Multifunctional coprocessed excipients for improved tabletting performance

Critical review on the role of excipient properties in pharmaceutical powder-to-tablet continuous manufacturing

INTRODUCTION

The pharmaceutical industry is gradually changing batch-wise manufacturing processes to continuous manufacturing processes, due to the advantages it has to offer. The final product quality and process efficiency of continuous manufacturing processes is among others impacted by the properties of the raw materials. Existing knowledge on the role of raw material properties in batch processing is however not directly transferable to continuous processes, due to the inherent differences between batch and continuous processes.

AREAS COVERED

A review is performed to evaluate the role of excipient properties for different unit operations used in continuous manufacturing processes. Unit operations that will be discussed include feeding, blending, granulation, final blending, and compression.

EXPERT OPINION

Although the potency of continuous manufacturing is widely recognized, full utilization still requires a number of challenges to be addressed effectively. An expert opinion will be provided that discusses those challenges and potential solutions to overcome those challenges. The provided overview can serve as a framework for the pharmaceutical industry to push ahead process optimization and formulation development for continuous manufacturing processes.

Cleaning of direct compression continuous manufacturing equipment through displacement of API residues by excipients

This feasibility study evaluates a cleaning process designed to avoid the use of detergents and reduce operator exposure to the active pharmaceutical ingredient (API). The continuous manufacturing equipment was cleaned using excipients to displace ibuprofen residues from the system. The cleaning process was performed using 3.0 kg of Prosolv® and 3.0 kg of Tablettose® 70. The impact of different volumetric feed rates of the cleaning excipient was assessed. The displacement of API and blend residues was evaluated with in-line near infrared (NIR) spectroscopy. Principal component analysis (PCA) was performed to evaluate the cleaning progress as the Prosolv® flowed through the feeder, mixer and stream sampler. In-place Raman spectra were acquired from the material sticking to detect the ibuprofen residues. The study showed that Prosolv® and Tablettose® can remove ibuprofen residues effectively from the hopper, feeder screw, mixer paddles, shaft and stream sampler. The Process Analytical Technology (PAT) system can be utilized to detect API displacement during the cleaning process. However, dismantling and manual cleaning was required to remove material sticking at the surfaces adjacent to the rotating feeder screws and mixer paddles.

Application of co-precipitated glutinous rice starch as a multifunctional excipient in direct compression tablets

Two key properties of excipients for inclusion in direct compression tablets are flowability and compactibility. Glutinous rice starch (GRS) has poor flowability, which limits its use in direct compression tablets. This study aimed to create a multifunctional direct compression excipient (filler binder disintegrant) with improved flowability from GRS by the co-precipitation method. The physicochemical and pharmaceutical properties of the co-precipitated GRS (cpGRS) were investigated. The optimum conditions for producing cpGRS (0.43 M sodium hydroxide solution, 7.09% PVP K30, 14.02% calcium carbonate, 95 min of mixing time and pH of 6.97) resulted in 68.80% yield, fair to good flowability, acceptable tablet strength, and fast disintegration. The FT-IR spectra of cpGRS showed no significant shifts in the key peaks, which indicates that there was an absence of chemical interactions within cpGRS. X-ray diffractograms also showed no significant changes, indicating that the GRS granules, calcium carbonate, and PVP K30 components remained unaltered during co-precipitation. cpGRS also demonstrated a dilution capacity of 50% when paracetamol was used as model drug. When cpGRS was combined with domperidone or propranolol hydrochloride it showed a better deformation capability than the physical mixtures. Although cpGRS was sensitive to lubricant, the hardness and tensile strength were higher than common strength for general purpose use in tablets. When compared to the physical mixture, pregelatinized starch and directly compressible calcium carbonate, the results showed that cpGRS tablets of both model drugs passed the friability test, demonstrated the best disintegration property, provided the fastest and highest drug release profile for propranolol, and improved the drug release profile for domperidone. For propranolol-cpGRS tablets, dissolution medium at different pH did not affect the dissolution profile. For domperidone-cpGRS tablets, the pH of dissolution medium did affect the dissolution profile of the tablets. This was according to the API solubility. These results reveal that cpGRS is an excellent multifunctional i.e., filler, binder, and disintegrant excipient suitable for direct compression tablets. The main component is natural. The preparation method is simple, quick, and efficient. This method does not produce harmful waste and requires only basic equipment, and affordable reactants and devices.

Effect of process parameters in high shear granulation on characteristics of a novel co-processed mesoporous silica material

In this study, insights into the development and optimization of a co-processed excipient based on mesoporous silica are presented. The main advantage of such a material is that it is appropriate for direct tablet compression and has a sufficiently large specific surface area to be suitable for potential subsequent drug loading and formulation of (amorphous) solid dispersions. Our aim was to use a Design of Experiments approach to investigate which process parameters in high shear granulation affect the characteristics of such a co-processed material. The parameters included were the amount of binder (isomalt), the amount of water (granulation liquid), the water addition rate and the speed of the impeller. The responses evaluated and modelled were particle size and its distribution, specific surface area, bulk density, flowability, compressibility and compactibility. The models obtained showed good quality in terms of goodness of fit and predictive power. Active effects were identified for all responses, giving a thorough insight into factors affecting the material characteristics. Optimization experiments resulted in products with the desired characteristics (high specific surface area, large particle size, good flow and compression properties) and confirmed the validity of the generated models.

Lactose in tablets: Functionality, critical material attributes, applications, modifications and co-processed excipients

Lactose is one of the most widespread excipients used in the pharmaceutical industry. Because of its water solubility and acceptable flowability, lactose is generally added into tablet formulation to improve wettability and undesirable flowability. Based on Quality by Design, a better understanding of the critical material attributes (CMAs) of raw materials is beneficial in guiding the improvement of tablet quality and the development of lactose. Additionally, the modifications and co-processing of lactose can introduce more-desirable characteristics to the resulting particles. This review focuses on the functionality, CMAs, applications, modifications and co-processing of lactose in tablets.

