Manufacturing of solid dispersions of poorly water soluble drugs by spray drying: Formulation and process considerations

Pharmaceutical development of an oral tablet formulation containing a spray dried amorphous solid dispersion of docetaxel or paclitaxel

Previously, it was shown in Phase I clinical trials that solubility-limited oral absorption of docetaxel and paclitaxel can be drastically improved with a freeze dried solid dispersion (fdSD). These formulations, however, are unfavorable for further clinical research because of limitations in amorphicity of SD and scalability of the production process. To resolve this, a spray drying method for an SD (spSD) containing docetaxel or paclitaxel and subsequently drug products were developed. Highest saturation solubility (Smax), precipitation onset time (Tprecip), amorphicity, purity, residual solvents, yield/efficiency and powder flow of spSDs were studied. Drug products were monitored for purity/content and dissolution during 24 months at +15-25°C. Docetaxel spSD Smax was equal to that of fdSD but Tprecip was 3 times longer. Paclitaxel spSD Smax was 30% increased but Tprecip was equal to fdSD. spSDs were fully amorphous, >99% pure, <5% residual solvents, mean batch yield was 100g and 84%. spSDs had poor powder flow characteristics, which could not be resolved by changing settings, but by using 75% lactose as diluent. The drug product was a tablet with docetaxel or paclitaxel spSD and was stable for at least 24 months. Spray drying is feasible for the production of SD of docetaxel or paclitaxel for upcoming clinical trials.

Spray-dried amorphous isomalt and melibiose, two potential protein-stabilizing excipients

The possibility of producing amorphous isomalt and melibiose by spray drying was studied. The impact of process parameters on yield and solid-state stability was compared to sucrose and trehalose. All powders remained amorphous during 2-3 weeks. Processing was challenging due to powder stickiness. Low-temperature and low-humidity drying processes generally performed best. Most isomalt and sucrose powder was retrieved when using 60°C inlet temperature, 800L/h atomizing rate, 1.4ml/min feed rate, 15% concentration and 100% aspirator rate, giving 42-43°C outlet temperature. Isomalt was the most problematic, because it had the lowest Tg and became sticky very easily, therefore process parameters needed to be precisely balanced. There was more freedom in designing processes for melibiose but best yields were obtained with low-temperature (50°C inlet temperature, 800L/h atomizing rate, 4.9ml/min feed rate, 10% concentration and 100% aspirator, 39°C outlet temperature). Trehalose was different in that higher temperatures resulted in better yields. Yet, trehalose generally contained the highest moisture contents. The possibility to produce amorphous isomalt and melibiose at low-temperature process conditions makes them promising considering spray drying applications for heat-sensitive proteins. Melibiose is a better candidate than isomalt because of easier processability and superior solid-state stability.

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.

Amorphous solid dispersions: Rational selection of a manufacturing process

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

Evaluation of Three Amorphous Drug Delivery Technologies to Improve the Oral Absorption of Flubendazole

This study investigates 3 amorphous technologies to improve the dissolution rate and oral bioavailability of flubendazole (FLU). The selected approaches are (1) a standard spray-dried dispersion with hydroxypropylmethylcellulose (HPMC) E5 or polyvinylpyrrolidone-vinyl acetate 64, both with Vitamin E d-α-tocopheryl polyethylene glycol succinate; (2) a modified process spray-dried dispersion (MPSDD) with either HPMC E3 or hydroxypropylmethylcellulose acetate succinate (HPMCAS-M); and (3) confining FLU in ordered mesoporous silica (OMS). The physicochemical stability and in vitro release of optimized formulations were evaluated following 2 weeks of open conditions at 25°C/60% relative humidity (RH) and 40°C/75% RH. All formulations remained amorphous at 25°C/60% RH. Only the MPSDD formulation containing HPMCAS-M and 3/7 (wt./wt.) FLU/OMS did not crystallize following 40°C/75% RH exposure. The OMS and MPSDD formulations contained the lowest and highest amount of hydrolyzed degradant, respectively. All formulations were dosed to rats at 20 mg/kg in suspension. One FLU/OMS formulation was also dosed as a capsule blend. Plasma concentration profiles were determined following a single dose. In vivo findings show that the OMS capsule and suspension resulted in the overall highest area under the curve and C_max values, respectively. These results cross-evaluate various amorphous formulations and provide a link to enhanced biopharmaceutical performance.

