Formulation of fast disintegrating tablets of ternary solid dispersions consisting of TPGS 1000 and HPMC 2910 or PVPVA 64 to improve the dissolution of the anti-HIV drug UC 781

Design of Experiment Approach for Enhancing the Dissolution Profile and Robustness of Loratadine Tablet Using D-α-Tocopheryl Polyethylene Glycol 1000 Succinate

Background: Formulating poorly water-soluble drugs poses significant challenges due to their limited solubility and bioavailability. Loratadine (LTD), classified as a BCS II molecule, exhibits notably low solubility, leading to reduced bioavailability. Objective: This study aims to enhance the dissolution rate of LTD through the utilization of the wet granulation process using Tocopheryl polyethylene glycol 1000 succinate (TPGS). Methods: A Design-of-Experiment methodology was adopted to investigate and optimize the formulation variables for preparing an oral delivery system of LTD with improved dissolution properties. The levels of TPGS (2-6% w/w), as a surfactant, and sodium starch glycolate (SSG; 2-8% w/w), as a super-disintegrant, were established as independent variables in the formulations. Loratadine was granulated in the presence of TPGS, and the resultant granules were subsequently compressed into tablets. The granules and tablets produced were then subjected to characterization. Results: ANOVA analysis indicated that both TPGS and SSG had a significant (p < 0.05) influence on the critical characteristics of the obtained granules and tablets, with TPGS showing a particularly notable effect. The optimal concentrations of TPGS and SSG for the development of LTD tablets with the necessary quality attributes were identified as 5.0% w/w and 2.0% w/w, respectively, through optimization utilizing the desirability function. The tablets produced at these optimized concentrations displayed favorable properties concerning their mechanical strength (5.72 ± 0.32 KP), disintegration time (7.11 ± 1.08 min.), and release profile (86.21 ± 1.61%). Conclusions: In conclusion, incorporating TPGS in the granulation process shows promise in improving the dissolution profile of poorly water-soluble drugs and demonstrated formulation robustness.

Colyophilized Sugar-Polymer Dispersions for Enhanced Processing and Storage Stability

Sucrose and trehalose pharmaceutical excipients are employed to stabilize protein therapeutics in a dried state. The mechanism of therapeutic protein stabilization is dependent on the sugars being present in an amorphous solid-state. Colyophilization of sugars with high glass transition polymers, polyvinylpyrrolidone (PVP), and poly(vinylpyrrolidone vinyl acetate) (PVPVA), enhances amorphous sugar stability. This study investigates the stability of colyophilized sugar-polymer systems in the frozen solution state, dried state postlyophilization, and upon exposure to elevated humidity. Binary systems of sucrose or trehalose with PVP or PVPVA were lyophilized with sugar/polymer ratios ranging from 2:8 to 8:2. Frozen sugar-PVPVA solutions exhibited a higher glass transition temperature of the maximally freeze-concentrated amorphous phase (Tg') compared to sugar-PVP solutions, despite the glass transition temperature (Tg) of PVPVA being lower than PVP. Tg values of all colyophilized systems were in a similar temperature range irrespective of polymer type. Greater hydrogen bonding between sugars and PVP and the lower hygroscopicity of PVPVA influenced polymer antiplasticization effects and the plasticization effects of residual water. Plasticization due to water sorption was investigated in a dynamic vapor sorption humidity ramping experiment. Lyophilized sucrose systems exhibited increased amorphous stability compared to trehalose upon exposure to the humidity. Recrystallization of trehalose was observed and stabilized by polymer addition. Lower concentrations of PVP inhibited trehalose recrystallization compared to PVPVA. These stabilizing effects were attributed to the increased hydrogen bonding between trehalose and PVP compared to trehalose and PVPVA. Overall, the study demonstrated how differences in polymer hygroscopicity and hydrogen bonding with sugars influence the stability of colyophilized amorphous dispersions. These insights into excipient solid-state stability are relevant to the development of stabilized biopharmaceutical solid-state formulations.

Development of Ternary Amorphous Solid Dispersions Manufactured by Hot-Melt Extrusion and Spray-Drying─Comparison of In Vitro and In Vivo Performance

Producing amorphous solid dispersions (ASDs) by hot-melt extrusion (HME) is favorable from an economic and ecological perspective but also limited to thermostable active pharmaceutical ingredients (APIs). A potential technology shift from spray-drying to hot-melt extrusion at later stages of drug product development is a desirable goal, however bearing the risk of insufficient comparability of the in vitro and in vivo performance of the final dosage form. Hot-melt extrusion was performed using API/polymer/surfactant mixtures with hydroxypropyl methylcellulose acetate succinate (HPMCAS) as the polymer and evaluated regarding the extrudability of binary and ternary amorphous solid dispersions (ASDs). Additionally, spray-dried ASDs were produced, and solid-state properties were compared to the melt-extruded ASDs. Tablets were manufactured of a ternary ASD lead candidate comparing their in vitro dissolution and in vivo performance. The extrudability of HPMCAS was improved by adding a surfactant as plasticizer, thereby lowering the high melt-viscosity. d-α-Tocopheryl polyethylene glycol succinate (TPGS) as surfactant showed the most similar solid-state properties between spray-dried and extruded ASDs compared to those of poloxamer 188 and sodium dodecyl sulfate. The addition of TPGS, however, barely affected API/polymer interactions. The in vitro dissolution experiment and in vivo dog study revealed a higher drug release of tablets manufactured from the spray-dried ASD compared to the melt-extruded ASD; this was attributed to the different particle size. We could further demonstrate that the drug release can be controlled by adjusting the particle size of melt-extruded ASDs leading to a similar release profile compared to tablets containing the spray-dried dispersion, which confirmed the feasibility of a technology shift from spray-drying to HME upon drug product development.

