Amorphous solid dispersions and nanocrystal technologies for poorly water-soluble drug delivery – An update

Analysis of the Dissolution Behavior of Theophylline and Its Cocrystal Using ATR-FTIR Spectroscopic Imaging

Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic imaging is a powerful tool to visualize the distribution of components, and it has been used to analyze drug release from tablets. In this work, ATR-FTIR spectroscopic imaging was applied for observing the dissolution of molecular crystals from tablet compacts. The IR spectra provided chemically specific information about the transformation of crystal structures during the dissolution experiments. Theophylline (TPL) anhydrate and its cocrystals were used as model systems of molecular crystals. The IR spectra during the dissolution of TPL revealed information about the crystal structure of TPL, which transformed from anhydrate to monohydrate in water. During a dissolution test of a model cocrystal system, it was suggested that an active pharmaceutical ingredient (API) and a coformer were dissolved in water simultaneously. The IR spectra that were acquired during the dissolution of a cocrystal tablet showed new spectral bands attributed to the API after 5 min. This suggested that the precipitation of API was observed during the dissolution experiment. Measurements from ATR-FTIR spectroscopic imaging can visualize the drug release from the tablet and determine the transformation of molecular crystals during their dissolution. These results will have an impact on clarifying the dissolution mechanism of molecular crystals.

Enhancing hepatoprotective action: oxyberberine amorphous solid dispersion system targeting TLR4

Oxyberberine (OBB) is a significant natural compound, with excellent hepatoprotective properties. However, the poor water solubility of OBB hinders its release and absorption thus resulting in low bioavailability. To overcome these drawbacks of OBB, amorphous spray-dried powders (ASDs) of OBB were formulated. The dissolution, characterizations, and pharmacokinetics of OBB-ASDs formulation were investigated, and its hepatoprotective action was disquisitive in the D-GalN/LPS-induced acute liver injury (ALI) mouse model. The characterizations of OBB-ASDs indicated that the crystalline form of OBB active pharmaceutical ingredients (API) was changed into an amorphous form in OBB-ASDs. More importantly, OBB-ASDs showed a higher bioavailability than OBB API. In addition, OBB-ASDs treatment restored abnormal histopathological changes, improved liver functions, and relieved hepatic inflammatory mediators and oxidative stress in ALI mice. The spray drying techniques produced an amorphous form of OBB, which could significantly enhance the bioavailability and exhibit excellent hepatoprotective effects, indicating that the OBB-ASDs can exhibit further potential in hepatoprotective drug delivery systems. Our results provide guidance for improving the bioavailability and pharmacological activities of other compounds, especially insoluble natural compounds. Meanwhile, the successful development of OBB-ASDs could shed new light on the research process of poorly soluble medicine.

Transformation of ABT-199 Nanocrystal Suspensions into a Redispersible Drug Product-Impact of Vacuum Drum Drying, Spray Drying and Tableting on Re-Nanodispersibility

The present study compared vacuum drum drying (VDD) and conventional spray drying (SD) for solidifying crystalline ABT-199 nanosuspensions into redispersible oral drug products. The aim was to optimize formulation compositions and process conditions to maintain nanoparticle size after tablet redispersion. The impact of drug load (22%, 33%, 44%) and type of drying protectant (mannitol, mannitol/trehalose mix (1:1), trehalose) on redispersibility and material powder properties were investigated. Moreover, compression analysis was performed assessing the influence of compaction pressure on primary nanocrystal redispersibility and tablet disintegration. Higher drug loads and lower drying protectant levels resulted in particle growth, confirming a drug load dependence on redispersibility behavior. Notably, all drying protectants showed similar protection properties at properly chosen drying process parameters (Tg-dependent), except when VDD was used for mannitol formulations. Differences between the applied drying processes were observed in terms of downstream processing and tabletability: mannitol-containing formulations solidified via VDD showed an improved processability compared to formulations with trehalose. In conclusion, VDD is a promising drying technique that offers advantageous downstream processability compared to SD and represents an attractive novel processing technology for the pharmaceutical industry. As demonstrated in the present study, VDD combines higher yields with a leaner manufacturing process flow. The improved bulk properties provide enhanced tabletability and enable direct compression.