Optimized Formulation of a Thermostable Spray-Dried Virus-Like Particle Vaccine against Human Papillomavirus

Existing vaccines against human papillomavirus (HPV) require continuous cold-chain storage. Previously, we developed a bacteriophage virus-like particle (VLP)-based vaccine for HPV infection, which elicits broadly neutralizing antibodies against diverse HPV types. Here, we formulated these VLPs into a thermostable dry powder using a multicomponent excipient system and by optimizing the spray-drying parameters using a half-factorial design approach. Dry-powder VLPs were stable after spray drying and after long-term storage at elevated temperatures. Immunization of mice with a single dose of reconstituted dry-powder VLPs that were stored at 37 °C for more than a year elicited high anti-L2 IgG antibody titers. Spray-dried thermostable, broadly protective L2 bacteriophage VLPs vaccine could be accessible to remote regions of the world (where ∼84% of cervical cancer patients reside) by eliminating the cold-chain requirement during transportation and storage.

Impact of polymer type on bioperformance and physical stability of hot melt extruded formulations of a poorly water soluble drug

Amorphous solid dispersion formulations have been widely used to enhance bioavailability of poorly soluble drugs. In these formulations, polymer is included to physically stabilize the amorphous drug by dispersing it in the polymeric carrier and thus forming a solid solution. The polymer can also maintain supersaturation and promote speciation during dissolution, thus enabling better absorption as compared to crystalline drug substance. In this paper, we report the use of hot melt extrusion (HME) to develop amorphous formulations of a poorly soluble compound (FaSSIF solubility=1μg/mL). The poor solubility of the compound and high dose (300mg) necessitated the use of amorphous formulation to achieve adequate bioperformance. The effect of using three different polymers (HPMCAS-HF, HPMCAS-LF and copovidone), on the dissolution, physical stability, and bioperformance of the formulations was demonstrated. In this particular case, HPMCAS-HF containing HME provided the highest bioavailability and also had better physical stability as compared to extrudates using HPMCAS-LF and copovidone. The data demonstrated that the polymer type can have significant impact on the formulation bioperformance and physical stability. Thus a thorough understanding of the polymer choice is imperative when designing an amorphous solid dispersion formulation, such that the formulation provides robust bioperformance and has adequate shelf life.

Evaluation of the Microcentrifuge Dissolution Method as a Tool for Spray-Dried Dispersion

Although using spray-dried dispersions (SDDs) to improve the bioavailability of poorly water-soluble compounds has become a common practice in supporting the early phases of clinical studies, their performance evaluation, whether in solid dosage forms or alone, still presents significant challenges. A microcentrifuge dissolution method has been reported to quickly assess the dissolution performance of SDDs. While the microcentrifuge dissolution method has been used in the SDD community, there is still a need to understand the mechanisms about the molecular species present in supernatant after centrifugation, the molecular nature of active pharmaceutical ingredients (APIs), as well as the impact of experimental conditions. In this paper, we aim to assess the effect of API and polymer properties on the dissolution behavior of SDDs along with centrifuging parameters, and for this, two poorly water-soluble compounds (indomethacin and ketoconazole) and two commonly used polymers in the pharmaceutical industry (PVP and HPMC-AS) were chosen to prepare SDDs. A typical microcentrifuge dissolution procedure as reported in the publication (Curatolo et al., Pharm Res 26:1419-1431, 2009) was followed. In addition, after separation of the supernatant from precipitation, some of the samples were filtered through filters of various sizes to investigate the particulate nature (particle size) of the supernatant. Furthermore, the centrifuge speed was varied to study sedimentation of API, SDD, or polymer particles. The results indicated that for the SDDs of four drug-polymer pairs, microcentrifuge dissolution exhibited varied behaviors, depending on the polymer and the drug used. The SDDs of indomethacin with either PVP or HPMC-AS showed a reproducible dissolution with minimum variability even after filtration and subjecting to varied centrifugation speed, suggesting that the supernatant behaved solution-like. However, ketoconazole-PVP and ketoconazole-HPMC-AS SDDs displayed a significant variation in concentration as the speed of centrifugation and the pore sizes of filters were altered, indicating that their supernatant was heterogeneous with the presence of particulates. In conclusion, microcentrifuge dissolution method was more suitable for indomethacin-PVP and indomethacin-HPMC-AS systems compared with ketoconazole-PVP and ketoconazole-HPMC-AS. Therefore, the use of microcentrifuge dissolution method depends on both compounds and polymers selected, which should be examined case by case.