Review of industrially recognized polymers and manufacturing processes for amorphous solid dispersion based formulations

Evolving therapeutic landscape through combinatorial chemistry and high throughput screening have resulted in an increased number of poorly soluble drugs. Drug delivery strategies quickly adapted to convert these drugs into successful therapies. Amorphous solid dispersion (ASD) technology is widely employed as a drug delivery strategy by pharmaceutical industries to overcome the challenges associated with these poorly soluble drugs. The development of ASD formulation requires an understanding of polymers and manufacturing techniques. A review of US FDA-approved ASD-based products revealed that only a limited number of polymers and manufacturing technologies are employed by pharmaceutical industries. This review provides a comprehensive guide for the selection and overview of polymers and manufacturing technologies adopted by pharmaceutical industries for ASD formulation. The various employed polymers with their underlying mechanisms for solution-state and solid-state stability are discussed. ASD manufacturing techniques, primarily implemented by pharmaceutical industries for commercialization, are presented in Quality by Design (QbD) format. An overview of novel excipients and progress in manufacturing technologies are also discussed. This review provides insights to the researchers on the industrially accepted polymers and manufacturing technology for ASD formulation that has translated these challenging drugs into successful therapies.

Advances in the development of amorphous solid dispersions: The role of polymeric carriers

Amorphous solid dispersion (ASD) is one of the most effective approaches for delivering poorly soluble drugs. In ASDs, polymeric materials serve as the carriers in which the drugs are dispersed at the molecular level. To prepare the solid dispersions, there are many polymers with various physicochemical and thermochemical characteristics available for use in ASD formulations. Polymer selection is of great importance because it influences the stability, solubility and dissolution rates, manufacturing process, and bioavailability of the ASD. This review article provides a comprehensive overview of ASDs from the perspectives of physicochemical characteristics of polymers, formulation designs and preparation methods. Furthermore, considerations of safety and regulatory requirements along with the studies recommended for characterizing and evaluating polymeric carriers are briefly discussed.

Downstream processing of amorphous solid dispersions into orodispersible tablets

The formulation development of amorphous solid dispersions (ASDs) towards a patient-friendly oral solid dosage form is proving to be still challenging. To increase patient's compliance orodispersible tablets (ODTs) can be seen as promising alternative. Two different ASDs were prepared via hot melt extrusion (HME), using PVPVA as polymer for ritonavir (RTV) and HPMCAS for lopinavir (LPV). The extrudates were milled, sieved, and blended with Hisorad® (HRD) or Ludiflash® (LF), two established co-processed excipients (CPE) prior to tableting. Interestingly, the selected ASD particle size was pointed out to be a key parameter for a fast disintegration and high mechanical strength. In terms of PVPVA based ASDs, larger particle sizes > 500 µm enabled a rapid disintegration even under 30 s for 50 % ASD loaded ODTs, whereas the use of smaller particles went along with significant higher disintegration times. However, the influence of the CPE was immense for PVPVA based ASDs, since it was only possible to prepare well performing ODTs, when Hisorad® was chosen. In contrast for HPMCAS based ASDs the selection of smaller particle sizes 180-500 µm was beneficial for overcoming the poor compressibility of the ASD matrix polymer. ODTs with LPV could be produced using both CPEs even with higher ASD loads up to 75 %, while still showing remarkably fast disintegration.

Tablet Disintegration and Dispersion under In Vivo-like Hydrodynamic Conditions

Disintegration and dispersion are functional properties of tablets relevant for the desired API release. The standard disintegration test (SDT) described in different pharmacopoeias provides only limited information on these complex processes. It is considered not to be comparable to the biorelevant conditions due to the frequent occurrence of high hydrodynamic forces, among other reasons. In this study, 3D tomographic laser-induced fluorescence imaging (3D Tomo-LIF) is applied to analyse tablet disintegration and dispersion. Disintegration time (DT) and time-resolved particle size distribution in close proximity to the tablet are determined in a continuously operated flow channel, adjustable to very low fluid velocities. A case study on tablets of different porosity, which are composed of pharmaceutical polymers labelled with a fluorescent dye, a filler, and disintegrants, is presented to demonstrate the functionality and precision of the novel method. DT results from 3D Tomo-LIF are compared with results from the SDT, confirming the analytical limitations of the pharmacopoeial disintegration test. Results from the 3D Tomo-LIF method proved a strong impact of fluid velocity on disintegration and dispersion. Generally, shorter DTs were determined when cross-linked sodium carboxymethly cellulose (NaCMCXL) was used as disintegrant compared to polyvinyl polypyrrolidone (PVPP). Tablets containing Kollidon VA64 were found to disintegrate by surface erosion. The novel method provides an in-depth understanding of the functional behaviour of the tablet material, composition and structural properties under in vivo-like hydrodynamic forces regarding disintegration and the temporal progress of dispersion. We consider the 3D Tomo-LIF in vitro method to be of improved biorelevance in terms of hydrodynamic conditions in the human stomach.

