Evaluation of Hypromellose Acetate Succinate (HPMCAS) as a Carrier in Solid Dispersions

Colon-targeted delivery of niclosamide from solid dispersion employing a pH-dependent polymer via hotmelt extrusion for the treatment of ulcerative colitis in mice

Niclosamide (NCL) is repurposed to treat inflammatory bowel disease due to its anti-inflammatory properties and potential to reduce oxidative stress. This therapeutic activity remains challenging if administered directly due to its low solubility and high recrystallization tendency in gastric pH. Solid dispersions using pH-dependent polymer will be a better idea to improve the solubility, dissolution and targeted delivery at the colon. Hot melt extrusion was used to formulate a solid dispersion with 30% NCL utilising hydroxypropyl methylcellulose acetate succinate as a pH-dependent polymer. In vitro drug release studies revealed formulation (F1) containing 10%w/w Tween 80 showed minimal release (2.06%) at the end of 2 h, followed by 47.87% and 82.15% drug release at 6 h and 14 h, respectively, indicating the maximum amount of drug release in the colon. The drug release from the formulations containing no plasticiser and 5%w/w plasticiser was comparable to the pure crystalline drug (approximately 25%). Solid-state analysis confirmed particle conversion of crystalline NCL to amorphous form, and the optimised formulation was stable for 6 months without significant changes in dissolution profile. In contrast to pure NCL, the F1 formulation substantially reduced the disease activity index, colonic inflammation, histological alterations and oxidative damage in colitis mice. These findings reveal that the prepared formulation can potentially deliver the drug locally at the colon, making it an effective tool in treating ulcerative colitis.

Chemistry and Ionization of HPMCAS Influences the Dissolution and Solution-Mediated Crystallization of Posaconazole Amorphous Solid Dispersions

Hydroxypropyl methyl cellulose acetate succinate (HPMCAS) is one of the polymers of choice in formulating amorphous solid dispersions (ASDs) and helps to sustain high levels of drug supersaturation by delaying drug crystallization. Herein, the impact of HPMCAS chemistry on the solution crystallization kinetics of a fast-crystallizing lipophilic drug, posaconazole (PCZ), from the aqueous bulk phase and the drug-rich phase generated by liquid-liquid phase separation (LLPS), was studied. Three grades of HPMCAS: L, M, and H, which differ in the degree of acetyl and succinoyl substitution (A/S ratio), were compared. The influence of the polymers on the nucleation induction time, and LLPS concentration of PCZ, as well as the size, ζ-potential and composition of the nano-sized drug-rich phase was determined. An increase in the nucleation induction time was observed with an increase in the polymer A/S ratio. A blue shift in the fluorescence emission spectrum of PCZ suggested a greater extent of interaction between PCZ and HPMCAS with an increase in the A/S ratio. More polymer partitioning into the drug-rich phase was also observed with an increase in the A/S ratio, resulting in smaller droplets. A greater extent of ionization of HPMCAS upon increasing the pH from 5.5 to 7.5 decreased the hydrophobicity of the polymer resulting in shorter nucleation induction times. The phase behavior of PCZ in ASD release studies was consistent with these observations, where the shortest duration of supersaturation was observed with the L grade. Although the H grade provided the best inhibition of crystallization, complete release was only observed at higher pH. HPMCAS grade thus influences the kinetics of PCZ crystallization following release from an ASD, as well as the extent of release at physiologically relevant pH conditions. This study provides insights into the role of HPMCAS chemistry and ionization as factors influencing its ability to act as a crystallization inhibitor.

6-Carboxycellulose Acetate Butyrate: Effectiveness as an Amorphous Solid Dispersion Polymer

Amorphous solid dispersion (ASD) in a polymer matrix is a powerful method for enhancing the solubility and bioavailability of otherwise crystalline, poorly water-soluble drugs. 6-Carboxycellulose acetate butyrate (CCAB) is a relatively new commercial cellulose derivative that was introduced for use in waterborne coating applications. As CCAB is an amphiphilic, carboxyl-containing, high glass transition temperature (Tg) polymer, characteristics essential to excellent ASD polymer performance, we chose to explore its ASD potential. Structurally diverse drugs quercetin, ibuprofen, ritonavir, loratadine, and clarithromycin were dispersed in CCAB matrices. We evaluated the ability of CCAB to create ASDs with these drugs and its ability to provide solubility enhancement and effective drug release. CCAB/drug dispersions prepared by spray drying were amorphous up to 25 wt % drug, with loratadine remaining amorphous up to 50% drug. CCAB formulations with 10% drug proved effective at providing in vitro solubility enhancement for the crystalline flavonoid drug quercetin as well as ritonavir, but not for the more soluble APIs ibuprofen and clarithromycin and the more hydrophobic loratadine. CCAB did provide slow and controlled release of ibuprofen, offering a simple and promising Long-duration ibuprofen formulation. Formulation with clarithromycin showed the ability of the polymer to protect against degradation of the drug at stomach pH. Furthermore, CCAB ASDs with both loratadine and ibuprofen could be improved by the addition of the water-soluble polymer poly(vinylpyrrolidone) (PVP), with which CCAB shows good miscibility. CCAB provided solubility enhancement in some cases, and the slower drug release exhibited by CCAB, especially in the stomach, could be especially beneficial, for example, in formulations containing known stomach irritants like ibuprofen.

Exploring biorelevant conditions and release profiles of ritonavir from HPMCAS-based amorphous solid dispersions

Development of a release test for amorphous solid dispersions (ASDs) that is in vivo predictive is essential to identify optimally performing formulations early in development. For ASDs containing an enteric polymer, consideration of buffer properties is essential. Herein, release rates of hydroxypropyl methyl cellulose acetate succinate (HPMCAS) and ritonavir from ASDs with a 20% drug loading were compared in phosphate and bicarbonate buffers with different molarities, at pH 6.5. The bioaccessibility of ritonavir from the ASD in the tiny-TIM apparatus was also evaluated and compared to that of the crystalline drug. The surface pH at the dissolving solid: solution interface was evaluated using a pH-sensitive fluorescence probe for HPMCAS and ASD compacts in phosphate and bicarbonate buffers. Drug and polymer were found to release congruently in all buffer systems, indicating that the polymer controlled the drug release. Release was slowest in 10 mM bicarbonate buffer, and much faster in phosphate buffers with molarities typically used in release testing (20-50 mM). Release from the 10 mM bicarbonate buffer was matched in a 5 mM phosphate buffer. The surface pH of HPMCAS and HPMCAS:ritonavir ASDs was found to be lower than the bulk solution pH, where surface pH differences largely explained release rate differences seen in the different buffer systems. Ritonavir was highly bioaccessible from the ASD, as assessed by the tiny-TIM system, and much less bioaccessible when crystalline drug was used. The observations highlight the need for continued development of biorelevant assays tailored for ASD formulation assessment.