Recent advances in the engineering of nanosized active pharmaceutical ingredients: Promises and challenges

The advances in the field of nanotechnology have revolutionized the field of delivery of poorly soluble active pharmaceutical ingredients (APIs). Nanosized formulations have been extensively investigated to achieve a rapid dissolution and therefore pharmacokinetic properties similar to those observed in solutions. The present review outlines the recent advances, promises and challenges of the engineering nanosized APIs. The principles, merits, demerits and applications of the current 'bottom-up' and 'top-down' technologies by which the state of the art nanosized APIs can be produced were described. Although the number of research reports on the nanoparticle engineering topic has been growing in the last decade, the challenge is to take numerous research outcomes and convert them into strategies for the development of marketable products.

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.

Development of Tablet Formulation of Amorphous Solid Dispersions Prepared by Hot Melt Extrusion Using Quality by Design Approach

The objective of the study was to identify the extragranular component requirements (level and type of excipients) to develop an immediate release tablet of solid dispersions prepared by hot melt extrusion (HME) process using commonly used HME polymers. Solid dispersions of compound X were prepared using polyvinyl pyrrolidone co-vinyl acetate 64 (PVP VA64), Soluplus, and hypromellose acetate succinate (HPMCAS-LF) polymers in 1:2 ratio by HME through 18 mm extruder. A mixture design was employed to study effect of type of polymer, filler (microcrystalline cellulose (MCC), lactose, and dicalcium phosphate anhydrous (DCPA)), and disintegrant (Crospovidone, croscarmellose sodium, and sodium starch glycolate (SSG)) as well as level of extrudates, filler, and disintegrant on tablet properties such as disintegration time (DT), tensile strength (TS), compactibility, and dissolution. Higher extrudate level resulted in longer DT and lower TS so 60-70% was the maximum amount of acceptable extrudate level in tablets. Fast disintegration was achieved with HPMCAS-containing tablets, whereas Soluplus- and PVP VA64-containing tablets had higher TS. Crospovidone and croscarmellose sodium were more suitable disintegrant than SSG to achieve short DT, and MCC was a suitable filler to prepare tablets with acceptable TS for each studied HME polymer. The influence of extragranular components on dissolution from tablets should be carefully evaluated while finalizing tablet composition, as it varies for each HME polymer. The developed statistical models identified suitable level of fillers and disintegrants for each studied HME polymer to achieve tablets with rapid DT (<15 min) and acceptable TS (≥1 MPa at 10-15% tablet porosity), and their predictivity was confirmed by conducting internal and external validation studies.