Pulmonary Delivery of Reactive Oxygen Species/Glutathione-Responsive Paclitaxel Dimeric Nanoparticles Improved Therapeutic Indices against Metastatic Lung Cancer

Chemotherapeutics often failed to elicit optimal antitumor responses against lung cancer due to their limited exposure and accumulation in tumors. To achieve an effective therapeutic outcome of paclitaxel (PTX) against metastatic lung cancer with attenuated systemic and local toxicities, pulmonary delivery of redox-responsive PTX dimeric nanoparticles (NPs) was introduced. PTX dimers conjugated through variable lengths of diacid linkers containing disulfide bonds (-SS-) (i.e., α-PTX-SS-PTX, β-PTX-SS-PTX, and γ-PTX-SS-PTX) were initially synthesized and were subsequently self-assembled into uniform nanosized particles in the presence of vitamin E TPGS with high drug loading capacity (DE > 97%). Among various redox-sensitive scaffolds, β-PTX-SS-PTX NPs exhibited an optimal reactive oxygen species/glutathione-responsive drug release behavior, causing a lower local toxicity profile of PTX in the lungs. The scaffolds also demonstrated excellent colloidal stability, cellular uptake efficiency, and discriminating cytotoxicity between cancer and healthy cells. Further, they depicted an improved lung retention as compared to the control nanovesicles (β-PTX-CC-PTX) devoid of the redox-sensitive disulfide motif. In the B16F10 melanoma metastatic lung cancer mouse model, intratracheally delivered β-PTX-SS-PTX NPs exhibited a stronger anticancer potential with reduced systemic toxicity as compared to Taxol intravenous injection containing an equivalent PTX dose. The PTX dimeric NPs could also dramatically reduce the local toxicity relative to Taxol following their pulmonary delivery. Thus, this study presents redox-responsive PTX dimeric NPs as a promising nanomedicine for improved therapeutic efficacy against metastatic lung cancer.

Tablet formulation development focusing on the functional behaviour of water uptake and swelling

The functional behaviour of tablets is strongly influenced by their manufacturing process and the choice of excipients. Water uptake and swelling are prerequisites for tablet disintegration, dispersion and hence active pharmaceutical ingredient (API) dissolution. High proportions of polymeric excipients in tablets, which are typically used as API carriers in amorphous solid dispersions (ASDs), may be challenging due to the formation of a gelling polymer network (GPN). In this study, systematic investigations into the formulation development of tablets containing polymeric and other excipients are performed by water uptake and swelling analysis. The impact of tablet composition and porosity as well as pH of the test medium are investigated. The pH affects the analysis results for Eudragit L100-55 and Eudragit EPO. HPMC and Kollidon VA64 inhibit water uptake and swelling of tablets due to the formation of a GPN. High tablet porosity, coarse particle size of the polymer and the addition of fillers and disintegrants can reduce the negative impact of a GPN on tablet performance. The application of lubricants slows down the analysed processes. Water uptake and swelling data are fitted to an empirical model obtaining four characteristic parameters to facilitate the simple quantitative assessment of varying tablet formulations and structural properties.

Ternary solid dispersions: classification and formulation considerations

The number of active pharmaceutical compounds from the biopharmaceutical classification system (BCS) belonging to Class II and IV have significantly increased in recent years. These compounds have high therapeutic potential but are difficult to formulate as oral dosage forms due to their poor aqueous solubility. The solubility and bioavailability of these poorly water-soluble compounds can be increased by various formulation approaches, such as amorphous solid dispersions (ASD), salt formation, complexations, etc. Out of these techniques, the ASD approach, where compounds are converted into amorphous form and embedded in the hydrophilic matrix, have been successfully used in many marketed preparations. The recent advancement of this ASD approach is the design of ternary solid dispersions (TSD), where an additional component is added to further improve their performance in terms of solubility, stability, and processability. This review discusses the classification, mechanism of performance improvement, preparation techniques, and characterizations for TSD.

Fast-Dissolving Solid Dispersions for the Controlled Release of Poorly Watersoluble Drugs

Solid dispersions offer many advantages for oral drug delivery of poorly water-soluble drugs over other systems, including an increase in drug solubility and drug dissolution. An improvement in drug absorption and the higher bioavailability of active pharmaceutical ingredients in the gastrointestinal tract have been reported in various studies. In certain circumstances, a rapid pharmacological effect is required for patients. Fastdissolving solid dispersions provide an ideal formulation in such cases. This report will provide an overview of current studies on fast-dissolving solid dispersions, including not only solid dispersion powders with fast dissolution rates but also specific dose form for the controlled release of poorly water-soluble drugs. Specifically, the applications of fast-dissolving solid dispersions will be described in every specific case. Moreover, pharmaceutical approaches and the utilization of polymers will be summarized. The classification and analysis of fastdissolving solid dispersions could provide insight into strategies and potential applications in future drug delivery developments.

Development of Apremilast Solid Dispersion Using TPGS and PVPVA with Enhanced Solubility and Bioavailability

Apremilast (APST) is an effective inhibitor of phosphodieasterase 4 (PDE4) which is the first oral drug for the treatment of adult patients with active psoriatic arthritis. However, Apremilast's low solubility restricts its dissolution and bioavailability. In this study, APST solid dispersion with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and Poly(1-vinylpyrrolidone-co-vinyl acetate) (PVPVA) was developed to improve the dissolution and bioavailability of APST by spray drying. A series of TPGS were synthesized to elucidate the effect of the ratio of monoester to diester on solubilizing capacity. X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and Fourier transform infrared spectrophotometry (FT-IR) were used to characterize the solid dispersion, and the results showed that APST was amorphous in solid dispersion. In vitro dissolution study showed that the dissolution rate of solid dispersion in phosphate buffered saline (pH 6.8) was remarkably increased, reaching a release of 90% within 10 min. Moreover, in vivo pharmacokinetics study revealed that the bioavailability of solid dispersion in rats had significant improvement. In particular, its Cmax and AUClast were nearly 22- and 12.9-fold greater as compared to APST form B, respectively. In conclusion, APST solid dispersion with TPGS and PVPVA is an alternative drug delivery system to improve the solubility and oral bioavailability of APST.