Microfluidics-on-a-chip for designing celecoxib-based amorphous solid dispersions: when the process shapes the product

The fundamental idea underlying the use of amorphous solid dispersions (ASDs) is to make the most of the solubility advantage of the amorphous form of a drug. However, the drug stability becomes compromised due to the higher free energy and disorder of molecular packing in the amorphous phase, leading to crystallization. Polymers are used as a matrix to form a stable homogeneous amorphous system to overcome the stability concern. The present work aims to design ASD-based formulations under the umbrella of quality by design principles for improving oral drug bioavailability, using celecoxib (CXB) as a model drug. ASDs were prepared from selected polymers and tested both individually and in combinations, using various manufacturing techniques: high-shear homogenization, high-pressure homogenization, microfluidics-on-a-chip, and spray drying. The resulting dispersions were further optimized, resorting to a 32 full-factorial design, considering the drug:polymers ratio and the total solid content as variables. The formulated products were evaluated regarding analytical centrifugation and the influence of the different polymers on the intrinsic dissolution rate of the CXB-ASDs. Microfluidics-on-a-chip led to the amorphous status of the formulation. The in vitro evaluation demonstrated a remarkable 26-fold enhancement in the intrinsic dissolution rate, and the translation of this formulation into tablets as the final dosage form is consistent with the observed performance enhancement. These findings are supported by ex vivo assays, which exhibited a two-fold increase in permeability compared to pure CXB. This study tackles the bioavailability hurdles encountered with diverse active compounds, offering insights into the development of more effective drug delivery platforms.

The interplay of poorly soluble drugs in dissolution from amorphous solid dispersions

In recent years, the application of fixed dose combinations of antiretroviral drugs in HIV therapy has been established. Despite numerous therapeutic benefits, this approach poses several challenges for the formulation development especially when poorly soluble drugs are considered. Amorphous solid dispersions (ASD) thereby have gained considerable interest in the pharmaceutical field, however, mainly including binary systems containing only one drug and a polymer. The co-formulation of two amorphous drugs can be accompanied by an immense increase in the complexity of the system as exemplarily reported for ritonavir and lopinavir embedded in a composite polymer matrix of PVPVA. The present study aims to present a new formulation approach to overcome the well-documented interaction during dissolution. Two different polymers, PVPVA and HPMCAS were used to produce ASDs for both drugs individually via hot-melt extrusion. The embedding of lopinavir in the slower dissolving polymer HPMCAS, while using PVPVA for ritonavir was found to significantly improve the overall dissolution performance compared to the individual use of PVPVA as well as to the commercial product Kaletra®. In addition, the use of different grades of HPMCAS demonstrated the possibility to further modify the dissolution profile. For a preliminary biorelevant assessment, the selected formulations were tested in a biphasic dissolution setup.

Supersaturable diacyl phospholipid dispersion for improving oral bioavailability of brick dust molecule: A case study of Aprepitant

This study aims to investigate the potential use of polymer inclusion in the phospholipid-based solid dispersion approach for augmenting the biopharmaceutical performance of Aprepitant (APT). Initially, different polymers were screened using the microarray plate method to assess their ability to inhibit drug precipitation in the supersaturated solution and HPMCAS outperformed the others. Later, the binary (BD) and ternary (TD) phospholipid dispersions were prepared using the co-solvent evaporation method. Solid-state characterization was performed using SEM and PXRD to examine the physical properties, while molecular interactions were probed through FTIR and NMR analysis. In vitro dissolution studies were performed in both fasted and fed state biorelevant media. The results demonstrated a substantial increase in drug release from BD and TD, approximately 4.8 and 9.9 times higher compared to crystalline APT in FaSSIF. Notably, TD also showed a lowered dissolution difference between fed and fasted states in comparison to crystalline APT, indicating a reduction in the positive food effect of APT. Moreover, we assessed the impact of polymer inclusion on permeation under in vitro biomimetic conditions. In comparison with the crystalline APT suspension, both BD and TD demonstrated approximately 3.3 times and 14 times higher steady-state flux (Jss values), respectively. This can be ascribed to the supersaturation and presence of drug-rich submicron particles (nanodroplets) along with the multiple aggregates of drug with phospholipids and polymer in the donor compartment, consequently resulting in a more substantial driving force for passive diffusion. Lastly, in vivo pharmacokinetic evaluation demonstrated the enhanced absorption of both TD and BD over the free drug suspension in the fasted state. This enhancement was evident through a 2.1-fold and 1.3-fold increase in Cmax and a 2.3-fold and 1.4-fold increase in AUC0-t, respectively. Overall, these findings emphasize the potential of polymer-based phospholipid dispersion in enhancing the overall biopharmaceutical performance of APT.

Comprehensive evaluation of polymer types and ratios in Spray-Dried Dispersions: Compaction, Dissolution, and physical stability

Amorphous solid dispersion (ASD) is a well-established strategy for enhancing the solubility and bioavailability of poorly soluble drugs. A significant portion of ASD products are in tablet form. However, the influence of common polymers and drug loading on the manufacturability of ASD tablets remains underexplored. This study focuses on investigating spray-dried ASDs from a tableting perspective by evaluating their physiochemical and mechanical properties. Itraconazole (ITZ) and indomethacin (IND), at the drug loadings ranging from 10% to 50%, were prepared with two polymers, hydroxypropyl methylcellulose acetate succinate (HPMCAS) and polyvinylpyrrolidone (PVP), serving as representative systems. Our findings revealed that increasing the drug loading resulted in a decreased surface area in ITZ-HPMCAS, IND-HPMCAS, and IND-PVP ASDs. However, this trend was not observed in ITZ-PVP dispersions, possibly due to the morphological disparities. Compaction results demonstrated that tabletability improved with decreasing drug loadings, except for ITZ-PVP dispersions. A partial least square analysis underscored particle surface area as the key factor influencing the tensile strength of ASD tablets. Additionally, our study disclosed that ITZ-PVP ASDs exhibited the worst release profiles and stability performance. The comprehensive journey from characterizing ASD particles to analyzing their compaction behavior and investigating drug release and physical stability offered profound insights into the attributes crucial for the downstream processing of amorphous pharmaceuticals.

Corrected solid-state 13 C nuclear magnetic resonance peak assignment and side-group quantification of hydroxypropyl methylcellulose acetyl succinate pharmaceutical excipients

Hydroxypropyl methylcellulose acetyl succinate (HPMCAS) is widely used as a pharmaceutical excipient, making a detailed understanding of its tunable structure important for formulation design. Several recently reported peak assignments in the solid-state 13 C NMR spectrum of HPMCAS have been corrected here using peak integrals in quantitative spectra, spectral editing, empirical chemical-shift predictions based on solution NMR, and full spectrum simulation analogous to deconvolution. Unlike in cellulose, the strong peak at 84 ppm must be assigned to C2 and C3 methyl ethers, instead of regular C4 of cellulose. The proposed assignment of signals at <65 ppm to OCH sites, including C5 of cellulose, could not be confirmed. CH2 spectral editing showed two resolved OCH2 bands, a more intense one from O-CH2 ethers of C6 at >69 ppm and a smaller one from its esters and possibly residual CH2 -OH groups, near 63 ppm. The strong intensities of resolved signals of acetyl, succinoyl, and oxypropyl substituents indicated the substitution of >85% of the OH groups in HPMCAS. The side-group concentrations in three different grades of HPMCAS were quantified.