Amelioration of tableting properties and dissolution rate of naproxen co-grinded with nicotinamide: preparation and characterization of co-grinded mixture

OBJECTIVE AND SIGNIFICANCE

Reducing the dimensions, when other additives are present, shows potential as a method to improve the dissolution and solubility of biopharmaceutical classification system class II drugs that have poor solubility. In this investigation, the process involved grinding naproxen with nicotinamide with the aim of improving solubility and the rate of dissolution.

METHODS

Naproxen was subjected to co-milling with urea, dimethylurea, and nicotinamide using a planetary ball mill for a duration of 90 min, maintaining a 1:1 molar ratio for the excipients (screening studies). The co-milled combinations, naproxen in its pure milled form, and a physical mixture were subjected to analysis using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and solubility assessment. The mixture displaying the highest solubility (naproxen-nicotinamide) was chosen for further investigation, involving testing for intrinsic dissolution rate (IDR) and Fourier-transform infrared spectroscopy (FTIR) after co-milling for both 90 and 480 min.

RESULTS AND CONCLUSION

The co-milled combination, denoted as S-3b and consisting of the most substantial ratio of nicotinamide to naproxen at 1:3, subjected to 480 min of milling, exhibited a remarkable 45-fold increase in solubility and a 9-fold increase in IDR. XRPD analysis of the co-milled samples demonstrated no amorphization, while SEM images portrayed the aggregates of naproxen with nicotinamide. FTIR outcomes negate the presence of any chemical interactions between the components. The co-milled sample exhibiting the highest solubility and IDR was used to create a tablet, which was then subjected to comprehensive evaluation for standard attributes. The results revealed improved compressibility and dissolution properties.

Enhanced Bioavailability and Reduced Variability of Dasatinib and Sorafenib with a Novel Amorphous Solid Dispersion Technology Platform

Despite clinical advances with protein kinase inhibitors (PKIs), oral administration of many PKIs is associated with highly variable plasma exposure and a narrow therapeutic window. We developed a novel hybrid nanoparticle-amorphous solid dispersion (ASD) technology platform consisting of an amorphous PKI embedded in a polymer matrix. The technology was used to manufacture immediate-release formulations of 2 tyrosine kinase inhibitors (TKIs), dasatinib and sorafenib. Our primary objective was to improve the absorption properties and reduce the pharmacokinetic (PK) variability of each TKI. The PKs of XS004 (dasatinib-ASD, 100 mg tablet) and XS005 (sorafenib-ASD, 2 × 50 mg capsules) were compared with their crystalline formulated reference drugs (140 mg of dasatinib-reference and 200 mg of sorafenib-reference). The in vitro biopharmaceutics of dasatinib-ASD and XS005-granulate showed sustained increased solubility in the pH range 1.2-8.0 compared to their crystalline references. In vivo, XS004 was bioequivalent at a 30% lower dose and showed increased absorption and bioavailability, with 2.1-4.8 times lower intra- and intersubject variability compared to the reference. XS005 had an increased absorption and bioavailability of 45% and 2.2-2.8 times lower variability, respectively, but it was not bioequivalent at the investigated dose level. Taken together, the formulation platform is suited to generate improved PKI formulations with consistent bioavailability and a reduced pH-dependent absorption process.

