for the final dosage form will be presented together with considerations for a GMP-capable printer design.

In-line monitoring and endpoint determination of percolation process of herbal medicine using ultraviolet spectroscopy combined with convolutional neural network

OBJECTIVES

As a common step in the herbal medicine production process, percolation usually lacks effective process monitoring methods and is often conducted with fixed process parameters. In this study, an in-line ultraviolet (UV) spectroscopy was used for monitoring the Caulis Sinomenii percolation process.

METHODS

The spectra and concentration data of 156 percolation samples from five batches were collected. Convolutional neural networks (CNNs) were used to develop quantitative calibration models. The mean squared error (MSE), mean absolute percentage error (MAPE) and mean absolute error (MAE) were compared to select the proper loss function for developing the CNN models. Meanwhile, partial least square regression (PLSR) was also used to develop calibration models for performance comparison.

KEY FINDINGS

The CNN models with MAPE or MAE as the loss function could provide accurate predictions for all samples. However, CNN models adopting MSE as the loss function tended not to predict low-concentration samples accurately. The CNN models mostly achieved satisfactory results without any preprocessing techniques and surpassed PLSR models in all the performance metrics.

CONCLUSIONS

An in-line UV spectroscopy system combining the CNN algorithm was implemented to monitor the percolation process of Caulis Sinomenii. The system can accurately determine the endpoint of the percolation process.

Machine Learning for Process Monitoring and Control of Hot-Melt Extrusion: Current State of the Art and Future Directions

In the last few decades, hot-melt extrusion (HME) has emerged as a rapidly growing technology in the pharmaceutical industry, due to its various advantages over other fabrication routes for drug delivery systems. After the introduction of the ‘quality by design’ (QbD) approach by the Food and Drug Administration (FDA), many research studies have focused on implementing process analytical technology (PAT), including near-infrared (NIR), Raman, and UV–Vis, coupled with various machine learning algorithms, to monitor and control the HME process in real time. This review gives a comprehensive overview of the application of machine learning algorithms for HME processes, with a focus on pharmaceutical HME applications. The main current challenges in the application of machine learning algorithms for pharmaceutical processes are discussed, with potential future directions for the industry.

Coupling hot melt extrusion and fused deposition modeling: Critical properties for successful performance

Interest in 3D printing for pharmaceutical applications has increased in recent years. Compared to other 3D printing techniques, hot melt extrusion (HME)-based fused deposition modeling (FDM) 3D printing has been the most extensively investigated for patient-focused dosage. HME technology can be coupled with FDM 3D printing as a continuous manufacturing process. However, the crucial pharmaceutical polymers, formulation and process parameters must be investigated to establish HME-coupled FDM 3D printing. These advancements will lead the way towards developing continuous drug delivery systems for personalized therapy. This brief overview classifies pharmaceutical additive manufacturing, Hot Melt Extrusion, and Fused Deposition Modeling 3D printing techniques with a focus on coupling HME and FDM 3D printing processes. It also provides insights on the critical material properties, process and equipment parameters and limitations of successful HME-coupled FDM systems.

Pharmaceutical Co-Crystals, Salts, and Co-Amorphous Systems: A Novel Opportunity of Hot Melt Extrusion

Enhancing the solubility of active drug ingredients is a major challenge faced by scientists and researchers. Different approaches have been explored for the enhancement of solubility and physicochemical properties of drugs, without affecting their stability or pharmacological activity. Among the various strategies available, pharmaceutical co-crystals, co-amorphous systems, and pharmaceutical salts as multicomponent systems (MCS) have gained interest to improve physicochemical properties of drugs. Development of MCS by conventional methods involves the utilization of excess amount of solvents, thus, making the product prone to instability, and may also cause harmful side effects in patients. Scale up is critical and involves the investment of huge capital and time. Lately, hot-melt extrusion has been utilized in the development of MCS to enhance solubility, bioavailability, stability, and physicochemical properties of the drugs. In this review, the authors discussed the development of different MCS produced via hot-melt extrusion technology. Specifically, approaches for screening of co-formers and co-crystals, selection of excipients for co-amorphous systems, pharmaceutical salts, and significance of MCS and process parameters affecting product quality are discussed.