Enhanced biopharmaceutical performance of brick dust molecule nilotinib via stabilized amorphous nanosuspension using a facile acid-base neutralization approach

"Brick dust" compounds have high lattice energy as manifested by the poor aqueous solubility and suboptimal bioavailability. Nilotinib being a weakly basic brick dust molecule exhibits erratic and limited absorption during gastrointestinal transit, attributed to pre-absorptive factors like pH-dependent solubility, poor dissolution kinetics, and post-absorptive factors including P-gp-mediated drug efflux. In our study, these problems are addressed holistically by the successful fabrication of amorphous nanosuspension by an acid-base neutralization approach. The nanosuspension was obtained via rapid precipitation of nilotinib in an amorphous form and the generated in situ sodium chloride salt assisted in stabilizing the drug-loaded nanosuspension in a cage of salt and micellar stabilizer. Soluplus® and hypromellose acetate succinate (HPMCAS) were employed as a novel combination of stabilizers. Systematic optimization was carried out by employing the I-optimal method using Design Expert® software with a concentration of HPMCAS and Soluplus® as independent variables and evaluating them for responses viz particle size, polydispersity index (PDI), and zeta potential. The resultant nanosuspension showed a mean particle size of 130.5 ± 1.22 nm with a PDI value of 0.27 ± 0.01, and a zeta potential of - 5.21 ± 0.91 mV. The nanosuspension was further characterized for morphology, dissolution, and in vivo pharmacokinetics study. X-ray powder diffraction study of the nano-formulation displayed a halo pattern revealing the amorphous form. Stability studies showed that the nanosuspension remained stable at 40 °C ± 2 °C and 75% RH ± 5% RH for a period of three months. In vitro drug release and solubility study showed threefold and 36-fold enhancement in dissolution and solubility of the nanosuspension. Furthermore, an in vivo pharmacokinetic study in Sprague-Dawley rats following oral administration displayed a 1.46-fold enhancement in the relative bioavailability of the nanosuspension in contrast to neat nilotinib.

Emerging Applications of Hydroxypropyl Methylcellulose Acetate Succinate: Different Aspects in Drug Delivery and Its Commercial Potential

Hydroxypropyl methylcellulose acetate succinate (HPMCAS) has multi-disciplinary applications spanning across the development of drug delivery systems, in 3D printing, and in tissue engineering, etc. HPMCAS helps in maintaining the drug in a super-saturated condition by inhibiting its precipitation, thereby increasing the rate and extent of dissolution in the aqueous media. HPMCAS has several distinctive characteristics, such as being amphiphilic in nature, having an ionization pH, and a succinyl and acetyl substitution ratio, all of which are beneficial while developing formulations. This review provides insights regarding the various types of formulations being developed using HPMCAS, including amorphous solid dispersion (ASD), amorphous nanoparticles, dry coating, and 3D printing, along with their applicability in drug delivery and biomedical fields. Furthermore, HPMCAS, compared with other carbohydrate polymers, shows several benefits in drug delivery, including proficiency in imparting stable ASD with a high dissolution rate, being easily processable, and enhancing bioavailability. The various commercially available formulations, regulatory considerations, and key patents containing the HPMCAS have been discussed in this review.

Development of Delayed Release Oral Formulation Comprising Esomeprazole Spray Dried Dispersion Utilizing Design of Experiment As An Optimization Strategy

Solid dispersion (SD) technology is one of the most widely preferred solubility enhancement methods, especially for Biopharmaceutics classification system class II and IV drugs. Since the last decade, its application for the dual purpose of solubility hike and modified release using novel carriers has been in demand for its added advantages. Spray drying is a commercially accepted technique with high aspects of scalability and product characteristics. The current study used spray-dried dispersion to design delayed release capsule for the proton pump inhibitor esomeprazole. The SD carrier hydroxypropyl methylcellulose acetate succinate-medium grade (HPMCAS-MF) enhanced solubility, inhibited precipitation of saturated drug solutions, and allowed enteric release owing to its solubility above pH 6. The proposed approach avoided compression, coating with enteric polymers, and the development of multi-particulate pellet-based formulations, improving manufacturing feasibility. The formulation was optimized using Box-Behnken design, considering significant formulation variables like HPMCAS-MF proportion and critical process parameters like feed flow rate and inlet temperature. The optimized spray-dried dispersion were characterized based on Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM) and also evaluated for solubility, in vitro drug release, residual solvent content, and stability testing. Response surface methodology optimization anticipated that formulation variables affected solubility and release profile, whereas CPPs affected yield. The design space was developed via overlay plot based on constraints specified to attain the desired response and validated using three checkpoint batches with desirability 1. FTIR showed active pharmaceutical ingredient-polymer compatibility. Particle size and SEM studies showed spherical particles with an average Z-value of 1.8 µ. DSC and PXRD confirmed SD's amorphous nature. The drug release investigation and release kinetics prediction utilizing DD-solver software showed a 2-h lag time with > 90% cumulative drug release up to 4 h for the DR formulation. ESM SDD were prepared by spray drying technique using the novel solid dispersion carrier HPMCAS-MF to serve the dual purpose of solubility enhancement and delayed release. The ratio of API:carrier and process variables like feed flow rate and inlet temperature were varied using the Box-Behnken Design to determine the design space of optimized product to procure the desired characteristics of solubility improvement compared to crystalline API and delayed release of PPI to avoid the degradation in the gastric environment. The developed formulation represents several benefits over the already existing marketed products.

Minimization of Acid-Catalyzed Degradation in KinetiSol Processing through HPMCAS Neutralization

Hypromellose acetate succinate (HPMCAS) is an enteric polymer that has been successfully employed as a carrier in amorphous solid dispersions (ASDs). Deprotonation of succinic acid substituents at intestinal pH levels results in solubilization of the polymer. However, the acidic moieties responsible for favorable pH-dependent solubility can also result in incompatibilities between acid-sensitive drugs and HPMCAS. Solution-state conversion of the carboxylic acid substituents of enteric polymers into carboxylate salts to reduce acid-mediated drug degradation is a demonstrated effective strategy for generating ASDs in enteric polymers. This work aimed to extend the use of a pre-ionized enteric polymer to KinetiSol solvent-free processing to reduce acid- or base-mediated drug degradation during processing. Pre-ionization of HPMCAS was accomplished by reaction with a stoichiometric quantity of sodium carbonate (Na₂CO₃) delivered as a saturated aqueous solution. The resulting ionized polymer, HPMCAS-Na, was dried thoroughly before processing. Tetrabenazine (TBZ) was chosen as a model drug for its susceptibility to degradation via both acid- and base-catalyzed reaction mechanisms and for its tendency to form a single impurity by these mechanisms. The use of HPMCAS-Na in KinetiSol solid dispersions (KSDs) of TBZ resulted in a 6- to 8-fold reduction of the acid- and base-generated TBZ impurity compared with KSDs formulated with untreated HPMCAS.