Crosslinked PVA-g-poly(AMPS) Nanogels for Enhanced Solubility and Dissolution of Ticagrelor: Synthesis, Characterization, and Toxicity Evaluation

In this study, we synthesized PVA-g-poly(AMPS) nanogels with the aim of enhancing the solubility and dissolution of ticagrelor (TGR). Ticagrelor, a noncompetitive, reversible P2Y12 receptor antagonist, is prescribed to treat acute coronary syndrome. Ticagrelor has restricted oral bioavailability (≈36%) because of its poor solubility and permeability. The free radical polymerization methodology was employed to synthesize nanogels with varied concentrations of poly(vinyl alcohol) (polymer), 2-acrylamido-2-methylpropanesulfonic acid (monomer), and N,N-methylene bis(acrylamide) (crosslinker). The prepared nanogels were analyzed by swelling studies, % drug entrapment efficiency (DEE), solubility studies, in vitro drug release studies, zeta sizer, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The optimized formulation (PA5) revealed a particle size of 45.86 nm, with a polydispersity index (PDI) of 0.41 and a %DEE of 85.1%. FTIR spectroscopy, XRD, and SEM confirmed the formation of crosslinked nanogels with amorphous and porous structures, and TGA/DSC proved their thermal stability. In vitro dissolution studies showed 99.91% drug release, and the ticagrelor solubility from the synthesized formulations was significantly improved up to 8.2-fold. All formulations followed the Korsmeyer-Peppas model with the Fickian diffusion as the release mechanism. The toxicity studies carried out on rats and the MTT assay on the Caco-2 cell line validated the biocompatibility of the nanogel formulations. The outcomes of the current study led to the conclusion that the PVA-g-poly(AMPS) nanogels synthesized by us could be used as dedicated pharmaceutical delivery systems to achieve enhanced solubility and dissolution of ticagrelor.

Advances in Nanotechnology for Enhancing the Solubility and Bioavailability of Poorly Soluble Drugs

This manuscript offers a comprehensive overview of nanotechnology's impact on the solubility and bioavailability of poorly soluble drugs, with a focus on BCS Class II and IV drugs. We explore various nanoscale drug delivery systems (NDDSs), including lipid-based, polymer-based, nanoemulsions, nanogels, and inorganic carriers. These systems offer improved drug efficacy, targeting, and reduced side effects. Emphasizing the crucial role of nanoparticle size and surface modifications, the review discusses the advancements in NDDSs for enhanced therapeutic outcomes. Challenges such as production cost and safety are acknowledged, yet the potential of NDDSs in transforming drug delivery methods is highlighted. This contribution underscores the importance of nanotechnology in pharmaceutical engineering, suggesting it as a significant advancement for medical applications and patient care.

Nanocrystal technologies in biomedical science: From the bench to the clinic

The pharmaceutical industry is grappling with a pressing crisis in drug development characterized by soaring R&D costs, setbacks in blockbuster drug development due to poor aqueous solubility, and patent-related limitations on newly approved molecules. To combat these challenges, diverse strategies have emerged to enhance the solubility and dissolution rates of Biopharmaceutics Classification System (BCS) II and IV drug molecules. Enter drug nanocrystals, a revolutionary nanotechnology-driven, carrier-free colloidal drug delivery system. This review provides a comprehensive insight into nanocrystal strategies, stabilizer selection criteria, preparation methods, advanced characterization techniques, the evolving nanocrystal technological landscape, current market options, and exciting clinical prospects for reshaping the future of pharmaceuticals.

Quercetin nanocrystals prepared using a microfluidic chip with improved in vitro dissolution

OBJECTIVE

In order to improve the dissolution property of quercetin (QCT), the quercetin nanocrystals (QNCs) were prepared in this study.

METHODS

QNCs were prepared by a 100 μm diameter Y-shape microfluidic channel. Some impact factors affecting the generation of QNCs such as concentration and flow rate were investigated. Furthermore, the fluid mixing in the microfluidic channel was simulated by fluid software.