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions

Thermal processing technologies continue to gain interest in pharmaceutical manufacturing. However, the types and grades of polymers that can be utilized in common thermal processing technologies, such as hot-melt extrusion (HME), are often limited by thermal or rheological factors. The objectives of the present study were to compare and contrast two thermal processing methods, HME and KinetiSol® Dispersing (KSD), and investigate the influence of polymer type, polymer molecular weight, and drug loading on the ability to produce amorphous solid dispersions (ASDs) containing the model compound griseofulvin (GRIS). Dispersions were analyzed by a variety of imaging, solid-state, thermal, and solution-state techniques. Dispersions were prepared by both HME and KSD using polyvinylpyrrolidone (PVP) K17 or hydroxypropyl methylcellulose (HPMC) E5. Dispersions were only prepared by KSD using higher molecular weight grades of HPMC and PVP, as these could not be extruded under the conditions selected. Powder X-ray diffraction (PXRD) analysis showed that dispersions prepared by HME were amorphous at 10% and 20% drug load; however, it showed significant crystallinity at 40% drug load. PXRD analysis of KSD samples showed all formulations and drug loads to be amorphous with the exception of trace crystallinity seen in PVP K17 and PVP K30 samples at 40% drug load. These results were further supported by other analytical techniques. KSD produced amorphous dispersions at higher drug loads than could be prepared by HME, as well as with higher molecular weight polymers that were not processable by HME, due to its higher rate of shear and torque output.

Scalable preparation of silicon@graphite/carbon microspheres as high-performance lithium-ion battery anode materials

Silicon materials have received extensive research interest due to their high specific capacity of 3579 mA h g⁻¹and appropriate potential of approximately 0.4 Vvs.Li/Li⁺.

Optimization of Astaxanthin microencapsulation in hydrophilic carriers using response surface methodology

Astaxanthin (3, 3'-dihydroxy-β, β-carotene-4, 4'-dione; AST) belongs to class of xanthophylls and is very effective antioxidant. It has very poor aqueous solubility resulting in lower bioavailability which presents major concerns in product development for oral use. AST was microencapsulated with soluble polymers using spray drying to improve its solubility and bioavailability. Quality by Design (QbD), a widely used approach for prediction of quality for desired specifications and effects was applied Design of Experiments (DOE), a useful component of QbD was utilized to understand the effect of variables and their interactions. Different formulation variables like ratio of hydrophilic carriers, concentration of solubilizers and homogenizer speed were challenged in the experimental design during the process of microencapsulation. The optimized formulation showed consistent release rate and characterization was done by DSC, XRD and SEM study. Percent cell growth inhibition was increased in optimized formulation as compared to plain AST. This QbD study can form a basis for further development of poorly water soluble AST formulation by oral route with improved bioavailability on larger scale.

Optimization, physicochemical characterization and in vivo assessment of spray dried emulsion: A step toward bioavailability augmentation and gastric toxicity minimization

The limited solubility of BCS class II drugs diminishes their dissolution and thus reduces their bioavailability. Our aim in this study was to develop and optimize a spray dried emulsion containing indomethacin as a model for Class II drugs, Labrasol®/Transuctol® mixture as the oily phase, and maltodextrin as a solid carrier. The optimization was carried out using a 2(3) full factorial design based on two independent variables, the percentage of carrier and concentration of Poloxamer® 188. The effect of the studied parameters on the spray dried yield, loading efficiency and in vitro release were thoroughly investigated. Furthermore, physicochemical characterization of the optimized formulation was performed. In vivo bioavailability, ulcerogenic capability and histopathological features were assessed. The results obtained pointed out that poloxamer 188 concentration in the formulation was the predominant factor affecting the dissolution release, whereas the drug loading was driven by the carrier concentration added. Moreover, the yield demonstrated a drawback by increasing both independent variables studied. The optimized formulation presented a complete release within two minutes thus suggesting an immediate release pattern as well, the formulation revealed to be uniform spherical particles with an average size of 7.5μm entrapping the drug in its molecular state as demonstrated by the DSC and FTIR studies. The in vivo evaluation, demonstrated a 10-fold enhancement in bioavailability of the optimized formulation, with absence of ulcerogenic side effect compared to the marketed product. The results provided an evidence for the significance of spray dried emulsion as a leading strategy for improving the solubility and enhancing the bioavailability of class II drugs.