A novel architecture for achieving high drug loading in amorphous spray dried dispersion tablets

Although Amorphous Solid Dispersions (ASDs) effectively increase bioavailability, tablet mass can be high due to the large fraction of excipients needed to stabilize the amorphous drug in the solid state, extend drug supersaturation in solution and achieve robust manufacturability. The aim of this work was to reduce tablet mass of an ASD tablet comprising a low glass transition temperature (Tg), rapidly crystallizing drug without compromising these key attributes. In this approach, erlotinib (Tg = 42 °C, Tm/Tg = 1.4 K/K) was spray dried with the high Tg polymer poly(methyl methacrylate-co-methacrylic acid) (Eudragit® L100, Evonik) (Tg = 187 °C) to facilitate high drug loading while maintaining physical stability. Hydroxypropyl methylcellulose acetate succinate (HPMCAS) (AQOAT® HF, Shin-Etsu) was granulated with the ASD to extend supersaturation in solution. For comparison, a benchmark ASD was spray dried at a lower drug loading with HPMCAS-H (Tg = 119 °C). This High Loaded Dosage Form (HLDF) approach reduced tablet mass by 40%, demonstrated similar physical stability and in vitro performance as the benchmark and exhibited excellent downstream manufacturability. Strategically combining two different polymers in a tablet to maintain physical stability and sustain supersaturation in solution can decrease tablet mass of some low Tg, rapidly crystallizing amorphous drugs.

Insoluble Polymers in Solid Dispersions for Improving Bioavailability of Poorly Water-Soluble Drugs

In recent decades, solid dispersions have been demonstrated as an effective approach for improving the bioavailability of poorly water-soluble drugs, as have solid dispersion techniques that include the application of nanotechnology. Many studies have reported on the ability to change drug crystallinity and molecular interactions to enhance the dissolution rate of solid dispersions using hydrophilic carriers. However, numerous studies have indicated that insoluble carriers are also promising excipients in solid dispersions. In this report, an overview of solid dispersion strategies involving insoluble carriers has been provided. In addition to the role of solubility and dissolution enhancement, the perspectives of the use of these polymers in controlled release solid dispersions have been classified and discussed. Moreover, the compatibility between methods and carriers and between drug and carrier is mentioned. In general, this report on solid dispersions using insoluble carriers could provide a specific approach and/or a selection of these polymers for further formulation development and clinical applications.

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

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

The Effect of Inorganic Salt on Disintegration of Tablets with High Loading of Amorphous Solid Dispersion Containing Copovidone

PURPOSE

While including amorphous solid dispersion (ASD) in tablet formulations is increasingly common, tablets containing high ASD loading are associated with slow disintegration, which presents a challenge to control pill burden for less potent compounds.

METHODS

We use a model ASD, composed of a hydrophobic drug with copovidone and a non-ionic surfactant, to explore formulation options that can prevent slow disintegration.

RESULTS

In addition to the ASD loading, the pH of the disintegration medium and the inclusion of inorganic salts in the tablet also have an impact on the tablet disintegration time. Certain kosmotropic salts, when added in the formulation, can significantly accelerate tablet disintegration, though the rank order in their effectiveness does not exactly follow the Hofmeister series at pH 1.8. The particle size and dissolution rate of the salt can contribute to its overall effectiveness.

CONCLUSION

We provided a mechanistic explanation of the disintegration process: fast-dissolving kosmotropic salt results in a concentrated salt solution inside the restrained tablet matrix, thus inhibiting the dissolution of copovidone and preventing polymer gelling which is the main cause leading the slow disintegration. The outcome of this study has enabled the design of a higher ASD loading platform formulation for copovidone based ASD. Graphical Abstract MicroCT aids the mechanistic understanding of the role of inorganic salt in the tablet disintegration of amorphous solid dispersion based formulation.

Investigation into Intermolecular Interactions and Phase Behavior of Binary and Ternary Amorphous Solid Dispersions of Ketoconazole

Conventionally, amorphous solid dispersions (ASDs) have been formulated as a binary matrix, but in recent years a new class of ASDs has emerged, where generally a second polymer is also added to the formulation. Having the presence of a second polymer necessitates a comprehensive solid-state characterization to study the intermolecular interactions and phase behavior on a molecular level. With this goal in mind, ketoconazole (KET) was selected as a model drug, and hydroxypropyl methyl cellulose (HPMC) and poly(acrylic acid) (PAA) were chosen as polymeric carriers. The binary and ternary ASDs were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and powder X-ray diffraction (PXRD). The binary KET:HPMC dispersions lacked any specific interactions, whereas binary KET:PAA dispersions and ternary KET:PAA:HPMC dispersions showed evidence for ionic and hydrogen bonding interactions. The ¹³C SSNMR deconvolution study established a comparison for molecular interactions between the binary KET:PAA and ternary KET:PAA:HPMC dispersions, with the binary KET:PAA system showing higher prevalence of ionic and hydrogen bonds than the ternary KET:PAA:HPMC system. Moreover, individual binary and ternary ASDs were found to be homogeneous on a nanometric level, implying the presence of a second polymer did not impact the phase homogeneity. In addition, a stronger interaction in binary KET:PAA and ternary KET:HPMC:PAA systems translated to better physical stability at different storage conditions. Through this case study it is recommended that a comprehensive investigation is needed to study the impact of using two polymers in ASD formulations in terms underlying intermolecular interactions and physical stability.