Hot Melt Extrusion and its Application in 3D Printing of Pharmaceuticals

Hot Melt Extrusion (HME) is a continuous pharmaceutical manufacturing process that has been extensively investigated for solubility improvement and taste masking of active pharmaceutical ingredients. Recently, it is being explored for its application in 3D printing. 3D printing of pharmaceuticals allows flexibility of dosage form design, customization of dosage form for personalized therapy and the possibility of complex designs with the inclusion of multiple actives in a single unit dosage form. Fused Deposition Modeling (FDM) is a 3D printing technique with a variety of applications in pharmaceutical dosage form development. FDM process requires a polymer filament as the starting material that can be obtained by hot melt extrusion. Recent reports suggest enormous applications of a combination of hot melt extrusion and FDM technology in 3D printing of pharmaceuticals and need to be investigated further. This review in detail describes the HME process, along with its application in 3D printing. The review also summarizes the published reports on the application of HME coupled with 3D printing technology in drug delivery.

Cocrystallization: Cutting Edge Tool for Physicochemical Modulation of Active Pharmaceutical Ingredients

Cocrystallization is a widely accepted and clinically relevant technique that has prospered very well over the past decades to potentially modify the physicochemical properties of existing active pharmaceutic ingredients (APIs) without compromising their therapeutic benefits. Over time, it has become an integral part of the pre-formulation stage of drug development because of its ability to yield cocrystals with improved properties in a way that other traditional methods cannot easily achieve. Cocrystals are solid crystalline materials composed of two or more than two molecules which are non-covalently bonded in the same crystal lattice. Due to the continuous efforts of pharmaceutical scientists and crystal engineers, today cocrystals have emerged as a cutting edge tool to modulate poor physicochemical properties of APIs such as solubility, permeability, bioavailability, improving poor mechanical properties and taste masking. The success of cocrystals can be traced back by looking at the number of products that are getting regulatory approval. At present, many cocrystals have obtained regulatory approval and they successfully made into the market place followed by a fair number of cocrystals that are currently in the clinical phases. Considering all these facts about cocrystals, the formulation scientists have been inspired to undertake more relevant research to extract out maximum benefits. Here in this review cocrystallization technique will be discussed in detail with respect to its background, different synthesis approaches, synthesis mechanism, application and improvements in drug delivery systems and its regulatory perspective.

Exploring the Complexity of Processing-Induced Dehydration during Hot Melt Extrusion Using In-Line Raman Spectroscopy

The specific aim in this study was to understand the effect of critical process parameters on the solid form composition of model drug compounds during hot melt extrusion using in-line Raman spectroscopy combined with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) modeling for semi-quantitative kinetic profiling. It was observed that the hydrate and anhydrate solid forms of two model drugs in the melts of nitrofurantoin (NF):polyethylene oxide (PEO) and piroxicam (PRX):PEO could be resolved from a MCR-ALS model without an external calibration dataset. Based on this model, the influence of two critical process parameters (shear and temperature) on the solid form composition could be evaluated in a real-time mode and the kinetics of complex transformation pathways could be explored. Additionally, the dehydration pathways of NF monohydrate and PRX monohydrate in molten PEO could be derived. It can be concluded that dehydration of both hydrates in PEO occurs via competing mechanisms—a solution-mediated transformation pathway and a solid–solid transformation, and that the balance between these mechanisms is determined by the combined effect of both temperature and shear. Another important observation was that the water released from these hydrate compounds has a detectable effect on the rheological characteristics of this mixture.

Recent Advances in Understanding the Micro- and Nanoscale Phenomena of Amorphous Solid Dispersions

Many pharmaceutical drugs in the marketplace and discovery pipeline suffer from poor aqueous solubility, thereby limiting their effectiveness for oral delivery. The use of an amorphous solid dispersion (ASD), a mixture of an active pharmaceutical ingredient and a polymer excipient, greatly enhances the aqueous dissolution performance of a drug without the need for chemical modification. Although this method is versatile and scalable, deficient understanding of the interactions between drugs and polymers inhibits ASD rational design. This current Review details recent progress in understanding the mechanisms that control ASD performance. In the solid-state, the use of high-resolution theoretical, computational, and experimental tools resolved the influence of drug/polymer phase behavior and dynamics on stability during storage. During dissolution in aqueous media, novel characterization methods revealed that ASDs can form complex nanostructures, which maintain and improve supersaturation of the drug. The studies discussed here illustrate that nanoscale phenomena, which have been directly observed and quantified, strongly affect the stability and bioavailability of ASD systems, and provide a promising direction for optimizing drug/polymer formulations.