Solid-state characterization of Felodipine-Soluplus amorphous solid dispersions

The aim of the current study is to develop amorphous solid dispersion (SD) via hot melt extrusion technology to improve the solubility of a water-insoluble compound, felodipine (FEL). The solubility was dramatically increased by preparation of amorphous SDs via hot-melt extrusion with an amphiphilic polymer, Soluplus® (SOL). FEL was found to be miscible with SOL by calculating the solubility parameters. The solubility of FEL within SOL was determined to be in the range of 6.2-9.9% (w/w). Various techniques were applied to characterize the solid-state properties of the amorphous SDs. These included Fourier Transform Infrared Spectrometry spectroscopy and Raman spectroscopy to detect the formation of hydrogen bonding between the drug and the polymer. Scanning electron microscopy was performed to study the morphology of the SDs. Among all the hot-melt extrudates, FEL was found to be molecularly dispersed within the polymer matrix for the extrudates containing 10% drug, while few small crystals were detected in the 30 and 50% extrudates. In conclusion, solubility of FEL was enhanced while a homogeneous SD was achieved for 10% drug loading.

Effect of particle size on oral absorption of carvedilol nanosuspensions: in vitro and in vivo evaluation

The purpose of this work was to explore the particle size reduction effect of carvedilol on dissolution and absorption. Three suspensions containing different sized particles were prepared by antisolvent precipitation method or in combination with an ultrasonication process. The suspensions were characterized for particle size, surface morphology, and crystalline state. The crystalline form of carvedilol was changed into amorphous form after antisolvent precipitation. The dissolution rate of carvedilol was significantly accelerated by a reduction in particle size. The intestinal absorption of carvedilol nanosuspensions was greatly improved in comparison with microsuspensions and solution in the in situ single-pass perfusion experiment. The in vivo evaluation demonstrated that carvedilol nanosuspensions and microsuspensions exhibited markedly increased C_max (2.09- and 1.48-fold) and AUC_0−t (2.11- and 1.51-fold), and decreased T_max (0.34- and 0.48-fold) in contrast with carvedilol coarse suspensions. Moreover, carvedilol nanosuspensions showed good biocompatibility with the rat gastric mucosa in in vivo gastrointestinal irritation test. The entire results implicated that the dissolution rate and the oral absorption of carvedilol were significantly affected by the particle size. Particle size reduction to form nanosized particles was found to be an efficient method for improving the oral bioavailability of carvedilol.

Controlled Drug Delivery: Historical perspective for the next generation

The modern day drug delivery technology is only 60years old. During this period numerous drug delivery systems have been developed. The first generation (1950-1980) has been very productive in developing many oral and transdermal controlled release formulations for clinical applications. On the other hand, the second generation (1980-2010) has not been as successful in generating clinical products. This is in large part due to the nature of the problems to overcome. The first generation of drug delivery technologies dealt with physicochemical problems, while the second struggled with biological barriers. Controlled drug delivery systems can be made with controllable physicochemical properties, but they cannot overcome the biological barriers. The third generation (from 2010) drug delivery systems need to overcome both physicochemical and biological barriers. The physicochemical problems stem from poor water solubility of drugs, large molecular weight of peptide and protein drugs, and difficulty of controlling drug release kinetics. The biological barriers to overcome include distribution of drug delivery systems by the body rather than by formulation properties, limiting delivery to a specific target in the body. In addition, the body's reaction to formulations limits their functions in vivo. The prosperous future of drug delivery systems depends on whether new delivery systems can overcome limits set by human physiology, and the development process can be accelerated with new ways of thinking.

Wetting Kinetics: an Alternative Approach Towards Understanding the Enhanced Dissolution Rate for Amorphous Solid Dispersion of a Poorly Soluble Drug

Developing amorphous solid dispersions of water-insoluble molecules using polymeric materials is a well-defined approach to improve the dissolution rate and bioavailability. While the selected polymer plays a vital role in stabilizing the amorphous solid dispersion physically, it is equally important to improve the dissolution profile by inhibiting crystallization from the supersaturated solution generated by dissolution of the amorphous material. Furthermore, understanding the mechanism of dissolution rate enhancement is of vital importance. In this work, wetting kinetics was taken up as an alternative approach for understanding the enhanced dissolution rate for amorphous solid dispersion of a poorly soluble drug. While cilostazol (CIL) was selected as the model drug, povidone (PVP), copovidone, and hypromellose (HPMC) were the polymers of choice. The concentrations against time profiles were evaluated for the supersaturated solutions of CIL in the presence and absence of the selected polymers. The degree of supersaturation increased significantly with increase in polymer content within the solid dispersion. While povidone was found to maintain the highest level of supersaturation for the greatest length of time both in dissolution and solution crystallization experiments, copovidone and hypromellose were found to be the less effective as crystallization inhibitor. The ability of polymers to generate and maintain supersaturated drug solutions was assessed by dissolution studies. The wetting kinetics was compared against the solid dispersion composition to establish a correlation with enhanced dissolution rate.