Development and Characterization of Pentaerythritol-EudragitRS100 Co-processed Excipients as Solid Dispersion Carriers for Enhanced Aqueous Solubility, In Vitro Dissolution, and Ex Vivo Permeation of Atorvastatin

Atorvastatin (ATV), a lipid-lowering agent, has low oral bioavailability due to its poor water solubility, permeability, and low dissolution rate. Therefore, pentaerythritol-EudragitRS100 co-processed excipients (PECE) were synthesized, and their feasibility as solid dispersion carriers (ATV-PECE-SD) for improving the solubility, permeability, and dissolution rate of ATV was explored. Solid dispersions were assessed in terms of particle size and zeta potential, and solubility, in vitro dissolution, and ex vivo permeation studies were studied. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) were used as characterization tools. ATV-PECE-SD3 (1:4) formulations exhibited a small particle size with high stability. Physicochemical evaluation evidenced the formation of solid dispersion due to the involvement of weak electrostatic interaction between the polar functional groups of ATV and PECE carriers. ATV-PECE-SD3 (1:4) significantly enhanced the water solubility by ∼43-fold compared to pure ATV. In vitro dissolution studies showed that optimized formulation enhanced the dissolution rate of ATV compared to pure ATV. Ex vivo permeation results revealed that ATV-PECE-SD3 (1:4) enhanced the permeation rate of ATV compared to pure ATV. The optimized formulations significantly improved the dissolution rate of ATV in the fed state due to the food effect and micelle formation mechanism compared to the fasted state. The study concludes that co-processed excipients could be used as promising solid dispersion carriers to enhance the aqueous solubility, permeability, and dissolution rate of ATV.

Updates on applications of low-viscosity grade Hydroxypropyl methylcellulose in coprocessing for improvement of physical properties of pharmaceutical powders

Hydroxypropyl methylcellulose (HPMC) is an important polymeric excipient. Its versatility in terms of molecular weights and viscosity grades is the basis for its wide and successful application in the pharmaceutical industry. Low viscosity grades of HPMC (like E3 and E5) have been used as physical modifiers for pharmaceutical powders in recent years due to their unique physicochemical and biological properties (e.g., low surface tension, high T_g, strong hydrogen bonding ability, etc.). Such modification is the co-processing of HPMC with a drug/excipient to create composite particles (CPs) for the purpose of providing synergistic effects of functional improvement as well as of masking undesirable properties of the powder (e.g., flowability, compressibility, compactibility, solubility, stability, etc.). Therefore, given its irreplaceability and tremendous opportunities for future developments, this review summarized and updated studies on improving the functional properties of drugs and/or excipients by forming CPs with low-viscosity HPMC, analyzed and exploited the improvement mechanisms (e.g., improved surface properties, increased polarity, hydrogen bonding, etc.) for the further development of novel co-processed pharmaceutical powders containing HPMC. It also provides an outlook on the future applications of HPMC, aiming to provide a reference on the crucial role of HPMC in various areas for interested readers.

Alginate-based matrix tablets for drug delivery

INTRODUCTION

As a nature-derived polymer with swelling and gelling properties, alginate has found wide biopharma-relevant applications. However, there is comparatively limited attention on alginate in tablet formulations. Therefore, this review aimed to provide an overview of the applications of alginate in solid dosage form formulations.

AREAS COVERED

This review outlines the role of alginate for oral sustained release formulations. For better insights into its application in drug delivery, the mechanisms of drug release from alginate matrices are discussed alongside the alginate inherent properties and drug properties. Specifically, the influence of alginate properties and formulation components on the resultant alginate gel and subsequent drug release is reviewed. Modifications of the alginate to improve its properties in modulating drug release are also discussed.

EXPERT OPINION

Alginate-based matrix tablets is useful for sustaining drug release. As a nature-derived polymer, batch consistency and stability raise some concerns about employing alginate in formulations. Furthermore, the alginate gel properties can be affected by formulation components, pH of the dissolution environment and the tablet matrix micro-environment pH. Conscientious efforts are pivotal to addressing these formulation challenges to increase the utilization of alginate in oral solid dosage forms.

Co-processed tablet excipient composition, its preparation and use: US10071059 B2: patent spotlight

Co-processing involves the incorporation of one excipients into the particle structure of other excipients to overcome the deficiencies of each excipients. The current patent describes the co-processing of microcrystalline cellulose and mannitol via fluid bed agglomeration with an aim to limit the use of lubricant in tablet composition. The co-processed excipients blend was compared with the physical blend of excipients and characterized for scanning electron microscopy, disintegration and hardness. The average particle size of co-processed excipients was less than 0.55 mm, characterized by large individual lactose coated particles whereas, the physical blend particles are uncoated and irregular in shape. Tablets made from both physical blend and co-processed excipients were compared. As per the hardness and disintegration studies, with increase in mixing time of excipients both hardness and disintegration time decreases.

Hydrochlorothiazide/Losartan Potassium Tablet Prepared by Direct Compression

Hydrochlorothiazide (HCTZ)/losartan potassium (LOS-K) was used as a model drug to prepare compound tablets through the investigation of the compression and mechanical properties of mixed powders to determine the formulation and preparation factors, followed by D-optimal mixture experimental design to optimize the final parameters. The type and amount of lactose monohydrate (SuperTab®14SD, 19.53−26.91%), microcrystalline cellulose (MCC PH102, 32.86−43.31%), pre-gelatinized starch (Starch-1500, 10.96−15.91%), and magnesium stearate (0.7%) were determined according to the compressive work, stress relaxation curves, and Py value. Then, the compression mechanism of the mixed powder was investigated by the Kawakita equation, Shapiro equation, and Heckel analysis, and the mixed powder was classified as a Class-II powder. The compaction pressure (150−300 MPa) and tableting speed (1200−2400 Tab/h) were recommended. A D-optimal mixture experimental design was utilized to select the optimal formulation (No 1, 26.027% lactose monohydrate, 32.811% MCC PH102, and 15.462% pregelatinized starch) according to the drug dissolution rate, using Hyzaar® tablets as a control. Following oral administration in beagle dogs, there were no significant differences in bioavailability between the No. 1 tablet and the Hyzaar® tablet in HCTZ, losartan carboxylic acid (E-3174), and LOS-K (F < F0.05). Thus, formulation and preparation factors were determined according to the combination of the compression and mechanical properties of the mixed powder and quality of tablets, which was demonstrated to be a feasible method in direct powder compression.