High-throughput kinetic turbidity analysis for determination of amorphous solubility and excipient screening for amorphous solid dispersions

Many poorly water-soluble active pharmaceutical ingredients (APIs) rely on supersaturating formulations, such as amorphous solid dispersions (ASDs), to enhance oral bioavailability. ASDs kinetically trap amorphous solid drugs within polymer excipient matrices to maintain the amorphous drug states. The maximum solution concentration of the API in these formulations is known as the amorphous solubility. In early drug development with scarce material and time, high-throughput approaches to measuring amorphous solubility and screening excipient effects on crystallization risk offer significant benefits to preclinical formulation scientists. Here, we developed a high-throughput screening (HTS) workflow to quantify amorphous solubility and screen ASD excipients by automated kinetic turbidity analysis. Testing 20 model APIs with a wide range of biorelevant solubility, we demonstrated their apparent amorphous solubility determined by the HTS approach strongly correlated with quantification results using conventional liquid chromatography; while the real-time analysis significantly saved analytical time and experimental efforts. Furthermore, kinetic turbidity profiles elucidated distinct excipient effects on the precipitation process of APIs. These results were successfully translated to dissolution and precipitation behaviors of ASD formulations composed of the tested polymers. The high-throughput kinetic turbidity workflow presents a facile and information-rich approach for amorphous solubility screenings against excipients, and helps guide enabling formulation development.

Investigation on the use of fused deposition modeling for the production of IR dosage forms containing Timapiprant

The present work focused on evaluating the feasibility of fused deposition modeling (FDM) in the development of a dosage form containing Timapiprant (TMP), also known as CHF6532, which is a novel active molecule indicated in the potential treatment of eosinophilic asthma upon oral administration. The resulting product could be an alternative, with potential towards personalization, of immediate release (IR) tablets used in the clinical studies. Formulations based on different polymeric carriers were screened, leading to the identification of a polyvinyl alcohol-based one, which turned out acceptable for versatility in terms of active ingredient content, printability and dissolution performance (i.e. capability to meet the dissolution specification set, envisaging >80% of the drug dissolved within 30 min). Following an in-depth evaluation on the influence of TMP solid state and of the voids volume resulting from printing on dissolution, few prototypes with shapes especially devised for therapy customization were successfully printed and were compliant with the dissolution specification set.

Designing synergistic crystallization inhibitors: Bile salt derivatives of cellulose with enhanced hydrophilicity

Crystallization inhibitors in amorphous solid dispersions (ASD) enable metastable supersaturated drug solutions that persist for a physiologically relevant time. Olefin cross-metathesis (CM) has successfully provided multifunctional cellulose-based derivatives as candidate ASD matrix polymers. In proof of concept studies, we prepared hydrophobic bile salt/cellulose adducts by CM with naturally occurring bile salts. We hypothesized that increased hydrophilicity would enhance the ability of these conjugates to maximize bioactive supersaturation. Their selective preparation presents a significant synthetic challenge, given polysaccharide reactivity and polysaccharide and bile salt complexity. We prepared such derivatives using a more hydrophilic hydroxypropyl cellulose (HPC) backbone, employing a pent-4-enyl tether (Pen) for appending bile acids. We probed structure-property relationships by varying the nature and degree of substitution of the bile acid substituent (lithocholic or deoxycholic acid). These conjugates are indeed synergistic inhibitors, as demonstrated with the fast-crystallizing prostate cancer drug, enzalutamide. The lithocholic acid methyl ester derivative, AcrMLC-PenHHPCPen (0.64), increased induction time 68 fold vs. drug alone.

Downstream Processing of Itraconazole:HPMCAS Amorphous Solid Dispersion: From Hot-Melt Extrudate to Tablet Using a Quality by Design Approach

The downstream processing of hot-melt extruded amorphous solid dispersions (ASDs) into tablets is challenging due to the low tabletability of milled ASDs. Typically, the extrudate strand is sized before milling, as the strand cannot be fed directly into the milling system. At the lab scale, the strand can be sized by hand-cutting before milling. For scaling up, pelletizers or chill roll and flaker systems can be used to break strands. Due to the different techniques used, differences in milling and tablet compaction are to be expected. We present a systematic study of the milling and tableting of an extruded ASD of itraconazole with hypromellose acetate succinate (HPMCAS) as a carrier polymer. The strand was sized using different techniques at the end of the extruder barrel (hand-cutting, pelletizer, or chill roll and flaker) before being milled at varying milling speeds with varying screen sizes. The effects of these variables (sizing technology, milling speed, and screen size) on the critical quality attributes (CQAs) of the milled ASD, such as yield, mean particle size (D50), tablet compaction characteristics, and tablet dissolution, were established using response surface methodology. It was found that the CQAs varied according to sizing technology, with chill roll flakes showing the highest percentage yield, the lowest D50, and the highest tabletability and dissolution rate for itraconazole. Pearson correlation coefficient tests indicated D50 as the most important CQA related to tabletability and dissolution. For certain milling conditions, the milling of hand-cut filaments results in similar particle size distributions (PSDs) to the milling of pellets or chill roll flakes.

Tablet Formulations of Polymeric Electrospun Fibers for the Controlled Release of Drugs with pH-Dependent Solubility

A challenge in the pharmaceutical sector is the development of controlled release dosage forms for oral administration of poorly soluble drugs, in particular, drugs characterized by pH-dependent solubility through the gastrointestinal tract, which itself shows wide variability in terms of environmental pHs. The best approach is to increase the dissolution rate of the drugs at the different pHs and only then modify its release behavior from the pharmaceutical form. This work aims to demonstrate the ability of properly designed polymeric nanofibers in enhancing the release rate of model drugs with different pH-dependent solubility in the different physiological pHs of the gastrointestinal tract. Polymeric nanofibers loaded with meloxicam and carvedilol were prepared using the electrospinning technique and were then included in properly designed tablet formulations to obtain fast or sustained release dosage forms. The nanofibers and the tablets were characterized for their morphological, physico-chemical and dissolution properties. The tablets are able to deliver the dose according to the expected release behavior, and zero-order, first-order, Higuchi, Korsmeyer–Peppas and Hixon–Crowell kinetics models were used to analyze the prevailing release mechanism of the tablets. This study shows that the electrospun fibers can be advantageously included in oral dosage forms to improve their release performances.