Modulation of Drug Crystallization and Molecular Interactions by Additives in Solid Dispersions for Improving Drug Bioavailability

Background::

An increase in poorly water-soluble drugs makes the design of drug delivery systems challenging.

Methods::

Currently, a number of prospective solid dispersions have been investigated with potential applications for delivering a variety of poorly water-soluble drugs. A number of traditional solid dispersions and modifiedsolid dispersions offer attractive advantages in the fabrication, design and development of those drugs for effective therapeutics.

Results::

Although traditional solid dispersions can produce a higher release rate, resulting in higher bioavailability compared to conventional dosage forms, this method is not always a promising approach. Modified-solid dispersion has demonstrated both the ability of its polymers to transform drug crystals into amorphous forms and molecular interactivity, thereby improving drug dissolution rate and bioavailability, especially with tough drugs. However, the classification of modified-solid dispersion, which guides the selection of the right strategy in solid dispersion preparation, remains ill-defined.

Conclusions::

This review focused on effective strategies in using additives in solid dispersion for improving drug bioavailability.

Insight into the Dissolution Molecular Mechanism of Ternary Solid Dispersions by Combined Experiments and Molecular Simulations

With the increase concern of solubilization for insoluble drug, ternary solid dispersion (SD) formulations developed more rapidly than binary systems. However, rational formulation design of ternary systems and their dissolution molecular mechanism were still under development. Current research aimed to develop the effective ternary formulations and investigate their molecular mechanism by integrated experimental and modeling techniques. Glipizide (GLI) was selected as the model drug and PEG was used as the solubilizing polymer, while surfactants (e.g., SDS or Tween80) were the third components. SD samples were prepared at different weight ratio by melting method. In the dissolution tests, the solubilization effect of ternary system with very small amount of surfactant (drug/PEG/surfactant 1/1/0.02) was similar with that of binary systems with high polymer ratios (drug/PEG 1/3 and 1/9). The molecular structure of ternary systems was characterized by differential scanning calorimetry (DSC), infrared absorption spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Moreover, molecular dynamic (MD) simulations mimicked the preparation process of SDs, and molecular motion in solvent revealed the dissolution mechanism of SD. As the Gordon-Taylor equation described, the experimental and calculated values of Tg were compared for ternary and binary systems, which confirmed good miscibility of GLI with other components. In summary, ternary SD systems could significantly decrease the usage of polymers than binary system. Molecular mechanism of dissolution for both binary and ternary solid dispersions was revealed by combined experiments and molecular modeling techniques. Our research provides a novel pathway for the further research of ternary solid dispersion formulations.

Formulation and clinical investigation of optimized vinpocetine lyoplant-tabs: new strategy in development of buccal solid dosage form

BACKGROUND

This work aimed to develop a new solid dosage formulation of vinpocetine (VPN) in the form of buccal freeze-dried pullulan-based tablets (lyoplant-tabs) loaded with physically modified drug binary system.

METHODS

Different polyvinyl pyrrolidone (PVP) grades were studied to prepare an efficient VPN binary system characterized by enhanced equilibrium saturation solubility, solubilization efficiency, thermodynamic stability, and permeation through oral mucosal cell lines. The concentrations of pullulan and swelling-aid polymer that affect the quality attributes of lyoplant-tabs were optimized. Clinical pharmacokinetics study on human volunteers for the optimized lyoplant-tabs compared to marketed product was accomplished.

RESULTS

A promising drug binary system with polyvinyl pyrrolidone vinyl acetate (PVP-VA64) utilizing the lyophilization technique was developed. Solid-state characterization confirmed transformation of VPN completely into the amorphous form. The concentrations of pullulan and swelling-aid polymer were significantly affecting the characteristics of the tablets. Compared to the commercial VPN tablets, pullulan-based buccal tablets demonstrated enhancement in the studied pharmacokinetic parameters with positive impact on the drug bioavailability.

CONCLUSION

These VPN lyoplant-tabs containing lyophilized PVP-VA64-VPN binary system can be considered as an alternative to currently available marketed tablets; however, further preclinical investigations using large number of volunteers are required.

A Repurposed Drug for Brain Cancer: Enhanced Atovaquone Amorphous Solid Dispersion by Combining a Spontaneously Emulsifying Component with a Polymer Carrier

Glioblastoma multiforme (GBM) is the most common and lethal central nervous system tumor. Recently, atovaquone has shown inhibition of signal transducer and activator transcription 3, a promising target for GBM therapy. However, it is currently unable to achieve therapeutic drug concentrations in the brain with the currently reported and marketed formulations. The present study sought to explore the efficacy of atovaquone against GBM as well as develop a formulation of atovaquone that would improve oral bioavailability, resulting in higher amounts of drug delivered to the brain. Atovaquone was formulated as an amorphous solid dispersion using an optimized formulation containing a polymer and a spontaneously emulsifying component (SEC) with greatly improved wetting, disintegration, dispersibility, and dissolution properties. Atovaquone demonstrated cytotoxicity against GBM cell lines as well as provided a confirmed target for atovaquone brain concentrations in in vitro cell viability studies. This new formulation approach was then assessed in a proof-of-concept in vivo exposure study. Based on these results, the enhanced amorphous solid dispersion is promising for providing therapeutically effective brain levels of atovaquone for the treatment of GBM.