Exploiting synergistic effects of brittle and plastic excipients in directly compressible formulations of Sitagliptin phosphate and Sitagliptin hydrochloride

Direct compression (DC) is the simplest and most economical way to produce pharmaceutical tablets. Ideally, it consists of only two steps: dry blending of a drug substance(s) with excipients followed by compressing the powder mixture into tablets. In this study, immediate-release film-coated tablets containing either Sitagliptin phosphate or Sitagliptin hydrochloride were developed using DC technique.After establishing the optimum ratio of ductile and brittle excipients, five formulations were compressed into tablets using a rotary press and finally film coated. Both powders and tablets were examined by standard pharmacopoeial methods. It has been shown that the simultaneous use of excipients with different physical properties, i.e., ductile microcrystalline cellulose and brittle anhydrous dibasic calcium phosphate, produces a synergistic effect, allowing preparation of Sitagliptin DC tablets with good mechanical strength (tensile strength over 2 N/mm²), rapid disintegration (shorter than 2 min), and fast release of the drug substance (85% of the drug is dissolved within 15 minutes). It was found that the type of calcium phosphate excipient used had a large effect on the properties of the sitagliptin tablets. All formulations developed showed good chemical stability, even when stored under stress conditions (50 °C/80% RH).

Improving Tableting Performance of Lactose Monohydrate by Fluid-Bed Melt Granulation Co-Processing

Co-processing is commonly used approach to improve functional characteristics of pharmaceutical excipients to become suitable for tablet production by direct compression. This study aimed to improve tableting characteristics of lactose monohydrate (LMH) by co-processing by fluid-bed melt granulation with addition of hydrophilic (PEG 4000 and poloxamer 188) and lipophilic (glyceryl palmitostearate) meltable binders. In addition to binding purpose, hydrophilic and lipophilic excipients were added to achieve self-lubricating properties of mixture. Co-processed mixtures exhibit superior flow properties compared to pure LMH and comparable or better flowability relative to commercial excipient Ludipress^®. Compaction of mixtures co-processed with 20% PEG 4000 and 20% poloxamer 188 resulted in tablets with acceptable tensile strength (>2 MPa) and good lubricating properties (ejection and detachment stress values below 5 MPa) in a wide range of compression pressures. While the best lubricating properties were observed when glyceryl palmitostearate was used as meltable binder, obtained tablets failed to fulfil required mechanical characteristics. Although addition of meltable binder improves interparticle bonding, disintegration time was not prolonged compared to commercial excipient Ludipress^®. Co-processed mixtures containing 20% of either PEG 4000 or poloxamer 188 showed superior tabletability and lubricant properties relative to LMH and Ludipress^® and can be good candidates for tablet production by direct compression.

A review of emerging technologies enabling improved solid oral dosage form manufacturing and processing

Tablets are the most widely utilized solid oral dosage forms because of the advantages of self-administration, stability, ease of handling, transportation, and good patient compliance. Over time, extensive advances have been made in tableting technology. This review aims to provide an insight about the advances in tablet excipients, manufacturing, analytical techniques and deployment of Quality by Design (QbD). Various excipients offering novel functionalities such as solubility enhancement, super-disintegration, taste masking and drug release modifications have been developed. Furthermore, co-processed multifunctional ready-to-use excipients, particularly for tablet dosage forms, have benefitted manufacturing with shorter processing times. Advances in granulation methods, including moist, thermal adhesion, steam, melt, freeze, foam, reverse wet and pneumatic dry granulation, have been proposed to improve product and process performance. Furthermore, methods for particle engineering including hot melt extrusion, extrusion-spheronization, injection molding, spray drying / congealing, co-precipitation and nanotechnology-based approaches have been employed to produce robust tablet formulations. A wide range of tableting technologies including rapidly disintegrating, matrix, tablet-in-tablet, tablet-in-capsule, multilayer tablets and multiparticulate systems have been developed to achieve customized formulation performance. In addition to conventional invasive characterization methods, novel techniques based on laser, tomography, fluorescence, spectroscopy and acoustic approaches have been developed to assess the physical-mechanical attributes of tablet formulations in a non- or minimally invasive manner. Conventional UV-Visible spectroscopy method has been improved (e.g. fiber-optic probes and UV imaging-based approaches) to efficiently record the dissolution profile of tablet formulations. Numerous modifications in tableting presses have also been made to aid machine product changeover, cleaning, and enhance efficiency and productivity. Various process analytical technologies have been employed to track the formulation properties and critical process parameters. These advances will contribute to a strategy for robust tablet dosage forms with excellent performance attributes.

Formulation Study of a Co-Processed, Rice Starch-Based, All-in-One Excipient for Direct Compression Using the SeDeM-ODT Expert System

A co-processed, rice starch-based excipient (CS), previously developed and shown to exhibit good pharmaceutical properties, is investigated as an all-in-one excipient for direct compression (DC). An SeDeM-ODT expert system is applied to evaluate the formulation containing CS, in comparison with those containing the physical mixture and the commercial DC excipients. The results revealed that CS showed acceptable values in all six incidence factors of the SeDeM-ODT diagram. In addition, the comprehensive indices (IGC and IGCB) were higher than 5.0, which indicated that CS could be compressed with DC technique without additional blending with a disintegrant in tablet formulation. The formulation study suggested that CS can be diluted up to 60% in the formulation to compensate for unsatisfactory properties of paracetamol. At this percentage, CS-containing tablets exhibited narrow weight variation (1.5%), low friability (0.43%), acceptable drug content (98%), and rapid disintegration (10 s). The dissolution profile of CS displayed that more than 80% of the drug content was released within 2 min. The functionality of CS was comparable to that of high functionality excipient composite (HFEC), whereas other excipients were unsuccessful in formulating the tablets. These results indicated that CS was a suitable all-in-one excipient for application in DC of tablets.