Inline UV/Vis spectroscopy as PAT tool for hot-melt extrusion

Hot-melt extrusion on co-rotating twin screw extruders is a focused technology for the production of pharmaceuticals in the context of Quality by Design. Since it is a continuous process, the potential for minimizing product quality fluctuation is enhanced. A typical application of hot-melt extrusion is the production of solid dispersions, where an active pharmaceutical ingredient (API) is distributed within a polymer matrix carrier. For this dosage form, the product quality is related amongst others to the drug content. This can be monitored on- or inline as critical quality attribute by a process analytical technology (PAT) in order to meet the specific requirements of Quality by Design. In this study, an inline UV/Vis spectrometer from ColVisTec was implemented in an early development twin screw extruder and the performance tested in accordance to the ICH Q2 guideline. Therefore, two API (carbamazepine and theophylline) and one polymer matrix (copovidone) were considered with the main focus on the quantification of the drug load. The obtained results revealed the suitability of the implemented PAT tool to quantify the drug load in a typical range for pharmaceutical applications. The effort for data evaluation was minimal due to univariate data analysis, and in combination with a measurement frequency of 1 Hz, the system is sufficient for real-time data acquisition.

Faster Release of Lumen-Loaded Drugs than Matrix-Loaded Equivalent in Polylactic Acid/Halloysite Nanotubes

Nanocomposite-based drug delivery systems with intrinsic controlled release properties are of great interest in biomedical applications. We report a novel polylactic acid (PLA)/halloysite nanotube (HNT) nanocomposite-based drug delivery system. PLA/HNT nanocomposites have shown immense potential for use in biomedical applications due to their favorable cyto- and hemo-compatibility. The objective of this study was to evaluate the release of active pharmaceutical ingredients (API) from PLA/HNT composites matrix and the effect of preloading the API into the lumen of the HNT on its release profile. Aspirin was used in this study as a model drug as it is a common nonsteroidal anti-inflammatory and antiplatelet agent widely used for various medical conditions. These two types of drug-loaded PLA/HNT nanocomposites were characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), surface wettability and mechanical testing. Statistical analysis was conducted on numerical data. Drug entrapment and in vitro drug release studies were conducted using UV spectrophotometry. Results indicate that aspirin was successfully loaded into the lumen of HNT, which resulted in the sustained release of aspirin from the nanocomposites. Furthermore, the addition of HNT into the polymer matrix increased the mechanical properties, indicating its suitability as a drug-eluting reinforcing agent.

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

INTRODUCTION

Currently, hot melt extrusion (HME) is a promising technology in the pharmaceutical industry, as evidenced by its application to manufacture various FDA-approved commercial products in the market. HME is extensively researched for enhancing the solubility and bioavailability of poor water-soluble drugs, taste masking, and modifying release in drug delivery systems. Additionally, its other novel opportunities or pharmaceutical applications, and capability for continuous manufacturing are being investigated. This efficient, industrially scalable, solvent-free, continuous process can be easily automated and coupled with other novel platforms for continuous manufacturing of pharmaceutical products.

AREAS COVERED

This review focuses on updates on solubility enhancement of poorly water-soluble drugs and process analytical tools such as UV/visible spectrophotometry; near-infrared spectroscopy; Raman spectroscopy; and rheometry for continuous manufacturing, with a special emphasis on fused deposition modeling 3D printing.

EXPERT OPINION

The strengths, weakness, opportunities, threats (SWOT) and availability of commercial products confirmed wide HME applicability in pharmaceutical research. Increased interest in continuous manufacturing processes makes HME a promising strategy for this application. However, there is a need for extensive research using process analytical tools to establish HME as a dependable continuous manufacturing process.

Raman Spectroscopy for Process Analytical Technologies of Pharmaceutical Secondary Manufacturing

As the process analytical technology (PAT) mindset is progressively introduced and adopted by the pharmaceutical companies, there is an increasing demand for effective and versatile real-time analyzers to address the quality assurance challenges of drug manufacturing. In the last decades, Raman spectroscopy has emerged as one of the most promising tools for non-destructive and fast characterization of the pharmaceutical processes. This review summarizes the achieved results of the real-time application of Raman spectroscopy in the field of the secondary manufacturing of pharmaceutical solid dosage forms, covering the most common secondary process steps of a tablet production line. In addition, the feasibility of Raman spectroscopy for real-time control is critically reviewed, and challenges and possible approaches to moving from real-time monitoring to process analytically controlled technologies (PACT) are discussed.