HPMCAS-Coated Alginate Microparticles Loaded with Ctx(Ile21)-Ha as a Promising Antimicrobial Agent against Salmonella Enteritidis in a Chicken Infection Model

Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) in poultry is most often transmitted by the fecal-oral route, which can be attributed to high population density. Upon encountering the innate immune response in a host, the pathogen triggers a stress response and virulence factors to help it survive in the host. The aim of this study was to evaluate the effect of hypromellose acetate/succinate (HPMCAS)-coated alginate microparticles containing the Ctx(Ile²¹)-Ha antimicrobial peptide (AMP) on both intestinal colonization and systemic infection of laying hens challenged with S. Enteritidis. The applied AMP microsystem reduced the bacterial load of S. Enteritidis in the liver, with a statistical significance between groups A (control, no Ctx(Ile²¹)-Ha peptide) and B (2.5 mg of Ctx(Ile²¹)-Ha/kg) at 2 days postinfection (dpi), potentially indicating the effectiveness of Ctx(Ile²¹)-Ha in the first stage of infection by S. Enteritidis. In addition, the results showed a significant decrease in the S. Enteritidis counts in the spleen and cecal content at 5 dpi; remarkably, no S. Enteritidis counts were observed in livers at 5, 7, and 14 dpi, regardless of the Ctx(Ile²¹)-Ha dosage (p-value <0.0001). Using the Chi-square test, the effect of AMP microparticles on S. Enteritidis fecal excretion was also evaluated, and a significantly lower bacterial excretion was observed over 21 days in groups B and C, in comparison with the untreated control (p-value <0.05). In summary, the use of HPMCAS-Ctx(Ile²¹)-Ha peptide microcapsules in laying hens drastically reduced the systemic infection of S. Enteritidis, mainly in the liver, indicating a potential for application as a feed additive against this pathogen.

Hot-melt extruded hydroxypropyl methylcellulose acetate succinate based amorphous solid dispersions: Impact of polymeric combinations on supersaturation kinetics and dissolution performance

Nucleation inhibition and maintenance of drug supersaturation over a prolonged period are desirable for improving oral absorption of amorphous solid dispersions. The present study investigates the impact of binary and ternary amorphous solid dispersions on the supersaturation kinetics of nifedipine using the polymers hydroxypropylmethylcellulose acetate succinate (HPMCAS) LG, and HG, Eudragit® RSPO, Eudragit® FS100, Kollidon® VA64 and Plasdone™ K-29/32. The amorphous solubility, nucleation induction time, and particle size analysis of nifedipine in a supersaturated solution were performed with and without the presence of polymers, alone or in combination. The HPMCAS-HG and HPMCAS-HG + LG combinations showed the highest nifedipine amorphous solubility of 169.47, 149.151 µg/mL, respectively and delay in nucleation induction time up to 120 min compared to other polymeric combinations. The solid dispersions prepared via hot melt extrusion showed the transformation of crystalline nifedipine to amorphous form. The in-vitro non-sink dissolution study revealed that although the binary nifedipine/HPMCAS-LG system had shown the greater supersaturation concentration of 66.1 µg/mL but could not maintain a supersaturation level up to 360 min. A synergistic effect emerged for ternary nifedipine/HPMCAS-LG/HPMCAS-HG, and nifedipine/HPMCAS-LG/Eudragit®FS100 systems maintained the supersaturation level with enhanced dissolution performance, demonstrating the potential of polymeric combinations for improved amorphous solid dispersion performance.

Polysaccharides as wall materials in spray-dried microencapsulation of bioactive compounds: Physicochemical properties and characterization

Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs.

Downstream processing of spray-dried ASD with hypromellose acetate succinate - Roller compaction and subsequent compression into high ASD load tablets

Despite wide commercial application of hypromellose acetate succinate (HPMCAS) in spray-dried amorphous solid dispersion (ASD) drug products, little information is available in the references on downstream processing of spray-dried dispersions with HPMCAS. Poor flow and high dilution factor are a challenge in formulating spray-dried ASDs into tablets, leaving little space for other excipients facilitating binding and disintegration. Direct compression is not possible due to the poor powder flow of spray-dried ASDs. Moisture has to be avoided due to the plasticizing properties of water on the ASD, resulting in reduced stability of the amorphous state. Thus, dry granulation by roller compaction and subsequent tablet compression is the preferred downstream process. We report the investigation of downstream processing by roller compaction and tablet compression of a high load formulation with 75% of spray-dried amorphous solid dispersion (Nifedipine:HPMCAS 1:2). A head to head comparison of microcrystalline cellulose/croscarmellose (MCC/cl-NaCMC) as binder/disintegrant vs. MCC and low-substituted hydroxypropyl cellulose (L-HPC) as excipient for binding and disintegration showed improved re-workability of the formulation with MCC/L-HPC after roller compaction. Upon transfer to the rotary press, a 45% higher tensile strength of tablets is observed after dry granulation with MCC/L-HPC.

Effect of pH Modifiers on the Solubility, Dissolution Rate, and Stability of Telmisartan Solid Dispersions Produced by Hot-melt Extrusion Technology

The aim of the current study was to investigate the dual effect of an amorphous solid dispersion generated by hot melt extrusion and the addition of pH modifiers on the solubility and stability of telmisartan. Hydroxypropyl methylcellulose acetate succinate L grade was used as a polymeric carrier and recrystallization inhibitor, and meglumine, sodium carbonate, or Neusilin S2 were incorporated as pH modifiers to generate a desirable microenvironmental pH in the solid dispersions. Differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy were incorporated to obtain the solid-state characterizations of telmisartan, and the results confirm a partial transformation of telmisartan to an amorphous state. An in vitro release study revealed that the transformation of telmisartan to an amorphous material improved its dissolution rate by 2-fold compared to pure drug and by up to 5-fold with the incorporation of pH modifiers. Results of the stability studies demonstrated that the samples have no significant degradation under accelerated stability conditions at 40 °C/75% RH.

Polyelectrolyte Matrices in the Modulation of Intermolecular Electrostatic Interactions for Amorphous Solid Dispersions: A Comprehensive Review

Polyelectrolyte polymers have been widely used in the pharmaceutical field as excipients to facilitate various drug delivery systems. Polyelectrolytes have been used to modulate the electrostatic environment and enhance favorable interactions between the drug and the polymer in amorphous solid dispersions (ASDs) prepared mainly by hot-melt extrusion. Polyelectrolytes have been used alone, or in combination with nonionic polymers as interpolyelectrolyte complexes, or after the addition of small molecular additives. They were found to enhance physical stability by favoring stabilizing intermolecular interactions, as well as to exert an antiplasticizing effect. Moreover, they not only enhance drug dissolution, but they have also been used for maintaining supersaturation, especially in the case of weakly basic drugs that tend to precipitate in the intestine. Additional uses include controlled and/or targeted drug release with enhanced physical stability and ease of preparation via novel continuous processes. Polyelectrolyte matrices, used along with scalable manufacturing methods in accordance with green chemistry principles, emerge as an attractive viable alternative for the preparation of ASDs with improved physical stability and biopharmaceutic performance.