Comparison of Flow and Compression Properties of Four Lactose-Based Co-Processed Excipients: Cellactose® 80, CombiLac®, MicroceLac® 100, and StarLac®

The utilization of co-processed excipients (CPEs) represents a novel approach to the preparation of orally disintegrating tablets by direct compression. Flow, consolidation, and compression properties of four lactose-based CPEs-Cellactose® 80, CombiLac®, MicroceLac® 100, and StarLac®-were investigated using different methods, including granulometry, powder rheometry, and tablet compaction under three pressures. Due to the similar composition and the same preparation technique (spray drying), the properties of CPEs and their compacts were generally comparable. The most pronounced differences were observed in flowability, undissolved fraction after 3 min and 24 h, energy of plastic deformation (E2), ejection force, consolidation behavior, and compact friability. Cellactose® 80 exhibited the most pronounced consolidation behavior, the lowest values of ejection force, and high friability of compacts. CombiLac® showed excellent flow properties but insufficient friability, except for compacts prepared at the highest compression pressure (182 MPa). MicroceLac® 100 displayed the poorest flow properties, lower ejection forces, and the best mechanical resistance of compacts. StarLac® showed excellent flow properties, the lowest amounts of undissolved fraction, the highest ejection force values, and the worst compact mechanical resistance. The obtained results revealed that higher compression pressures need to be used or further excipients have to be added to all tested materials in order to improve the friability and tensile strength of formed tablets, except for MicroceLac® 100.

Levothyroxine sodium pentahydrate tablets - formulation considerations

Even though levothyroxine sodium pentahydrate tablets have been in the market since 1955, there continue to be recalls due to sub potency. We have comprehensively reviewed the factors affecting its stability in solid oral dosage forms. A compilation of marketed formulation compositions enabled the identification of the potential 'problem excipients'. Two excipient properties, hygroscopicity and microenvironmental acidity, appeared to be responsible for inducing drug instability. In drug products, depending on the formulation composition and storage conditions, the pentahydrate can dehydrate to highly reactive levothyroxine sodium monohydrate, or undergo salt disproportionation to the free acid form of the drug. The USP assay method (HPLC based) is insensitive to these different physical forms of the drug. The influence of physical form of levothyroxine on its chemical stability is incompletely understood. The USP has five product-specific dissolution tests reflecting the complexity in its evaluation.

Monitoring of high-load dose formulations based on co-processed and non co-processed excipients

This work presents the evaluation of a co-processed material for high-load dose formulations and its real-time monitoring by near-infrared (NIR) spectroscopy at the tablet press feed frame. The powder and tableting properties of co-processed material blends were evaluated and compared to the blend of the individual excipients. The formulations with the co-processed material showed excellent flow properties and were superior to the physical blend of individual excipients. Two NIR spectroscopic methods were developed to monitor ibuprofen concentration between 40.0 and 60.0% w/w, one method using a co-processed material as the main excipient and the other using the blend of the individual excipients. The NIR spectra were obtained while the powder blends flowed within a three-chamber feed frame from a Fette 3090 tablet press. The NIR spectroscopic method with the co-processed material presented better performance with significantly lower prediction error. Variographic analysis demonstrated that using the co-processed material considerably reduces the sampling and analytical errors in the in-line determination of ibuprofen. The authors understand that this is the first study where the sampling errors are evaluated as a function of the excipients used in the pharmaceutical formulation. This study demonstrated that selecting a suitable excipient for the formulation helps optimize the manufacturing process, reducing the magnitude of the total measurement error.

Application of SeDeM Expert System in the development of novel directly compressible co-processed excipients via co-processing

Background

Computer-aided formulation design is gaining fantastic attention in chemical engineering of high functionality pharmaceutical materials for dosage form manufacture. To accelerate development of novel formulations in a quality-by-design perspective, SeDeM Expert System preformulation algorithm was developed as a tool for the design of solid drug delivery systems and for prediction of direct compression manufacturability of solid formulations. This research aims to integrate SeDeM Expert System into particle engineering design space of co-processing of solid excipients to develop novel composites with optimum direct compression propensity, using corn starch and microcrystalline cellulose powders as model primary excipients.

Result

The data and information generated from the expert system have elucidated the bulk-level characteristics of the primary excipients, enabled computation of the optimum co-processing ratio of the ingredients, and validated the impact of co-processing on material functionality. The experimental flowability (7.78±0.17), compressibility functions (5.16±0.14), parameter profile (0.92), and parametric profile index (6.72±0.27) of the engineered composites, were within the acceptable thresholds. With a reliability constant of 0.961, the net direct compression propensity of the composites expressed as Good Compression Index (6.46±0.26) was superior to that of the primary excipients, but comparable to reference co-processed materials, StarLac® (6.44±0.14) and MicroceLac®100 (6.58±0.03).

Conclusion

Application of SeDeM Expert System in particle engineering via co-processing has provided an accelerated upstream proactive mechanism for designing directly compressible co-processed excipients in a quality-by-design fashion. A four-stage systematic methodology of co-processing of solid excipients was postulated. Stage I entails the characterization of CMAs of both defective and corrective excipients, and elucidation of their physicomechanical limitations using SeDeM diagrams. Stage II involves computation of loading capacity of the corrective excipient using dilution potential equation. Stage III entails the selection of co-processing technique based on desired Critical Material Attributes as revealed by the information obtained from Stage I. Stage IV evaluates the impact of co-processing by monitoring the critical behavior of the engineered composites with a decision on either to accept or reject the product.