Dissolution and precipitation behavior of ternary solid dispersions of ezetimibe in biorelevant media

The effects of different formulations and processes on inducing and maintaining the supersaturation of ternary solid dispersions of ezetimibe (EZ) in two biorelevant media fasted-state simulated intestinal fluid (FaSSIF) and fasted-state simulated gastric fluid (FaSSGF) at different temperatures (25 °C and 37 °C) were investigated in this work. Ternary solid dispersions of EZ were prepared by adding polymer PVP-K30 and surfactant poloxamer 188 using melt-quenching and spray-drying methods. The resulting solid dispersions were characterized using scanning electron microscopy, differential scanning calorimetry (DSC), modulated DSC, powder X-ray diffraction and Fourier transformation infrared spectroscopy. The dissolution of all the ternary solid dispersions was tested in vitro under non-sink conditions. All the prepared solid dispersions were amorphous in nature. In FaSSIF at 25 °C, the melt-quenched (MQ) solid dispersions of EZ were more soluble than the spray-dried (SD) solid dispersions and supersaturation was maintained. However, at 37 °C, rapid and variable precipitation behavior was observed for all the MQ and SD formulations. In FaSSGF, the melting method resulted in better solubility than the spray-drying method at both temperatures. Ternary solid dispersions show potential for improving solubility and supersaturation. However, powder dissolution experiments of these solid dispersions of EZ at 25 °C may not predict the supersaturation behavior at physiologically relevant temperatures.

Spray drying formulation of amorphous solid dispersions

Spray drying is a well-established manufacturing technique which can be used to formulate amorphous solid dispersions (ASDs) which is an effective strategy to deliver poorly water soluble drugs (PWSDs). However, the inherently complex nature of the spray drying process coupled with specific characteristics of ASDs makes it an interesting area to explore. Numerous diverse factors interact in an inter-dependent manner to determine the final product properties. This review discusses the basic background of ASDs, various formulation and process variables influencing the critical quality attributes (CQAs) of the ASDs and aspects of downstream processing. Also various aspects of spray drying such as instrumentation, thermodynamics, drying kinetics, particle formation process and scale-up challenges are included. Recent advances in the spray-based drying techniques are mentioned along with some future avenues where major research thrust is needed.

Nanofibers used for the delivery of analgesics

Nanofibers are extremely advantageous for drug delivery because of their high surface area-to-volume ratios, high porosities and 3D open porous structures. Local delivery of analgesics by using nanofibers allows site-specificity and requires a lower overall drug dosage with lower adverse side effects. Different analgesics have been loaded onto various nanofibers, including those that are natural, synthetic and copolymer, for various medical applications. Analgesics can also be singly or coaxially loaded onto nanofibers to enhance clinical applications. In particular, analgesic-eluting nanofibers provide additional benefits to preventing wound adhesion and scar formation. This paper reviews current research and breakthrough discoveries on the innovative application of analgesic-loaded nanofibers that will alter the clinical therapy of pain.

A New Extrudable Form of Hypromellose: AFFINISOL™ HPMC HME

Hypromellose is a hydrophilic polymer widely used in immediate- and modified-release oral pharmaceutical dosage forms. However, currently available grades of hypromellose are difficult, if not impossible, to process by hot melt extrusion (HME) because of their high glass transition temperature, high melt viscosity, and low degradation temperature. To overcome these challenges, a modified grade of hypromellose, AFFINISOL™ HPMC HME, was recently introduced. It has a significantly lower glass transition temperature and melt viscosity as compared to other available grades of hypromellose. The objective of this paper is to assess the extrudability and performance of AFFINISOL™ HPMC HME (100LV and 4M) as compared to other widely used polymers in HME, including HPMC 2910 100cP (the currently available hypromellose), Soluplus®, Kollidon® VA 64, and EUDRAGIT® E PO. Formulations containing polymer and carbamazepine (CBZ) were extruded on a co-rotating 16-mm twin-screw extruder, and the effect of temperature, screw speed, and feed rate was investigated. The performance of the solid dispersions was evaluated based on Flory-Huggins modeling and characterized by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and dissolution. All formulations extruded well except for HPMC 2910 100cP, which resulted in over-torqueing the extruder (machine overloading because the motor cannot provide efficient energy to rotate the shaft). Among the HME extrudates, only the EUDRAGIT® E PO formulation was crystalline as confirmed by DSC, XRD, and Raman, which agreed with predictions from Flory-Huggins modeling. Dissolution testing was conducted under both sink and non-sink conditions. Sink dissolution testing in neutral media revealed that amorphous CBZ in the HME extrudates completely dissolved within 15 min, which was much more rapid than the time for complete dissolution of bulk CBZ (60 min) and EUDRAGIT® E PO solid dispersion (more than 6 h). Non-sink dissolution in acidic media testing revealed that only CBZ contained in the AFFINISOL™ HPMC HME, and EUDRAGIT® E PO solid dispersions rapidly supersaturated after 15 min, reaching a twofold drug concentration compared to the CBZ equilibrium solubility. In summary, AFFINISOL™ HPMC HME 100LV and AFFINISOL™ HPMC HME 4M are useful in the pharmaceutical HME process to increase wetting and dissolution properties of poorly water-soluble drugs like CBZ.

Challenges and Strategies in Thermal Processing of Amorphous Solid Dispersions: A Review

Thermal processing of amorphous solid dispersions continues to gain interest in the pharmaceutical industry, as evident by several recently approved commercial products. Still, a number of pharmaceutical polymer carriers exhibit thermal or viscoelastic limitations in thermal processing, especially at smaller scales. Additionally, active pharmaceutical ingredients with high melting points and/or that are thermally labile present their own specific challenges. This review will outline a number of formulation and process-driven strategies to enable thermal processing of challenging compositions. These include the use of traditional plasticizers and surfactants, temporary plasticizers utilizing sub- or supercritical carbon dioxide, designer polymers tailored for hot-melt extrusion processing, and KinetiSol® Dispersing technology. Recent case studies of each strategy will be described along with potential benefits and limitations.