Scale-Up and In-line Monitoring During Continuous Melt Extrusion of an Amorphous Solid Dispersion

Chemical degradation of drug substances remains a major drawback of extrusion. Larger-scale extrusion equipment has advantages over smaller equipment due to deeper flight elements and added flexibility in terms of screw design, unit operations, and residence time. In a previous study, we extruded a meloxicam-copovidone amorphous solid dispersion (ASD) on a Nano-16 extruder and achieved 96.7% purity. The purpose of this study is to introduce a strategy for scaling the process to an extruder with dissimilar geometry and to investigate the impact on the purity of the ASD. The formulation previously optimized on the Nano-16, 10:90 meloxicam and copovidone, was used for scale-up. Our approach to scale-up to the ZSE-18, utilized specific mechanical energy input and degree of fill from the Nano-16. Vacuum was added to prevent hydrolysis of meloxicam. Downstream feeding and micronization of meloxicam were introduced to reduce the residence time. In-line monitoring of the solubilization of meloxicam was monitored with a UV probe positioned at the die. We were able to achieve the same purity of meloxicam with the Micro-18 as we achieved with Nano-16. When process conditions alone were not sufficient, meglumine was added to further stabilize meloxicam. In addition to the chemical stability advantage that meglumine provided, we also observed solubility enhancement which allowed for an increase in drug loading to 20% while maintaining 100% purity.

Taste masking and rheology improvement of drug complexed with beta-cyclodextrin and hydroxypropyl-β-cyclodextrin by hot-melt extrusion

This study aimed to mask fluconazole (FLU) taste and improve its rheological properties by an efficient process of cyclodextrin complexation. For this, hot-melt extrusion (HME) was used to obtain extrudates composed of FLU, hydroxypropylcellulose, and one of two different cyclodextrins (β-cyclodextrin or hydroxypropyl-β-cyclodextrin) maintaining the drug:cyclodextrin molar ratio at 1:0.3 or 1:0.2, respectively. Samples were characterized by physicochemical tests, palatability using e-tongue and antifungal assays. Drug stability was preserved after HME, according to spectroscopy test (correlation coefficient >0.9) and HPLC-assay (100-107%). Flowability was improved in HME systems with compressibility of <12%. Similarly, floodability exhibited significant enhancement (dispersibility <10%). Whereas extrudates of FLU containing only the polymeric matrix led to a slow drug dissolution efficiency (18.6%) and a partial drug taste masking; extrudates containing cyclodextrin accelerated FLU dissolution (dissolution efficiency approx. 30%) and provided a complete drug taste masking. Moreover, HME process could produce drug complexes with high complexation efficiency and preserve its antifungal activity.

Melt extrusion with poorly soluble drugs - An integrated review

Over the last few decades, hot melt extrusion (HME) has emerged as a successful technology for a broad spectrum of applications in the pharmaceutical industry. As indicated by multiple publications and patents, HME is mainly used for the enhancement of solubility and bioavailability of poorly soluble drugs. This review is focused on the recent reports on the solubility enhancement via HME and provides an update for the manufacturing/scaling up aspects of melt extrusion. In addition, drug characterization methods and dissolution studies are discussed. The application of process analytical technology (PAT) tools and use of HME as a continuous manufacturing process may shorten the drug development process; as a result, the latter is becoming the most widely utilized technique in the pharmaceutical industry. The advantages, disadvantages, and practical applications of various PAT tools such as near and mid-infrared, ultraviolet/visible, fluorescence, and Raman spectroscopies are summarized, and the characteristics of other techniques are briefly discussed. Overall, this review also provides an outline for the currently marketed products and analyzes the strengths, weaknesses, opportunities and threats of HME application in the pharmaceutical industry.

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.

Development of an analytical method for crystalline content determination in amorphous solid dispersions produced by hot-melt extrusion using transmission Raman spectroscopy: A feasibility study

The development of a quantitative method determining the crystalline percentage in an amorphous solid dispersion is of great interest in the pharmaceutical field. Indeed, the crystalline Active Pharmaceutical Ingredient transformation into its amorphous state is increasingly used as it enhances the solubility and bioavailability of Biopharmaceutical Classification System class II drugs. One way to produce amorphous solid dispersions is the Hot-Melt Extrusion (HME) process. This study reported the development and the comparison of the analytical performances of two techniques, based on backscattering and transmission Raman spectroscopy, determining the crystalline remaining content in amorphous solid dispersions produced by HME. Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression were performed on preprocessed data and tended towards the same conclusions: for the backscattering Raman results, the use of the DuoScan™ mode improved the PCA and PLS results, due to a larger analyzed sampling volume. For the transmission Raman results, the determination of low crystalline percentages was possible and the best regression model was obtained using this technique. Indeed, the latter acquired spectra through the whole sample volume, in contrast with the previous surface analyses performed using the backscattering mode. This study consequently highlighted the importance of the analyzed sampling volume.