Preparation and Characterization of Co-Processed Mannitol and Sorbitol Using NanoCrySP Technology

Particle engineering of excipients, at sub-particulate level using co-processing, can provide high functionality excipients. NanoCrySP technology has been recently explored as a novel approach for the generation of nanocrystalline solid dispersion of poorly soluble drugs, using spray drying process. The purpose of the present study was to generate co-processed mannitol and sorbitol (SD-CSM) using NanoCrySP technology having similar composition to commercial co-processed excipient (Compressol® SM, CP). The characterization of excipients was performed to evaluate their various physicomechanical properties. The sub-micron crystallite size of sorbitol in the matrix of mannitol was determined using the Williamson-Hall equation and Halder-Wagner equation. The reduction in crystallite size of sorbitol and mannitol, lower melting point, and lower heat of fusion of SD-CSM could be responsible for excellent compactibility, better tabletability, and comparable compressibility with respect to CP. This was confirmed by the compressibility-tabletability-compactibility (CTC) profile and Heckel plot analysis. Overall, SD-CSM generated using NanoCrySP technology improved functionalities of excipients over CP and would be useful for direct compression application.

Critical Tools in Tableting Research: Using Compaction Simulator and Quality by Design (QbD) to Evaluate Lubricants' Effect in Direct Compressible Formulation

As commonly known, the product development stage is quite complex, requires intensive knowledge, and is time-consuming. The selection of the excipients with the proper functionality and their corresponding levels is critical to drug product performance. The objective of this study was to apply quality by design (QbD) principles for formulation development and to define the desired product quality profile (QTPP) and critical quality attributes (CQA) of a product. QbD is a risk- and science-based holistic approach for upgraded pharmaceutical development. In this study, Ibuprofen DC 85W was used as a model drug, Cellactose® 80 along with MicroceLac® 100 as a filler, and magnesium stearate, stearic acid, and sodium stearyl fumarate as lubricants. By applying different formulation parameters to the filler and lubricants, the QbD approach furthers the understanding of the effect of critical formulation and process parameters on CQAs and the contribution to the overall quality of the drug product. An experimental design study was conducted to determine the changes of the obtained outputs of the formulations, which were evaluated using the Modde Pro 12.1 statistical computer program that enables optimization by modeling complex relationships. The results of the optimum formulation revealed that MicroceLac® 100 was the superior filler, while magnesium stearate at 1% was the optimum lubricant. A design space that indicates the safety operation limits for the process and formulation variables was also created. This study enriches the understanding of the effect of excipients in formulation and assists in enhancing formulation design using experimental design and mathematical modeling methods in the frame of the QbD approach.

Loss-in-weight feeding, powder flow and electrostatic evaluation for direct compression hydroxypropyl methylcellulose (HPMC) to support continuous manufacturing

Minimizing variability in the feeding process is important for continuous manufacturing since materials are fed individually and can impact the final product. This study demonstrates the importance of measuring powder properties and highlights the need to characterize the feeding performance both offline with multiple refills and in the intended configuration for the continuous manufacturing equipment. The standard grade hydroxypropyl methylcellulose (HPMC) had material buildup on the loss-in-weight feeder barrel from triboelectric charging and resulted in more mass flow excursions and failed refills which were not observed with the direct compression grades. The location of the electrostatic buildup changed when the feeder was connected to a hopper instead of feeding offline into a collection bucket. Overall, the direct compression HPMC exhibited better flow which resulted in more accurate loss-in-weight feeding with less excursions from the target mass flow and all refills were completed in the first attempt. The improvements with the direct compression HPMC would be beneficial when running any continuous process (wet granulation, roller compaction, or direct compression) or other processes where loss-in-weight feeding is utilized, such as melt extrusion or twin screw granulation.

Co-processing of small molecule excipients with polymers to improve functionality

INTRODUCTION

Polymers have various applications such as binder, film coating agent, stabilizer, drug release modification, and as primary packaging materials. Recently, they have been explored in co-processing technique to improve the functionality of small molecule excipients (SMEs). Co-processing is a concept wherein two or more excipients interact at sub-particle level to provide synergy in functionality and minimize drawbacks of individual excipients.

AREA COVERED

The present review highlights the application of co-processing to improve the functionality of SMEs using polymers; physicochemical and mechanical properties of polymers for co-processing; advantages of co-processed excipients for different applications; functionality enhancement of co-processed excipients; novel concepts/methods for co-processing; mechanistic insights on co-processing and commercial products available in the market.

EXPERT OPINION

Most of the SMEs do not possess optimal multifunctional properties like flow, compressibility, compactibility, and disintegration ability, required to compensate for poorly compactable drugs. Some of these drawbacks can be overcome by co-processing of SMEs with polymers. For example, co-processing of a brittle SME and plastic material (polymer) can provide a synergistic effect and result in the generation of single entity multi-functional excipient. Besides, novel co-processed excipients generated using combinations of SMEs and polymers can also generate intellectual property rights.

Spray Drying for Direct Compression of Pharmaceuticals

Tableting by direct compression (DC) is one of the simplest and most cost-effective drug manufacturing approaches. However, most active pharmaceutical ingredients (APIs) and excipients lack the compression and flow properties required to meet the needs of high-speed industrial tablet presses. Therefore, the majority of DC APIs and excipients are modified via processing/co-processing particle engineering techniques to boost their properties. Spray drying is one of the most commonly employed techniques to prepare DC grades of APIs and excipients with prominent advantages. This review aims to present an overview of the commercially marketed and investigationally-prepared DC APIs and excipients produced by spray drying.

Applications of polymer blends in drug delivery

Background

Polymers are essential components of many drug delivery systems and biomedical products. Despite the utility of many currently available polymers, there exists a demand for materials with improved characteristics and functionality. Due to the extensive safety testing required for new excipient approval, the introduction and use of new polymers is considerably limited. The blending of currently approved polymers provides a valuable solution by which the limitations of individual polymers can be addressed.

Main body

Polymer blends combine two or more polymers resulting in improved, augmented, or customized properties and functionality which can result in significant advantages in drug delivery applications. This review discusses the rationale for the use of polymer blends and blend polymer-polymer interactions. It provides examples of their use in commercially marketed products and drug delivery systems. Examples of polymer blends in amorphous solid dispersions and biodegradable systems are also discussed. A classification scheme for polymer blends based on the level of material processing and interaction is presented.