RESULTS

XRPD and DSC analyses indicated that the prepared QNCs were amorphous. Stable QNCs with a particle size of 77.9 ± 3.63 nm and polydispersity index of 0.26 ± 0.02 were obtained. TEM showed that the as-prepared QNCs had a uniform spherical shape with an average particle size of about 100-300 nm. In the dissolution medium without cosolvent Tween -80, the dissolution of QCT was poor, its final accumulated dissolution was only 3.95%, while that of QNCs was 66%.

CONCLUSION

When QCT was changed to QNCs by microfluidic technology, its dissolution property could be obviously improved. Therefore, microfluidic technology as a new method to prepare nanocrystals has a good applying prospect in improving dissolution property for poorly water-soluble drugs.

The Use of Data Mining for Obtaining Deeper Insights into the Fabrication of Prednisolone-Loaded Chitosan Nanoparticles

The present work explores a data mining approach to study the fabrication of prednisolone-loaded chitosan nanoparticles and their properties. Eight PLC formulations were prepared using an automated adaptation of the antisolvent precipitation method. The PLCs were characterized using dynamic light scattering, infrared spectroscopy, and drug release studies. Results showed that that the effective diameter, loading capacity, encapsulation efficiency, zeta potential, and polydispersity of the PLCs were influenced by the concentration and molecular weight of chitosan. The drug release studies showed that PLCs exhibited significant dissolution enhancement compared to pure prednisolone crystals. Principal components analysis and partial least squares regression were applied to the infrared spectra and the DLS data to extract higher-order interactions and correlations between the critical quality attributes and the diameter of the PLCs. Principal components revealed that the spectra clustered according to the type of material, with PLCs forming a separate cluster from the raw materials and the physical mix. PLS was successful in predicting the ED of the PLCs from the FTIR spectra with R2 = 0.98 and RMSE = 27.18. The present work demonstrates that data mining techniques can be useful tools for obtaining deeper insights into the fabrication and properties of PLCs, and for optimizing their quality and performance. It also suggests that FTIR spectroscopy can be a rapid and non-destructive method for predicting the ED of PLCs.

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.

Screening of Organic Small Molecule Excipients on Ternary Solid Dispersions Based on Miscibility and Hydrogen Bonding Analysis: Experiments and Molecular Simulation

The preparation of solid dispersions by mixing insoluble drugs with polymers is the main way to improve the aqueous solubility of drugs. The introduction of organic small molecule excipients into binary solid dispersions is expected to further enhance drug solubility by regulating intermolecular hydrogen bonding within the system at the microscopic level. In this study, we used carbamazepine (CBZ) as the target drug and polyvinylpyrrolidone as the solid dispersion matrix and screened the third component from 13 organic small molecules with good miscibility in the solid dispersion based on the principle of similarity of solubility parameters. The hydrogen bonding parameters and dissociation Gibbs free energy of the 13 organic small molecule-CBZ dimer were calculated by quantum mechanical simulation, and the tryptophan (Try) was identified as the optimal third component of organic small molecule. The migration of CBZ in binary and ternary systems was also analyzed by molecular dynamics simulation. On this theoretical basis, the corresponding solid dispersions were prepared, characterized, and tested for solubility analysis, which verified that the drug solubility was stronger for the system with the addition of polar fractions and the Try was indeed the best third component of organic small molecule compound, which was consistent with the simulation predictions. This screening method may provide theoretical guidance for drug modification design and clinical studies.

The Impact of Various Poly(vinylpyrrolidone) Polymers on the Crystallization Process of Metronidazole