Effect of hydrophilic additives on the dissolution and pharmacokinetic properties of itraconazole-enteric polymer hot-melt extruded amorphous solid dispersions

Hot-melt extrusion technology has been widely reported for producing amorphous solid dispersions of poorly water-soluble compounds. A number of studies revealed that enteric polymers containing ionizable groups are able to improve the physical stability and maintain drug supersaturation, thereby enhancing oral bioavailability. However, our previous studies found that itraconazole (ITZ)-enteric polymer amorphous solid dispersions are hydrophobic and poorly wettable. Moreover, drug release in an acidic environment (i.e. stomach) is very limited, indicating a narrow absorption window. In the present study, we investigated the effect of hydrophilic additives on the in vitro and in vivo performance of ITZ-enteric polymer amorphous solid dispersions. Incorporating Vitamin E TPGS into ITZ-HPMCAS amorphous solid dispersions significantly improved drug release in the acidic media. Surprisingly, a low concentration of Vitamin E TPGS also enhanced the degree of drug supersaturation in neutral pH media, which is unique as compared with other tested hydrophilic additives. This effect is not due to the solubilization of the surfactant. We further formulated the amorphous solid dispersions into tablet dosage forms and evaluated their performance in a bio-relevant dissolution media. Our optimized formulations exhibited drastically enhanced dissolution profiles as compared with the commercial ITZ product and ITZ amorphous solid dispersion without hydrophilic additive. In vivo study showed that Vitamin E TPGS induced rapid drug absorption after oral administration. Moreover, the elimination half-life of ITZ was prolonged due to the enzyme inhibition effect of Vitamin E TPGS.

Revealing facts behind spray dried solid dispersion technology used for solubility enhancement

Poor solubility and bioavailability of an existing or newly synthesized drug always pose challenge in the development of efficient pharmaceutical formulation. Numerous technologies can be used to improve the solubility and among them amorphous solid dispersion based spray drying technology can be successfully useful for development of product from lab scale to commercial scale with a wide range of powder characteristics. Current review deals with the importance of spray drying technology in drug delivery, basically for solubility and bioavailability enhancement. Role of additives, selection of polymer, effect of process and formulation parameters, scale up optimization, and IVIVC have been covered to gain the interest of readers about the technology. Design of experiment (DoE) to optimize the spray drying process has been covered in the review. A lot more research work is required to evaluate spray drying as a technology for screening the right polymer for solid dispersion, especially to overcome the issue related to drug re-crystallization and to achieve a stable product both in vitro and in vivo. Based on the recent FDA recommendation, the need of the hour is also to adopt Quality by Design approach in the manufacturing process to carefully optimize the spray drying technology for its smooth transfer from lab scale to commercial scale.

One-step production of darunavir solid dispersion nanoparticles coated with enteric polymers using electrospraying

Objectives

The aim of this work was to investigate the feasibility of producing darunavir (DRV) solid dispersion nanoparticles coated with an enteric polymer in one single step using electrospraying.

Methods

The core-shell nanoparticles were made using coaxial electrospraying. A solution of DRV with hydroxypropyl methylcellulose in a mixture of organic solvents formed the core, while the shell was produced from an enteric polymer (Eudragit L100) dissolved in an organic solvent. The final particles were evaluated in terms of morphology, physical state, encapsulation efficiency and in-vitro dissolution.

Key findings

Nanoparticles of encapsulated DRV solid dispersions within Eudragit L100 were successfully prepared with high encapsulation efficiency (90%). The enteric coating layer reduced the percentage of DRV release in acidic medium in the in-vitro dissolution test to less than 20%.