Solid state characterisation and taste masking efficiency evaluation of polymer based extrudates of isoniazid for paediatric administration

Hot melt extrusion has gained considerable attention as a novel technique for taste masking of bitter APIs. The aim of this study was to investigate whether hot melt extrusion could be used to develop taste masked formulations of isoniazid and also to evaluate and correlate different taste assessment methods Two polymers with different physico-chemical properties, Soluplus and Eudragit E-PO were chosen as carriers for the drug. Eudragit E-PO has already been widely used for taste masking due to its selective release properties, while Soluplus has not been studied in this regard but provides a useful comparator of a polymer that should release the drug reasonably efficiently. Polymeric formulations of isoniazid were produced with drug loadings of 20% and 30% w/w. The solid state characteristics of the formulations were assessed by differential scanning calorimetry and powder X-ray diffraction. The taste of isoniazid was assessed using the rodent Brief Access Taste Aversion (BATA) model, while formulations were assessed using the electronic tongue and dissolution under simulated oral conditions. Investigation into the drug loading effect with these two polymers showed that all Soluplus based extrudates with drug loading up to 30% w/w were fully amorphous while Eudragit E-PO based extrudates contained crystalline drug as demonstrated by both DSC and PXRD, dependent on loading. BATA testing of isoniazid gave an IC₅₀ value, i.e. the dose of drug which inhibits 50% of licks, of 11.1mg/mL. Taste assessment of the formulations using both simulated oral drug release and the electronic tongue demonstrated that Eudragit E-PO based formulations had a better taste masking efficiency than Soluplus. This is due to the fact that significantly less isoniazid is released from the Eudragit E-PO based formulations under oral conditions.

Process analytical techniques for hot-melt extrusion and their application to amorphous solid dispersions

Newly developed active pharmaceutical ingredients (APIs) are often poorly soluble in water. As a result the bioavailability of the API in the human body is reduced. One approach to overcome this restriction is the formulation of amorphous solid dispersions (ASDs), e.g., by hot-melt extrusion (HME). Thus, the poorly soluble crystalline form of the API is transferred into a more soluble amorphous form. To reach this aim in HME, the APIs are embedded in a polymer matrix. The resulting amorphous solid dispersions may contain small amounts of residual crystallinity and have the tendency to recrystallize. For the controlled release of the API in the final drug product the amount of crystallinity has to be known. This review assesses the available analytical methods that have been recently used for the characterization of ASDs and the quantification of crystalline API content. Well-established techniques like near- and mid-infrared spectroscopy (NIR and MIR, respectively), Raman spectroscopy, and emerging ones like UV/VIS, terahertz, and ultrasonic spectroscopy are considered in detail. Furthermore, their advantages and limitations are discussed with regard to general practical applicability as process analytical technology (PAT) tools in industrial manufacturing. The review focuses on spectroscopic methods which have been proven as most suitable for in-line and on-line process analytics. Further aspects are spectroscopic techniques that have been or could be integrated into an extruder.

The effects of polymer carrier, hot melt extrusion process and downstream processing parameters on the moisture sorption properties of amorphous solid dispersions

OBJECTIVE

The aim of this study was to evaluate the effect of polymer carrier, hot melt extrusion and downstream processing parameters on the water uptake properties of amorphous solid dispersions.

METHODS

Three polymers and a model drug were used to prepare amorphous solid dispersions utilizing the hot melt extrusion technology. The sorption-desorption isotherms of solid dispersions and their physical mixtures were measured by the dynamic vapour sorption system, and the effects of polymer hydrophobicity, hygroscopicity, molecular weight and the hot melt extrusion process were investigated. Fourier transform infrared (FTIR) imaging was performed to understand the phase separation driven by the moisture.

KEY FINDINGS

Solid dispersions with polymeric carriers with lower hydrophilicity, hygroscopicity and higher molecular weight could sorb less moisture under the high relative humidity (RH) conditions. The water uptake ability of polymer-drug solid dispersion systems were decreased compared with the physical mixture after hot melt extrusion, which might be due to the decreased surface area and porosity. The FTIR imaging indicated that the homogeneity of the drug molecularly dispersed within the polymer matrix was changed after exposure to high RH.

CONCLUSION

Understanding the effect of formulation and processing on the moisture sorption properties of solid dispersions is essential for the development of drug products with desired physical and chemical stability.