Dissolution Performance of High Drug Loading Celecoxib Amorphous Solid Dispersions Formulated with Polymer Combinations

PURPOSE

The aims of this study were twofold. First, to evaluate the effectiveness of selected polymers in inhibiting solution crystallization of celecoxib. Second, to compare the release rate and crystallization tendency of celecoxib amorphous solid dispersions (ASDs) formulated with a single polymer, or binary polymer combinations.

METHODS

The effectiveness of polymers, polyvinylpyrrolidone (PVP), hydroxypropylmethyl cellulose (HPMC) or HPMC acetate succinate (HPMCAS), in maintaining supersaturation of celecoxib solutions was evaluated by performing nucleation induction time measurements. Crystallization kinetics of ASD suspensions were monitored using Raman spectroscopy. Dissolution experiments were carried out under non-sink conditions.

RESULTS

Pure amorphous celecoxib crystallized rapidly through both matrix and solution pathways. Matrix and solution crystallization was inhibited when celecoxib was molecularly mixed with a polymer, resulting in release of the drug to form supersaturated solutions. Cellulosic polymers were more effective than PVP in maintaining supersaturation. Combining a cellulosic polymer and PVP enabled improved drug release and stability to crystallization.

CONCLUSIONS

Inclusion of an effective solution crystallization inhibitor as a minor component in ternary dispersions resulted in prolonged supersaturation following dissolution. This study shows the feasibility of formulation strategies for ASDs where a major polymer component is used to achieve one key property e.g. release, while a minor polymer component is added to prevent crystallization.

A novel bile salts-lipase polymeric film-infused minitablet system for enhanced oral delivery of cholecalciferol

Few researchers have investigated the use of multiple physiological enhancers combined with synthetic carriers to augment delivery of nutraceuticals. The current work describes the development of an oral delivery system termed a bioactive association platform (BAP) capable of delivering nutraceutical actives from a formulation framework specifically for enhancing the in vitro and in vivo performance of model vitamin, cholecalciferol (Vitamin D₃). Synthesis of a novel triple vitamin minitablet and an optimized bile salt/lipase alginate-glycerin film provided unique oral components for inclusion in a BAP capsule. Component validation and physicochemical characterizations included comparative ex vivo permeability, chemical structure mapping, thermodynamic analysis and magnetic resonance imaging. In vitro dissolution studies of the BAP produced an area under the dissolution curve (AUC) for cholecalciferol release that was 28% greater than a conventional comparator product. A total of 84.01% of cholecalciferol was released from the BAP within 3 h versus only 59% from a comparator. Ex vivo permeation studies revealed superior cholecalciferol membrane diffusion from the triple vitamin minitablet BAP component. In vivo performance showed a greater mean change from baseline cholecalciferol to peak plasma levels (C_max) from the BAP compared to the comparator (55.66 versus 46.05 ng/mL). Cholecalciferol bioavailability was improved in vivo with an AUC_0-inf from the BAP that was 3.2× greater than the conventional product. The BAP was also superior at improving and maintaining serum levels of the main metabolite, 25-hydroxyvitamin D₃, compared to the conventional system. In vitro and in vivo results thus confirmed improvements in cholecalciferol dissolution, membrane permeability and plasma drug levels. The study results position the BAP as an ideal oral vehicle for enhanced delivery of cholecalciferol.

Combinatorial delivery of Crizotinib-Palbociclib-Sildenafil using TPGS-PLA micelles for improved cancer treatment

The co-delivery of multiple chemotherapeutics by micellar delivery systems is a valuable approach to improve cancer treatment since various disease hallmarks can be targeted simultaneously. However, the delivery of multiple drugs requires a nanocarrier structure that can encapsulate various bioactive molecules. In this study, we evaluate the simultaneous encapsulation of a novel triple drug combination in D-α-tocopheryl polyethylene glycol 1000 succinate-poly(lactic acid) (TPGS-PLA) amphiphilic micelles for cancer therapy. The drug mixture involves two anti-tumoral drugs, Crizotinib and Palbociclib combined with Sildenafil, a compound that is capable of increasing drug accumulation in the intracellular compartment. Such combination aims to achieve an enhanced cytotoxic effect in cancer cells. Our results demonstrated that TPGS-PLA copolymers self-assembled into stable nanosized micelles (158.3nm) capable of co-encapsulating the three drugs with high loading efficiency. Triple drug loaded TPGS-PLA micelles were internalized in A549 non-small lung cancer cells and exhibited an improved cytotoxic effect in comparison with single (Crizotinib) or dual (Crizotinib-Palbociclib) drug loaded micelles, indicating the therapeutic potential of the triple co-delivery strategy. These findings demonstrate that TPGS-PLA micelles are suitable carriers for multiple drug delivery and also that this particular drug combination may have potential to improve cancer treatment.

Fast disintegrating crystalline solid dispersions of simvastatin for incorporation into orodispersible tablets

AIM

Spray dried solid dispersion (SDP) of crystalline simvastatin (SIM) in a fast disintegrating matrix of superdisintegrants was studied as a method to enhance SIM dispersibility, rheology, compactibility and compressibility for incorporation into orodispersible tablets (ODTs).

MATERIALS AND METHODS

The superdisintegrants investigated were crospovidone (CP), sodium starch glycollate (SSG) and calcium silicate (CS) were spray dried with simvastatin to form SDPs.