Conclusion

The use of polymer blends represents a valuable and under-utilized resource in addressing a diverse range of drug delivery challenges. It is anticipated that new drug molecule development challenges such as bioavailability enhancement and the demand for enabling excipients will lead to increased applications of polymer blends in pharmaceutical products.

Graphical abstract

Preparation and optimization of multi-functional directly compressible excipient: an integrated approach of principal component analysis and design of experiments

Developing a new excipient and obtaining its market approval is an expensive, time-consuming, and complex process. The application of a multivariate analytical approach - principal component analysis (PCA) - in combination with the design of experiments (DoE) approach can make the process of developing co-processed excipient cost-effective and rapid. The present investigation was aimed to demonstrate the applicability of the DoE approach and PCA in developing a co-processed excipient by using the spray drying technique. The preliminary studies suggested a significant effect of inlet air temperature (X ₁) and polymer ratio [chitosan chlorhydrate (CC): mannitol - X ₂) on critical product characteristics so they were selected as independent variables in 3² full factorial design. The result of regression analysis suggested a significant effect of both independent variables on all response variables. The PCA of practically obtained value suggested a strong effect of all the selected response variables on the model. The prepared co-processed excipient had better tableting properties compared to the physical mixture of excipients and was able to accommodate more than 80% drug without compromising the flow property and compressibility. The present investigation successfully proved the applicability PCA and DoE approach as an effective and rapid tool for optimizing process parameters and formulation composition for preparing a directly compressible co-processed excipient.

A Spray-Dried, Co-Processed Rice Starch as a Multifunctional Excipient for Direct Compression

A new co-processed, rice starch-based excipient (CS) was developed via a spray-drying technique. Native rice starch (RS) was suspended in aqueous solutions of 10%–15% cross-linked carboxymethyl rice starch (CCMS) and 0.5%–6.75% silicon dioxide (in the form of sodium silicate), before spray drying. The resulting CSs were obtained as spherical agglomerates, with improved flowability. The compressibility study revealed an improved plastic deformation profile of RS, leading to better compaction and tensile strength. The presence of CCMS also ensured a rapid disintegration of the compressed tablets. CS-CCMS:SiO₂ (10:2.7), prepared with 10% CCMS, 2.7% silicon dioxide, and 40% solid content, was found to exhibit the best characteristics. Compared to the two commercial DC excipients, Prosolv^® and Tablettose^®, the flow property of CS-CCMS:SiO₂ (10:2.7) was not significantly different, while the tensile strength was 23%: lower than that of Prosolv^® but 4 times higher than that of Tablettose^® at 196 MPa compression force. The disintegration time of CS-CCMS:SiO₂ (10:2.7) tablet (28 s) was practically identical to that of Tablettose^® tablet (26 s) and far superior to that of Prosolv^® tablet (>30 min). These results show that CSs could potentially be employed as a multifunctional excipient for the manufacturing of commercial tablets by DC.

Application of 3² Full Factorial Design and Desirability Function for Optimizing The Manufacturing Process for Directly Compressible Multi-Functional Co-Processed Excipient

BACKGROUND

Developing a new excipient and obtaining its market approval is an expensive, time-consuming and complex process. Compared to that, the co-processing of already approved excipients has emerged as a more attractive option for bringing better characteristic excipients to the market. The application of the Design of Experiments (DoE) approach for developing co-processed excipient can make the entire process cost-effective and rapid.

OBJECTIVE

The aim of the present investigation was to demonstrate the applicability of the DoE approach, especially 32 full factorial design, to develop a multi-functional co-processed excipient for the direct compression of model drug - cefixime trihydrate using spray drying technique.

METHODS

The preliminary studies proved the significant effect of atomization pressure (X1) and polymer ratio (microcrystalline cellulose: mannitol - X2) on critical product characteristics, so they were selected as independent variables. The angle of repose, Carr's index, Hausner's ratio, tensile strength and Kuno's constant were selected as response variables.

RESULT

The statistical analysis proved a significant effect of both independent variables on all response variables with a significant p-value < 0.05. The desirability function available in Design Expert 11® software was used to prepare and select the optimized batch. The prepared co-processed excipient had better compressibility than individual excipients and their physical mixture and was able to accommodate more than 40 percent drug without compromising the flow property and compressibility.

CONCLUSION

The present investigation successfully proved the applicability of 32 full factorial design as an effective tool for optimizing the spray drying process to prepare a multi-functional co-processed excipient.

Development of alginate esters as novel multifunctional excipients for direct compression

Methyl ester derivatives of alginic acid have been evaluated as potential multifunctional excipients for pharmaceutical direct compression. The use of alginic acid as an excipient in tablet formulation is limited because of certain drawbacks such as low tablet hardness and poor compressibility. The objective of this work is to improve these properties through esterification of alginic acid, chemical modification commonly used for enhancing the functionality of tableting excipients. It has been observed that the degree of methylation (DM) has a profitable impact in the physico-chemical and mechanical properties of the obtained materials. In general, an increase in the degree of methylation yielded tablets with higher tensile strength and better compressibility. Furthermore, modified alginates exhibited extended disintegration times compared to native alginic acid due to the introduced hydrophobicity. Finally, the functional versatility of the modified alginates as disintegrating and filling/binding agents was tested by formulating them with microcrystalline cellulose and lactose.