Drug-Polymer Interactions in Acetaminophen/Hydroxypropylmethylcellulose Acetyl Succinate Amorphous Solid Dispersions Revealed by Multidimensional Multinuclear Solid-State NMR Spectroscopy

The bioavailability of insoluble crystalline active pharmaceutical ingredients (APIs) can be enhanced by formulation as amorphous solid dispersions (ASDs). One of the key factors of ASD stabilization is the formation of drug-polymer interactions at the molecular level. Here, we used a range of multidimensional and multinuclear nuclear magnetic resonance (NMR) experiments to identify these interactions in amorphous acetaminophen (paracetamol)/hydroxypropylmethylcellulose acetyl succinate (HPMC-AS) ASDs at various drug loadings. At low drug loading (<20 wt %), we showed that 1H-13C through-space heteronuclear correlation experiments identify proximity between aromatic protons in acetaminophen with cellulose backbone protons in HPMC-AS. We also show that 14N-1H heteronuclear multiple quantum coherence (HMQC) experiments are a powerful approach in probing spatial interactions in amorphous materials and establish the presence of hydrogen bonds (H-bond) between the amide nitrogen of acetaminophen with the cellulose ring methyl protons in these ASDs. In contrast, at higher drug loading (40 wt %), no acetaminophen/HPMC-AS spatial proximity was identified and domains of recrystallization of amorphous acetaminophen into its crystalline form I, the most thermodynamically stable polymorph, and form II are identified. These results provide atomic scale understanding of the interactions in the acetaminophen/HPMC-AS ASD occurring via H-bond interactions.

Interaction of Polymers with Enzalutamide Nanodroplets-Impact on Droplet Properties and Induction Times

Amorphous solid dispersions (ASDs), which consist of a drug dispersed in a polymeric matrix, are increasingly being applied to improve the in vivo performance of poorly water-soluble drugs delivered orally. The polymer is a critical component, playing several roles including facilitating drug release from the ASD, as well as delaying crystallization from the supersaturated solution generated upon dissolution. Certain ASD formulations dissolve to produce amorphous drug-rich nanodroplets. The interaction of the polymer with these nanodroplets is poorly understood but is thought to be important for inhibiting crystallization in these systems. In this study, the impact of ionic polymers on the crystallization kinetics of enzalutamide from supersaturated solutions containing different amounts of amorphous nanodroplets was evaluated by determination of nucleation induction times. The amount of the polymer associated with the drug nanodroplets was also determined. When comparing two polymers, hydroxypropylmethyl cellulose acetate succinate (HPMCAS) and Eudragit E PO, it was found that the crystallization tendency and physical properties of the drug nanodroplets varied in the presence of these two polymers. Both polymers distributed between the aqueous phase and the drug-rich nanodroplets. A greater amount of Eudragit E PO was associated with the drug-rich nanodroplets. Despite this, Eudragit E PO was a less-effective crystallization inhibitor than HPMCAS in systems containing nanodroplets. In conclusion, in supersaturated solutions containing amorphous nanodroplets, the extent of association of a polymer with the drug nanodroplet does not solely predict crystallization inhibition.

Leveraging bile solubilization of poorly water-soluble drugs by rational polymer selection

Poorly water-soluble drugs frequently solubilize into bile colloids and this natural mechanism is key for efficient bioavailability. We tested the impact of pharmaceutical polymers on this solubilization interplay using proton nuclear magnetic resonance spectroscopy, dynamic light scattering, and by assessing the flux across model membranes. Eudragit E, Soluplus, and a therapeutically used model polymer, Colesevelam, impacted the bile-colloidal geometry and molecular interaction. These polymer-induced changes reduced the flux of poorly water-soluble and bile interacting drugs (Perphenazine, Imatinib) but did not impact the flux of bile non-interacting Metoprolol. Non-bile interacting polymers (Kollidon VA 64, HPMC-AS) neither impacted the flux of colloid-interacting nor colloid-non-interacting drugs. These insights into the drug substance/polymer/bile colloid interplay potentially point towards a practical optimization parameter steering formulations to efficient bile-solubilization by rational polymer selection.

Solid state nuclear magnetic resonance studies of hydroxypropylmethylcellulose acetyl succinate polymer, a useful carrier in pharmaceutical solid dispersions

Hydroxypropylmethylcellulose (HPMC) acetyl succinate (HPMC-AS) is a key polymer used for the enablement of amorphous solid dispersions (ASDs) in oral solid dosage forms. Choice of the appropriate grade within the material is often made empirically by the manufacturer of small-scale formulations, followed by extensive real time stability. A key factor in understanding and predicting the performance of an ASD is related to the presence of hydrogen (or other) bonds between the polymer and active pharmaceutical ingredient (API), which will increase stability over the parameters captured by miscibility and predicted by the Gordon-Taylor equation. Solid state nuclear magnetic resonance (NMR) is particularly well equipped to probe spatial proximities, for example, between polymer and API; however, in the case of HPMC-AS, these interactions have been sometimes difficult to identity as the carbon-13 NMR spectra assignment is yet to be firmly established. Using feedstock, selectively substituted HPMC polymers, and NMR editing experiments, we propose here a comprehensive understanding of the chemical structure of HPMC-AS and a definitive spectral assignment of the ¹³ C NMR spectra of this polymer. The NMR data also capture the molar ratios of the acetate and succinate moieties present in HPMC-AS of various grades without the need for post treatment required by chromatography methods commonly use in pharmacopoeia. This knowledge will allow the prediction and measurement of interactions between polymers and APIs and therefore a rational choice of polymer grade to enhance the solid state stability of ASDs.

Characterization of Grades of HPMCAS Spray Dried Dispersions of Itraconazole Based on Supersaturation Kinetics and Molecular Interactions Impacting Formulation Performance

PURPOSE

The objective was to characterize hydroxypropyl methylcellulose acetate succinate (HMPCAS) grades L, M, and H to enhance itraconazole (ITZ) release and permeation from spray dried dispersions (SDDs), and to investigate underpinning molecular ITZ-HPMCAS interactions that differentiated grade performance.

METHODS

ITZ or its SDDs were subjected to solution stabilization assessment, one-dimensional proton nuclear magnetic resonance (NMR) spectroscopy, saturation transfer difference NMR studies, small volume dissolution, solid state transformation studies, and in vitro dissolution/permeation flux studies.

RESULTS

HPMCAS-L was the best performing grade overall and exhibited greatest ITZ supersaturation concentration, small volume dissolution, and in vitro dissolution/permeation flux. Meanwhile, H grade retarded ITZ precipitation to the greatest extent in solution stabilization studies and exhibited greater hydrophobic interaction with ITZ in NMR studies. However, this apparent advantage of H grade through hydrophobic interactions between drug-polymer appeared to limit overall dissolution/permeation performance of SDD.

CONCLUSIONS

In vitro SDD studies and drug-polymer interaction studies provided insight into the performance of HPMCAS grades, as well as the relative contributions of various mechanisms that polymer can promote ITZ absorption from SDD.

Polymer Selection for Hot-Melt Extrusion Coupled to Fused Deposition Modelling in Pharmaceutics

Three-dimensional (3D) printing offers the greatest potential to revolutionize the future of pharmaceutical manufacturing by overcoming challenges of conventional pharmaceutical operations and focusing design and production of dosage forms on the patient’s needs. Of the many technologies available, fusion deposition modelling (FDM) is considered of the lowest cost and higher reproducibility and accessibility, offering clear advantages in drug delivery. FDM requires in-house production of filaments of drug-containing thermoplastic polymers by hot-melt extrusion (HME), and the prospect of connecting the two technologies has been under investigation. The ability to integrate HME and FDM and predict and tailor the filaments’ properties will extend the range of printable polymers/formulations. Hence, this work revises the properties of the most common pharmaceutical-grade polymers used and their effect on extrudability, printability, and printing outcome, providing suitable processing windows for different raw materials. As a result, formulation selection will be more straightforward (considering the characteristics of drug and desired dosage form or release profile) and the processes setup will be more expedite (avoiding or mitigating typical processing issues), thus guaranteeing the success of both HME and FDM. Relevant techniques used to characterize filaments and 3D-printed dosage forms as an essential component for the evaluation of the quality output are also presented.