RESULTS

The SDPs were characterized and the median particle size of SDPs was similar or greater than the SIM, contributing to good rheology of SDPs, while the low bulk density of SDPs indicated a high compactibility. Interestingly electron micrographs for SDPs showed a CP or CS carrier coating of the SIM crystals, contributing to its rheology. Thermal analysis and X-ray diffraction confirmed that SIM was crystalline in the SDPs and no interaction between SIM and any of the carrier(s) was shown by Fourier transform-infra red. Drug content analysis showed a SIM content of 90-95% in SDPs containing CP or CS, while a higher SIM content of 143% was found in SDP containing SSG. When formulated as ODTs, blend containing SIM SDPs in CP showed ease of tableting, regardless of the turret speed. In comparison, tablet blend consisting of a physical mix (PM) of SIM and CP could only be tableted at the lower turret speed of 7 rpm. ODTs formulated using SIM SDPs in CP showed a higher extent of dissolution, compared to the ODTs containing corresponding PM or the commercially available SIM Zocor(®) tablets (ANOVA, P < 0.05).

CONCLUSION

SDP using disintegrants as carriers may offer an alternative formulation approach for ODTs of poorly soluble drugs.

The applications of Vitamin E TPGS in drug delivery

D-α-Tocopheryl polyethylene glycol 1000 succinate (simply TPGS or Vitamin E TPGS) is formed by the esterification of Vitamin E succinate with polyethylene glycol 1000. As novel nonionic surfactant, it exhibits amphipathic properties and can form stable micelles in aqueous vehicles at concentration as low as 0.02 wt%. It has been widely investigated for its emulsifying, dispersing, gelling, and solubilizing effects on poorly water-soluble drugs. It can also act as a P-glycoprotein (P-gp) inhibitor and has been served as an excipient for overcoming multidrug resistance (MDR) and for increasing the oral bioavailability of many anticancer drugs. Since TPGS has been approved by FDA as a safe pharmaceutic adjuvant, many TPGS-based drug delivery systems (DDS) have been developed. In this review, we discuss TPGS properties as a P-gp inhibitor, solubilizer/absorption and permeation enhancer in drug delivery and TPGS-related formulations such as nanocrystals, nanosuspensions, tablets/solid dispersions, adjuvant in vaccine systems, nutrition supplement, plasticizer of film, anticancer reagent and so on. This review will greatly impact and bring out new insights in the use of TPGS in DDS.

Solid dispersions of itraconazole for inhalation with enhanced dissolution, solubility and dispersion properties

The purpose of this study was to produce a dry powder for inhalation (DPI) of a poorly soluble active ingredient (itraconazole: ITZ) that would present an improved dissolution rate and enhanced solubility with good aerosolization properties. Solid dispersions of amorphous ITZ, mannitol and, when applicable, D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) were produced by spray-drying hydro-alcoholic solutions in which all agents were dissolved. These dry formulations were characterized in terms of their aerosol performances and their dissolution, solubility and physical properties. Modulate differential scanning calorimetry and X-ray powder diffraction analyses showed that ITZ recovered from the different spray-dried solutions was in an amorphous state and that mannitol was crystalline. The inlet drying temperature and, indirectly, the outlet temperature selected during the spray-drying were critical parameters. The outlet temperature should be below the ITZ glass transition temperature to avoid severe particle agglomeration. The formation of a solid dispersion between amorphous ITZ and mannitol allowed the dry powder to be produced with an improved dissolution rate, greater saturation solubility than bulk ITZ and good aerosol properties. The use of a polymeric surfactant (such as TPGS) was beneficial in terms of dissolution rate acceleration and solubility enhancement, but it also reduced aerosol performance. For example, significant dissolution rate acceleration (f(2)<50) and greater saturation solubility were obtained when introducing 1% (w/w) TPGS (mean dissolution time dropped from 50.4 min to 36.9 min and saturation solubility increased from 20 ± 3 ng/ml to 46 ± 2 ng/ml). However, the fine particle fraction dropped from 47 ± 2% to 37.2 ± 0.4%. This study showed that mannitol solid dispersions may provide an effective formulation type for producing DPIs of poorly soluble active ingredients, as exemplified by ITZ.

Perphenazine solid dispersions for orally fast-disintegrating tablets: physical stability and formulation

AIM

The aim of this study was to prepare an orally fast-disintegrating tablet (FDT) by direct compression, containing a poorly soluble drug (perphenazine, PPZ) formulated as a stable solid dispersion.

METHODS

The stability studies of the fast dissolving 5/1, 1/5, 1/20 (w/w), PPZ/polyvinylpyrrolidone K30 (PVP) or polyethylene glycol 8000 (PEG)) solid dispersions, and amorphous PPZ were conducted with differential scanning calorimetry, X-ray powder diffraction, Fourier-transform infrared spectroscopy, small-angle X-ray scattering, and dissolution rate studies.

RESULTS AND DISCUSSION

It was found that 1/5 PPZ/PEG was the most stable dispersion under elevated temperature and/or humidity. FDTs containing 60% of mannitol, 15% of calcium silicate, 15% of crospovidone, and 10% of 1/5 PPZ/PEG solid dispersion exhibited fast disintegration times (37 +/- 3), sufficient hardness (1.28 +/- 0.06 MPa), and fast onset of drug dissolution (34% of PPZ dissolved in 4 minutes), and these properties were found to be retained with storage. Thus, by optimizing the drug/excipient ratio of the solid dispersion and tablet composition, it was possible to produce FDTs that possessed fast disintegration and satisfactory drug dissolution in addition to adequate tensile strength, so that they can be handled and packed normally.