In this paper, we propose one-step synthetic strategies for obtaining well-defined linear and star-shaped polyvinylpyrrolidone (linPVP and starPVP). The produced macromolecules and a commercial PVP K30 with linear topology were investigated as potential matrices for suppressing metronidazole (MTZ) crystallization. Interestingly, during the formation of binary mixtures (BMs) containing different polymers and MTZ, we found that linear PVPs exhibit maximum miscibility with the drug at a 50:50 weight ratio (w/w), while the star-shaped polymer mixes with MTZ even at a 30:70 w/w. To explain these observations, comprehensive studies of MTZ-PVP formulations with various contents of both components were performed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. The obtained results clearly showed that the polymer's topology plays a significant role in the type of interactions occurring between the matrix and MTZ. Additionally, we established that for MTZ-PVP 50:50 and 75:25 w/w BMs, linear polymers have the most substantial impact on inhibiting the crystallization of API. The star-shaped macromolecule turned out to be the least effective in stabilizing amorphous MTZ at these polymer concentrations. Nevertheless, long-term structural investigations of the MTZ-starPVP 30:70 w/w system (which is not achievable for linear PVPs) demonstrated its complete amorphousness for over one month.

Improved Dissolution Properties of Co-amorphous Probucol with Atorvastatin Calcium Trihydrate Prepared by Spray-Drying

A co-amorphous model drug was prepared by the spray-drying (SD) of probucol (PC) and atorvastatin calcium trihydrate salt (ATO) as low water solubility and co-former components, respectively. The physicochemical properties of the prepared samples were characterized by powder X-ray diffraction (PXRD) analysis, thermal analysis, Fourier transform infrared spectroscopy (FTIR), and dissolution tests. Stability tests were also conducted under a stress environment of 40 °C and 75% relative humidity. The results of PXRD measurements and thermal analysis suggested that PC and ATO form a co-amorphous system by SD. Thermal analysis also indicated an endothermic peak that followed an exotherm in amorphous PC and a physical mixture (PM) of amorphous PC and ATO; however, no endothermic peak was detected in the co-amorphous system. The dissolution profiles for PC in the co-amorphous sample composed of PC and ATO were improved compared to those for raw PC crystals or the PM. Stability tests indicated that the co-amorphous material formed by PC and ATO can be stored for 35 d without crystallization, whereas amorphous PC became crystallized within a day. Therefore, co-amorphization of PC and ATO prepared by SD is considered to be a useful method to improve the solubility of PC in water.

Preparation, in vitro and in vivo evaluation of a novel mitiglinide microemulsions

This study aimed to prepare an o/w mitiglinide microemulsion (MTGME) to improve the drug solubility and bioavailability. The formulation of o/w MTGME was optimized by the solubility study of drug, pseudo-ternary phase diagram and Box-Behnken design successively. MTGME was characterized by dynamic laser light scattering (DLS), zeta potential and transmission electron microscopy (TEM), moreover, the storage stability, pharmacodynamics and pharmacokinetics were investigated. The optimal prescription for MTGME consisted of Maisine 35-1 (oil), Cremophor EL (surfactant) and propylene glycol (PG, cosurfactant). MTGME with a spherical dimension of 58.1 ± 5.86 nm was stable when stored at 4 °C for 3 months. The blood glucose levers (BGL) of diabetic mice were uniformly and significantly decreased by intragastric (i.g.) administration of 1-4 mg/kg MTGME, in which BGL (i.g. 4 mg/kg MTGME) was reduced by 69% during 24 h. The pharmacokinetics study of MTGME (i.g., 20 mg/kg) in Wistar rats showed higher plasma drug concentration (Cmax, 2.9 folds), larger area under curve (AUC, 4.6 folds) and oral bioavailability than those of MTG suspensions. Generally, the MTGME (o/w) showed good effect on controlling hyperglycemia. Therefore, microemulsion can be used as an effective oral drug delivery system to improve the bioavailability of MTG.