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.

Hypromellose acetate succinate based amorphous solid dispersions via hot melt extrusion: Effect of drug physicochemical properties

In this study, the impact of drug and hydroxypropyl methylcellulose acetate succinate (HPMCAS) grades physicochemical properties on extrusion process, dissolution and stability of the hot melt extruded amorphous solid dispersions (ASDs) of nifedipine and efavirenz was investigated. Incorporation of drugs affected the extrusion temperature required for solid dispersion preparation. Differential scanning calorimetry and powder X-ray diffraction studies confirmed the amorphous conversion of the drugs in the prepared formulations. The amorphous nature of ASDs was unchanged after 3 months of stability testing at 40 °C and 75% relative humidity. The dissolution efficiency of the ASDs was dependent on the log P of the drug. The inhibitory effect of HPMCAS on drug precipitation was dependent on the hydrophobic interactions between drug and polymer, polymer grade, and dose of the drug. The dissolution efficiency and dissolution rate of the ASDs were dependent on the log P of the drug and solubility and hydrophilicity of the polymer grade respectively. The inhibitory effect of HPMCAS on drug precipitation was dependent on the hydrophobic interactions between drug and polymer, polymer grade, and the dissolution dose of the drug.

Electrosprayed Polymeric Nanospheres for Enhanced Solubility, Dissolution Rate, Oral Bioavailability and Antihyperlipidemic Activity of Bezafibrate

Background

Bezafibrate is a BCS class II drug as it presents very low solubility in water; therefore, its bioavailability after oral administration is very poor. The aim of this work was to enhance solubility and dissolution rate of bezafibrate in water in order to enhance its oral bioavailability.

Methods

Several formulations were prepared using PVP K30 and Cremophor ELP employing the solvent-evaporation method and the electrospraying technique. Solubility, release rate, bioavailability in male Sprague Dawley rats, and lipid profile attributes in Wistar rats were assessed in comparison with bezafibrate plain powder. Solid-state characterization was carried out using X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).

Results

All the formulations exerted positive effect towards the desired goal. In particular, the optimized formulation furnished about 14-fold enhanced solubility and 85.48 ± 10.16% drug was released in 10 min as compared with bezafibrate alone (4.06 ± 2.59%). The drug existed in the amorphous state in the prepared sample as confirmed by XRD and DSC, whilst no drug-excipient interactions were observed through FTIR analysis. Moreover, SEM revealed smooth-surfaced spherical particles of the optimized formulation. A 5.5-fold higher oral bioavailability was achieved with the optimized formulation in comparison with bezafibrate plain powder. Also, TG, LDL and TC were decreased, and HDL was increased considerably in HFD-treated rats.

Conclusion

The optimized formulation consisting of bezafibrate, PVP K30 and cremophor ELP (1/12/1.5, w/w/w) might be a capable drug delivery system for orally administering poorly water-soluble bezafibrate with improved bioavailability and antihyperlipidemic effects.

Fluoroquinolone Amorphous Polymeric Salts and Dispersions for Veterinary Uses

Enrofloxacin (ENRO) is a poorly soluble drug used in veterinary medicine. It differs from the more widely used fluoroquinolone ciprofloxacin (CIP) by the presence of an ethyl substituent on its piperazine amino group. While a number of recent studies have examined amorphous composite formulations of CIP, little research has been conducted with ENRO in this area. Therefore, the main purpose of this work was to produce amorphous solid dispersions (ASDs) of ENRO. The solid-state properties of these samples were investigated and compared to those of the equivalent CIP ASDs, and their water uptake behavior, solubility, dissolution, and antibacterial activity were assessed. Like CIP, X-ray amorphous solid dispersions were obtained when ENRO was ball milled with acidic polymers, whereas the use of neutral polymers resulted in semi-crystalline products. Proton transfer from the carboxylic acids of the polymers to the tertiary amine of ENRO’s piperazine group appears to occur in the ASDs, resulting in an ionic bond between the two components. Therefore, these ASDs can be referred to as amorphous polymeric salts (APSs). The glass transition temperatures of the APSs were significantly higher than that of ENRO, and they were also resistant to crystallization when exposed to high humidity levels. Greater concentrations were achieved with the APSs than the pure drug during solubility and dissolution studies, and this enhancement was sustained for the duration of the experiments. In addition, the antimicrobial activity of ENRO was not affected by APS formation, while the minimum inhibitory concentrations and minimum bactericidal concentrations obtained with the APS containing hydroxypropyl methylcellulose acetate succinate grade MG (HPMCAS-MG) were significantly lower than those of the pure drug. Therefore, APS formation is one method of improving the pharmaceutical properties of this drug.

Amorphous nanoparticles by self-assembly: processing for controlled release of hydrophobic molecules

More than 40% of newly developed drug molecules are highly hydrophobic and, thus, suffer from low bioavailability. Kinetically trapping the drug as a nanoparticle in an amorphous state enhances solubility. However, enhanced solubility can be compromised by subsequent recrystallization from the amorphous state during drying processes. We combine Flash NanoPrecipitation (FNP) to generate nanoparticles with spray-drying to produce stable solid powders. We demonstrate that the continuous nanofabrication platform for nanoparticle synthesis and recovery does not compromise the dissolution kinetics of the drug. Lumefantrine, an anti-malaria drug, is highly hydrophobic with low bioavailability. Increasing the bioavailability of lumefantrine has the potential to reduce the dose and number of required administrations per treatment, thus reducing cost and increasing patient compliance. The low melting temperature of lumefantrine (Tm = 130 °C) makes the drying of amorphous nanoparticles at elevated temperatures potentially problematic. Via FNP, we produced 200-400 nm nanoparticles using hydroxypropyl methylcellulose acetate succinate (HPMCAS), lecithin phospholipid, and zein protein stabilizers. Zein nanoparticles were spray-dried at 100 °C and 120 °C to study the effect of the drying temperature. For zein powders, at two hours the dissolution kinetics under fasted conditions reached 85% release for the 100 °C sample, but only 60% release for the 120 °C sample. Powder X-ray diffraction, differential scanning calorimetry, and solid state nuclear magnetic resonance indicate that the lumefantrine in the nanoparticle core is amorphous for samples spray-dried at 100 °C. Dissolution under fed state conditions showed similar release kinetics for both temperatures, with 90-95% release at two hours. Zein and HPMCAS nanoparticles spray-dried at 100 °C showed release profiles in fasted and fed state media that are identical to those of lyophilized samples, i.e. those dried at cryogenic conditions where no transformation to the crystalline state can occur. Thus, spray drying 30 °C below the melting transition of lumefantrine is sufficient to maintain the amorphous state. These inexpensive formulations have potential to be developed into future therapies for malaria, and the results also highlight the potential of combining FNP and spray-drying as a versatile platform to assemble and rapidly recover amorphous nanoparticles in a solid dosage form.