The Future of Pharmaceutical Manufacturing Sciences

The entire pharmaceutical sector is in an urgent need of both innovative technological solutions and fundamental scientific work, enabling the production of highly engineered drug products. Commercial-scale manufacturing of complex drug delivery systems (DDSs) using the existing technologies is challenging. This review covers important elements of manufacturing sciences, beginning with risk management strategies and design of experiments (DoE) techniques. Experimental techniques should, where possible, be supported by computational approaches. With that regard, state-of-art mechanistic process modeling techniques are described in detail. Implementation of materials science tools paves the way to molecular-based processing of future DDSs. A snapshot of some of the existing tools is presented. Additionally, general engineering principles are discussed covering process measurement and process control solutions. Last part of the review addresses future manufacturing solutions, covering continuous processing and, specifically, hot-melt processing and printing-based technologies. Finally, challenges related to implementing these technologies as a part of future health care systems are discussed.

Implementation of transmission NIR as a PAT tool for monitoring drug transformation during HME processing

The aim of the work reported herein was to implement process analytical technology (PAT) tools during hot melt extrusion (HME) in order to obtain a better understanding of the relationship between HME processing parameters and the extruded formulations. For the first time two in-line NIR probes (transmission and reflectance) have been coupled with HME to monitor the extrusion of the water insoluble drug indomethacin (IND) in the presence of Soluplus (SOL) or Kollidon VA64 hydrophilic polymers. In-line extrusion monitoring of sheets, produced via a specially designed die, was conducted at various drug/polymer ratios and processing parameters. Characterisation of the extruded transparent sheets was also undertaken by using DSC, XRPD and Raman mapping. Analysis of the experimental findings revealed the production of molecular solutions where IND is homogeneously blended (ascertained by Raman mapping) in the polymer matrices, as it acts as a plasticizer for both hydrophilic polymers. PCA analysis of the recorded NIR signals showed that the screw speed used in HME affects the recorded spectra but not the homogeneity of the embedded drug in the polymer sheets. The IND/VA64 and IND/SOL extruded sheets displayed rapid dissolution rates with 80% and 30% of the IND being released, respectively within the first 20min.

Vibrational spectroscopy and microspectroscopy analyzing qualitatively and quantitatively pharmaceutical hot melt extrudates

Since the last decade, more and more Active Pharmaceutical Ingredient (API) candidates have poor water solubility inducing low bioavailability. These molecules belong to the Biopharmaceutical Classification System (BCS) classes II and IV. Thanks to Hot-Melt Extrusion (HME), it is possible to incorporate these candidates in pharmaceutical solid forms. Indeed, HME increases the solubility and the bioavailability of these drugs by encompassing them in a polymeric carrier and by forming solid dispersions. Moreover, in 2004, the FDA's guidance initiative promoted the usefulness of Process Analytical Technology (PAT) tools when developing a manufacturing process. Indeed, the main objective when developing a new pharmaceutical process is the product quality throughout the production chain. The trend is to follow this parameter in real-time in order to react immediately when there is a bias. Vibrational spectroscopic techniques, NIR and Raman, are useful to analyze processes in-line. Moreover, off-line Raman microspectroscopy is more and more used when developing new pharmaceutical processes or when analyzing optimized ones by combining the advantages of Raman spectroscopy and imaging. It is an interesting tool for homogeneity and spatial distribution studies. This review treats about spectroscopic techniques analyzing a HME process, as well off-line as in-line, presenting their advantages and their complementarities.

Integrating artificial and human intelligence into tablet production process

We developed a new machine learning-based method in order to facilitate the manufacturing processes of pharmaceutical products, such as tablets, in accordance with the Process Analytical Technology (PAT) and Quality by Design (QbD) initiatives. Our approach combines the data, available from prior production runs, with machine learning algorithms that are assisted by a human operator with expert knowledge of the production process. The process parameters encompass those that relate to the attributes of the precursor raw materials and those that relate to the manufacturing process itself. During manufacturing, our method allows production operator to inspect the impacts of various settings of process parameters within their proven acceptable range with the purpose of choosing the most promising values in advance of the actual batch manufacture. The interaction between the human operator and the artificial intelligence system provides improved performance and quality. We successfully implemented the method on data provided by a pharmaceutical company for a particular product, a tablet, under development. We tested the accuracy of the method in comparison with some other machine learning approaches. The method is especially suitable for analyzing manufacturing processes characterized by a limited amount of data.