Orodispersible Carbamazepine/Hydroxypropyl-β-Cyclodextrin Tablets Obtained by Direct Compression with Five-in-One Co-processed Excipients

The development of orodispersible tablets (ODTs) for poorly soluble and poorly flowable drugs via direct compression is still a challenge. This work aimed to develop ODTs of poorly soluble drugs by combining cyclodextrins that form inclusion complexes to improve wetting and release properties, and directly compressible co-processed excipients able to promote rapid disintegration and solve the poor flowability typical of inclusion complexes. Carbamazepine (CBZ) and hydroxypropyl-β-cyclodextrin (HPβCD) were used, respectively, as a model of a poorly soluble drug with poor flowability and as a solubilizing agent. Specifically, CBZ-an antiepileptic and anticonvulsant drug-may benefit from the studied formulation approach, since some patients have swallowing difficulties or fear of choking and are non-cooperative. Prosolv® ODT G2 and F-Melt® type C were the studied five-in-one co-processed excipients. The complex was prepared by kneading. Flow properties of all materials and main properties of the tablets were characterized. The obtained results showed that ODTs containing CBZ/HPβCD complex can be prepared by direct compression through the addition of co-processed excipients. The simultaneous use of co-processing and cyclodextrin technologies rendered ODTs with an in vitro disintegration time in accordance with the European Pharmacopoeia requirement and with a fast and complete drug dissolution. In conclusion, the combination of five-in-one co-processed excipients and hydrophilic cyclodextrins may help addressing the ODT formulation of poorly soluble drugs with poor flowability, by direct compression and with desired release properties.

New orodispersible mini-tablets for paediatric use - A comparison of isomalt with a mannitol based co-processed excipient

The development of orodispersible mini-tablets (ODMTs) for paediatric use has gained importance within recent years as European authorities set up regulations for developing suitable and palatable dosage forms for paediatric patients. Polyols like mannitol and isomalt are frequently used in the manufacture of tablets where sensory properties have to be taken into account. In literature, ODTMs based on a commercialized co-processed excipient based on mannitol (Ludiflash®) have been already described. Isomalt is known for its pleasant sensory properties and therefore appears to be a good candidate for ODMTs. The feasibility of the direct compression grade of isomalt for the manufacture of ODMTs was assessed and compared to Ludiflash®. Hydrochlorothiazide and enalapril maleate were chosen as model drugs and compressed to 2 mm mini-tablets. ODMTs could be obtained fulfilling the criteria of Ph.Eur. with disintegration times of 180 s or even the FDA limit of 30 s. Dissolution studies and mass variation were fulfilled for all mini-tablets. Acceptance values (AV) ≤ 15 were achieved for formulations based on both isomalt and Ludiflash®. Stability data showed the change of disintegration time and tensile strength as a function of storing time, condition and excipient. Both excipients showed their potential for ODMTs for paediatric use.

Lignin and Cellulose Blends as Pharmaceutical Excipient for Tablet Manufacturing via Direct Compression

Extensive efforts are being made to find alternative uses for lignin (LIG). In the present work the use of this biopolymer as excipient to prepare tablets was studied. For this purpose, LIG was combined with microcrystalline cellulose (MCC) and used as excipients to prepare directly compressed tablets containing a model drug, tetracycline (TC). The excipients contained different concentrations of LIG: 100%, 75%, 50%, 25% and 0% (w/w). Two different compression forces were used (two and five tonnes). When formulations were prepared using LIG as the only excipient, tablets were formed, but they showed lower densities and crushing strength than the ones obtained with only MCC or LIG/MCC blends. Moreover, tablets prepared using five tonnes of compression force showed TC releases ranging from 40% to 70% of the drug loading. On the other hand, the tablets prepared using two tonnes of compression force showed a faster and more efficient TC release, between 60% and 90%. The presence of LIG in the tablets modified significantly the release profile and the maximum amount of TC released. Finally, a DPPH (2,2-diphenyl-1-picrylhydrozyl) assay was performed to confirm that the presence of LIG provided antioxidant properties to the formulations. Accordingly, LIG has potential as a pharmaceutical excipient.

Tablet Scoring: Current Practice, Fundamentals, and Knowledge Gaps

Oral solid dosage formulations and/or tablets have remained the preferred route of administration by both patients and health care practitioners. Oral tablets are easy to administer, they are non-invasive and cause less risk adversity. Because of the lack of commercially available tablet dose options, tablets are being split or partitioned by users. Tablet scoring refers to the breakage of a tablet to attain a desired efficacy dose and is an emerging concept in the pharmaceutical industry. The primary reason for the tablet scoring practice is to adjust the dose: dose tapering or dose titrating. Other reasons for tablet partitioning are to facilitate dose administration, particularly among the pediatric and the geriatric patient population, and to mitigating the high cost of prescription drugs. The scope of this review is to: (1) evaluate the advantages and inconveniences associated with tablet scoring/portioning, and (2) identify factors in the formulation and the manufacturing of tablets that influence tablet splitting. Whereas tablet partitioning has been a common practice, there is a lack of understanding regarding the fundamentals underpinning the performance of tablets with respect to splitting. Several factors can influence tablet partitioning: tablet size, shape, and thickness. A requirement has recently been set by the European Pharmacopoeia and the U.S. Food and Drug Administration for the uniformity of mass of subdivided tablets. For breaking ease, an in-vivo reference test and a routinely applicable in-vitro test need to be established.

Glibenclamide Mini-tablets with an Enhanced Pharmacokinetic and Pharmacodynamic Performance

In an attempt to decrease the dose, anticipated side effects, and the cost of production of glibenclamide, GLC, a potent oral hypoglycemic drug, the enhancement of the dissolution and hence the oral bioavailability were investigated. Adsorption and co-adsorption techniques using carriers having a very large surface area and surface active agents were utilized to enhance the drug dissolution. Moreover, the Langmuir adsorption isotherms were constructed to identify the type and mechanism of adsorption. The optimized formulation showing the highest in vitro release was compressed into mini-tablet to facilitate drug administration to elderly patients and those having swallowing difficulties. The produced mini-tablets were tested for their mechanical strength and in vitro release pattern. In addition, the pharmacodynamic and pharmacokinetic studies in New Zealand rabbits were performed using the optimized mini-tablet formulation. Mini-tablets containing GLC co-adsorbate with Pluronic F-68 and Laponite RD showed 100 ± 1.88% of GLC released after 20 min. Pharmacodynamic studies in rabbits revealed significantly higher (p ≤ 0.05) hypoglycemic effect with the optimized mini-tablets at a lower GLC dose compared to mini-tablets containing the commercial GLC dose. Moreover, pharmacokinetic analysis showed significantly higher (p ≤ 0.05) AUC, C_max, and shorter T_max. The optimized mini-tablet formulation showed 1.5-fold enhancement of the oral bioavailability compared to mini-tablets containing untreated GLC. It could be concluded that the co-adsorption technique successfully enhanced the oral bioavailability of GLC. Furthermore, the produced mini-tablets have a higher oral bioavailability with a lower GLC dose, which could offer economic benefit for industry as well as acceptability for patients.