Recent Perspectives in Hot Melt Extrusion-Based Polymeric Formulations for Drug Delivery: Applications and Innovations

Hot melt extrusion (HME), a technology which mixing the advantages of solid dispersion technology and mechanical preparation, is accepted in varied applications in pharmaceutical formulations. When combined with other techniques, such as nanotechnique, three-dimensional printing, and co-extrusion, HME becomes much more multifunctional in the application of drug delivery. While in most cases, polymers employed in HME are responsible for the final property of products. The process of HME together with the selection of materials employed in HME were described briefly. In addition, the applications of HME in drug delivery and its currently status in the pharmaceutical field were also included. Some commercial products produced by HME have met the approval of FDA, indicating the commercial viability of this technique. Although showing great potential in pharmaceutical manufacturing, HME is still challenged by high temperature, shear force, and high input energy. Development of equipment, modifying the parameters, and optimization of polymeric formulations are needed for a safe, effective, and multifunctional hot melt extrusion drug delivery system. Also, wider range of combinations between HME and other techniques may provide guideline for developing multiple applications in drug delivery.

Designing an ADME liquid formulation with matching exposures to an amorphous dosage form

Amorphous Solid Dispersion (ASD) based formulations have been frequently used to improve the bioavailability of poorly water soluble drugs, however, common processes to produce ASDs are not feasible for Absorption, Distribution, Metabolism and Excretion (ADME) studies with radio-labeled Active Pharmaceutical Ingredients (API) due to the complications associated with radioactive material handling. Liquid formulations are routinely used to support the ADME studies, though bridging the bioperformance between a liquid formulation to the amorphous dosage form for poorly soluble compounds has not been well studied, and can be challenging due to the potentially rapid in vitro and in vivo recrystallization and precipitation. Here we report the development of a fit for purpose liquid formulation that could accommodate the radioactive API and provide comparable bioavailability relative to the amorphous formulation without the need for dose adjustment. A number of formulation approaches were explored and the prototype formulations were evaluated by dissolution and preclinical pharmacokinetic studies. A PolyEthylene Glycol 400 (PEG 400) based solution formulation impregnated with a polymer, HydroxyPropyl MethylCellulose Acetate Succinate-L (HPMCAS-L), was identified as the lead formulation. It was found that the bioavailability of the formulation can be compromised by the presence of undissolved crystalline seeds, and the inclusion of HPMCAS-L can mitigate this effect, as well as potentially facilitate the nanoparticle formation. During the study, it is also noted that although dissolution test is instrumental in the formulation development, the in vitro study over predicted the extent of in vivo precipitation for PEG 400 formulation containing no crystalline seeds.

A Combined Utilization of Plasdone-S630 and HPMCAS-HF in Ziprasidone Hydrochloride Solid Dispersion by Hot-Melt Extrusion to Enhance the Oral Bioavailability and No Food Effect

The purpose of this study was to research a novel combination of Plasdone-S630 and HPMCAS-HF as hot-melt carrier used in ziprasidone hydrochloride for enhanced oral bioavailability and dismissed food effect. Ziprasidone hydrochloride solid dispersion (ZH-SD) was prepared by hot-melt extrusion technique, and its optimized formulation was selected by the central composite design (CCD), which was characterized for powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), in vitro dissolution study, and stability study. Finally, the in vivo study in fasted/fed state was carried out in beagle dogs. Based on PXRD analysis, HME technique successfully dispersed ziprasidone with a low crystallinity hydrochloride form in the polymers. According to the analysis of FTIR, hydrogen bonds were formed between drug and polymers during the process of HME. Without any noticeable bulk, crystalline could be found from the micrograph of ZH-SD when analyzed the result of scanning electron microscope (SEM). Pharmacokinetics studies indicated that the bioavailability of ZH-SD formulation had no significant difference in fasted and fed state, and the C_max and AUC of ZH-SD were two fold higher than Zeldox® in fasted state. This result indicated that ziprasidone has achieved a desired oral bioavailability in fasted state and no food effect.

Cellulose based polymers in development of amorphous solid dispersions

Cellulose derivatives have gained immense popularity as stabilizers for amorphous solid dispersion owing to their diverse physicochemical properties. More than 20 amorphous solid dispersion-based products that have been approved for marketing consist of cellulose derivatives as stabilizers, thus highlighting their importance in generation of amorphous solid dispersions. These polymers offer numerous advantages like drug solubilization, crystallization inhibition and improvement in release patterns of drugs. Exploring their potential and exploiting their chemistry and pH responsive behaviour have led to the synthesis of new derivatives that has broadened the scope of the use of cellulose derivatives in amorphous formulation development. The present review aims to provide an overview of different mechanisms by which these cellulose derivatives inhibit the crystallization of drugs in the solid state and from supersaturated solution. A summary of different categories of cellulose derivatives along with the newly explored polymers has been provided. A special segment on strengths, weaknesses, opportunities, and threats (SWOT) analysis and critical quality attributes (CQAs) which affect the performance of the cellulose based amorphous solid dispersion will aid the researchers in identifying the major challenges in the development of cellulose based solid dispersion and serve as a guide for further formulation development.

Physical properties and solubility studies of Nifedipine-PEG 1450/HPMCAS-HF solid dispersions

Low-order high-energy nifedipine (NIF) solid dispersions (SDs) were generated by melt solvent amorphization with polyethylene glycol (PEG) 1450 and hypromellose acetate succinate (HPMCAS-HF) to increase NIF solubility while achieving acceptable physical stability. HPMCAS-HF was used as a crystallization inhibitor. Individual formulation components, their physical mixtures (PMs), and SDs were characterized by differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR). NIF solubility and percent crystallinity (PC) were determined at the initial time and after 5 days stored at 25 °C and 60% RH. FTIR indicated that hydrogen bonding was involved with the amorphization process. FTIR showed that NIF:HPMCAS-HF intermolecular interactions were weaker than NIF:PEG 1450 interactions. NIF:PEG 1450 SD solubilities were significantly higher than their PM counterparts (p < 0.0001). The solubilities of NIF:PEG 1450:HPMCAS-HF SDs were significantly higher than their corresponding NIF:PEG 1450 SDs (p < 0.0001-0.043). All the SD solubilities showed a statistically significant decrease (p < 0.0001) after storage for 5 days. SDs PC were statistically lower than their comparable PMs (p < 0.0001). The PCs of SDs with HPMCAS-HF were significantly lower than SDs not containing only PEG 1450. All SDs exhibited a significant increase in PC (p < 0.0001-0.0089) on storage. Thermogravimetric analysis results showed that HPMCAS-HF bound water at higher temperatures than PEG 1450 (p < 0.0001-0.0039). HPMCAS-HF slowed the crystallization process of SDs, although it did not completely inhibit NIF crystal growth.