Conclusions

This study showed the potential of coaxial electrospraying for encapsulating solid dispersions within core-shell structured nanoparticles.

Mechanistic insight into the dramatic improvement of probucol dissolution in neutral solutions by solid dispersion in Eudragit E PO with saccharin

Objectives

Solid dispersion using Eudragit E PO (EPO) improves the dissolution of poorly water-soluble drugs in acidic solutions; however, the dissolution extremely decreases in neutral solutions. In this report, ternary solid dispersions containing probucol (PBC), EPO, and saccharin (SAC) were prepared to enable high drug dissolution at neutral pH.

Methods

Cryogenic-grinding was used to obtain ternary solid dispersions. Dissolution tests at neutral pH values were conducted to confirm the usefulness of the cryogenic-ground mixture (cryo-GM). The molecular state of each component and intermolecular interactions in the ternary cryo-GM were evaluated using powder X-ray diffraction (PXRD) and 13C solid-state NMR including spin-lattice relaxation time evaluation.

Key findings

PBC dispersed in ternary cryo-GM had an improved dissolution in neutral solutions. PBC and SAC were in amorphous states in EPO polymer matrices. The weak hydrophobic interaction between PBC and EPO and the ionic bond or hydrogen bond between EPO and SAC were demonstrated. These two molecular interactions improved the dissolution of PBC in neutral solutions.

Conclusion

Preparation of ternary solid dispersion is a potential method of improving drug solubility and absorption.

Combined application of mixture experimental design and artificial neural networks in the solid dispersion development

This study for the first time demonstrates combined application of mixture experimental design and artificial neural networks (ANNs) in the solid dispersions (SDs) development. Ternary carbamazepine-Soluplus®-poloxamer 188 SDs were prepared by solvent casting method to improve carbamazepine dissolution rate. The influence of the composition of prepared SDs on carbamazepine dissolution rate was evaluated using d-optimal mixture experimental design and multilayer perceptron ANNs. Physicochemical characterization proved the presence of the most stable carbamazepine polymorph III within the SD matrix. Ternary carbamazepine-Soluplus®-poloxamer 188 SDs significantly improved carbamazepine dissolution rate compared to pure drug. Models developed by ANNs and mixture experimental design well described the relationship between proportions of SD components and percentage of carbamazepine released after 10 (Q10) and 20 (Q20) min, wherein ANN model exhibit better predictability on test data set. Proportions of carbamazepine and poloxamer 188 exhibited the highest influence on carbamazepine release rate. The highest carbamazepine release rate was observed for SDs with the lowest proportions of carbamazepine and the highest proportions of poloxamer 188. ANNs and mixture experimental design can be used as powerful data modeling tools in the systematic development of SDs. Taking into account advantages and disadvantages of both techniques, their combined application should be encouraged.

Stabilisation of amorphous furosemide increases the oral drug bioavailability in rats

A glass solution of the amorphous sodium salt of furosemide (ASSF) and polyvinylpyrrolidone (PVP) (80:20 w/w%) was prepared by spray drying. It was investigated if PVP was able to stabilise ASSF during storage and dissolution and whether this influenced the in vivo performance of the glass solution after oral dosing to rats. The glass solution had a glass transition temperature of 121.3 ± 0.5°C, which was significantly higher than that of the pure drug (101.2°C). ASSF in the glass solution was stable for at least 168 days when stored at 20°C and 0% relative humidity. The glass solution exhibited fast dissolution in simulated intestinal medium, pH 6.5; the intrinsic dissolution rate was found to be 10.1 ± 0.6 mg/cm(2)/min, which was significantly faster than the pure ASSF. When investigating the stability during dissolution in stimulated intestinal medium at pH 6.5, the ASSF in the glass solution showed signs of crystallinity after 1 min of dissolution, but crystallised to a lesser extent than pure ASSF. The stabilising effect of PVP on ASSF, led to improved relative oral bioavailability in rats of 263%, when compared to the pure ASSF.