Evaluation and Comparison of Three Types of Spray Dried Coprocessed Excipient Avicel® for Direct Compression

As coprocessed excipients (CPE) gain a lot of focus recently, this article compares three commercially available CPE of Avicel brand, namely, CE 15, DG, and HFE 102. Comparison is based on measured physical properties of coprocessed mixtures, respectively, flow properties, pycnometric density, mean particle size, specific surface area, moisture content, hygroscopicity, solubility, pH leaching, electrostatic charge, SEM images, and DSC. Tablets were made employing three pressure sets. Viscoelastic properties and ejection force were assessed during compression, as well as pycnometric density, mass uniformity, height, tensile strength, friability, disintegration, and wetting times. Avicel CE 15 is of mid-range flow properties, contains mid-size and nonspherical particles, and has high hygroscopicity, growing negative charge, best lubricity, lowest tensile strength, and mid-long disintegration times. Avicel DG possesses the worst flow properties, small asymmetrical particles, lowest hygroscopicity, stable charge, intermediate lubricity, and tensile strength and exhibits fast disintegration of tablets. Finally, Avicel HFE 102 has the best flow properties, large symmetrical particles, and middle hygroscopicity and its charge fluctuates throughout blending. It also exhibits inferior lubricity, the highest tensile strength, and slow disintegration of tablets. Generally, it is impossible to select the best CPE, as their different properties fit versatile needs of countless manufacturers and final products.

Effect of Moisture Content of Chitin-Calcium Silicate on Rate of Degradation of Cefotaxime Sodium

Assessment of incompatibilities between active pharmaceutical ingredient and pharmaceutical excipients is an important part of preformulation studies. The objective of the work was to assess the effect of moisture content of chitin calcium silicate of two size ranges (two specific surface areas) on the rate of degradation of cefotaxime sodium. The surface area of the excipient was determined using adsorption method. The effect of moisture content of a given size range on the stability of the drug was determined at 40°C in the solid state. The moisture content was determined at the beginning and the end of the kinetic study using TGA. The degradation in solution was studied for comparison. Increasing the moisture content of the excipient of size range 63-180 μm (surface area 7.2 m²/g) from 3.88 to 8.06% increased the rate of degradation of the drug more than two times (from 0.0317 to 0.0718 h^-1). While an opposite trend was observed for the excipient of size range < 63 μm (surface area 55.4 m²/g). The rate of degradation at moisture content < 3% was 0.4547 h^-1, almost two times higher than that (0.2594 h^-1) at moisture content of 8.54%, and the degradation in solid state at both moisture contents was higher than that in solution (0.0871 h^-1). In conclusion, the rate of degradation in solid should be studied taking into consideration the specific surface area and moisture content of the excipient at the storage condition and it may be higher than that in solution.

Development and Optimization of a Starch-Based Co-processed Excipient for Direct Compression Using Mixture Design

The development of novel excipients with enhanced functionality has been explored using particle engineering by co-processing. The aim of this study was to improve the functionality of tapioca starch (TS) for direct compression by co-processing with gelatin (GEL) and colloidal silicon dioxide (CSD) in optimized proportions. Design of Experiment (DoE) was employed to optimize the composition of the co-processed excipient using the desirability function and other supporting studies as a basis for selecting the optimized formulation. The co-processed excipient (SGS) was thereafter developed by the method of co-fusion. Flow and compaction studies of SGS were carried out in comparison to its parent component (TS) and physical mixture (SGS-PM). Tablets were prepared by direct compression (DC) containing ibuprofen (200 mg) as a model for poor compressibility using SGS, Prosolv®, and StarLac® as multifunctional excipients. The optimized composition of SGS corresponded to TS (90%), GEL (7.5%), and CSD (2.5%). The functionality of SGS was improved relative to SGS-PM in terms of flow and compression. Tablets produced with SGS were satisfactory and conformed to USP specifications for acceptable tablets. SGS performed better than Prosolv® in terms of disintegration and was superior to StarLac with respect to tensile strength and disintegration time. The application of DoE was successful in optimizing and developing a starch-based co-processed excipient that can be considered for direct compression tableting.

Development and Characterization of Multifunctional Directly Compressible Co-processed Excipient by Spray Drying Method

The present investigation was carried out to develop and characterize a multifunctional co-processed excipient for improving the compressibility of poorly compressible drugs. Etodolac was used as a model drug. Microcrystalline cellulose (MCC), lactose monohydrate (lactose), and StarCap 1500 (StarCap) were selected as components of the co-processed excipient. The spray drying method was used for co-processing of excipients. D-optimal mixture design was applied to optimize the proportion of component excipients. Statistical analysis of the D-optimal mixture design revealed that all response variables were significantly affected by the independent variables (p value < 0.05). Optimized composition was obtained from the desirability function. The optimized composition of the co-processed excipient was found to be 30% MCC, 25% lactose, and 45% StarCap. This optimized batch was evaluated for flow properties, compressibility parameters such as Kawakita's and Kuno's equation and Heckel's equation, and dilution potential. Evaluation parameters for flow properties (angle of repose, Carr's index, and Hausner's ratio) suggested excellent flow character. The parameters of Kawakita's and Kuno's equation and Heckel's equation suggested improvement in the compressibility of the model drug. Dilution potential was found to be 40%, and based on that, tablets of the model drug were formulated and evaluated for general evaluation parameters of tablets. All the parameters were found to be within the acceptance criteria which concluded that the multifunctional directly compressible co-processed excipient was prepared successfully that improved the compressibility of the poorly compressible model drug etodolac along with spray drying as an efficient method for the preparation of co-processed excipient.