Fused Deposition Modelling 3D printing and solubility improvement of BCS II and IV active ingredients - A narrative review

In the field of pharmaceutical research and development, Fused Deposition Modelling (FDM) 3D printing (3DP) has aroused growing interest within the last ten years. The use of thermoplastic polymers, combined with the melting process of the raw materials, offers the possibility of manufacturing amorphous solid dispersions (ASDs). In the pharmaceutical industry, the formulation of an ASD is a widely used strategy to improve the solubility of poorly soluble drugs (classified by the Biopharmaceutical Classification System (BCS) as class II and IV). In this review, an analysis of studies that have developed a FDM printed form containing a BCS class II or IV active substance was performed. The focus has been placed on the evaluation of the solid state of the active molecules (crystalline or amorphous) and on the study of their dissolution profile. Thus, the aim of this work is to highlight the interest of FDM 3DP to induce the amorphisation phenomenon of Class II and IV active substances by forming an ASD, and as result improving their solubility.

Development and evaluation of the in vitro schistosomicidal activity of solid dispersions based on 2-(-5-bromo-1-H-indole-3-yl-methylene)-N-(naphthalene-1-ylhydrazine-carbothiamide

Among all the neglected diseases, schistosomiasis is considered the second most important parasitic infection after malaria. Praziquantel is the most widely used drug for this disease, but its exclusive use may result in the development of drug-resistant schistosomiasis. To increase the control of the disease, new drugs have been developed as alternative treatments, among them 2-(-5-bromo-1-h-indole-3-yl-methylene)-N-(naphthalene-1-ylhydrazine-carbothiamide (LQIT/LT-50), which showed promising schistosomicidal activity in nonclinical studies. However, LQIT/LT-50 presents low solubility in water, resulting in reduced bioavailability. To overcome this solubility problem, the present study aimed to develop LQIT/LT-50 solid dispersions for the treatment of schistosomiasis. Solid dispersions were prepared through the solvent method using Soluplus©, polyethylene glycol (PEG) or polyvinylpyrrolidone (PVP K-30) as hydrophilic carriers. The formulations with the best results in the compatibility tests, aqueous solubility and preliminary stability studies have undergone solubility tests and physicochemical characterizations by Fourier-transform infrared spectroscopy (FTIR), x-ray diffractometry (XRD), exploratory differential calorimetry (DSC), thermogravimetry (TG) and Raman spectroscopy. Finally, the schistosomicidal activity was evaluated in vitro. The phycochemical analyzes showed that when using PVP K-30, there was an interaction between the PVP K-30 and LQIT/LT-50, proving the successful development of the solid dispersion. Furthermore, an increase in the solubility of the new system was observed (LQIT/LT-50:PVP K-30) in addition to the improvement in the in vitro shistosomidal activity at 1:4 (w/w) molar ratio (i.e., 20% drug loading) when compared to LQIT/LT-50 alone. The development of the LQIT/LT-50:PVP K-30 1:4 solid dispersion is encouraging for the future development of new pharmaceutical solid formulations, aiming the schistosomicidal treatment.

Drug Release from Surfactant-Containing Amorphous Solid Dispersions: Mechanism and Role of Surfactant in Release Enhancement

PURPOSE

To understand how surfactants affect drug release from ternary amorphous solid dispersions (ASDs), and to investigate different mechanisms of release enhancement.

METHODS

Ternary ASDs containing ritonavir (RTV), polyvinylpyrrolidone/vinyl acetate (PVPVA) and a surfactant (sodium dodecyl sulfate (SDS), Tween 80, Span 20 or Span 85) were prepared with rotary evaporation. Release profiles of ternary ASDs were measured with surface normalized dissolution. Phase separation morphologies of ASD compacts during hydration/dissolution were examined in real-time with a newly developed confocal fluorescence microscopy method. The water ingress rate of different formulations was measured with dynamic vapor sorption. Microscopy was employed to check for matrix crystallization during release studies.

RESULTS

All surfactants improved drug release at 30% DL, while only SDS and Tween 80 improved drug release at higher DLs, although SDS promoted matrix crystallization. The dissolution rate of neat polymer increased when SDS and Tween 80 were present. The water ingress rate also increased in the presence of all surfactants. Surfactant-incorporation affected both the kinetic and thermodynamics factors governing phase separation of RTV-PVPVA-water system, modifying the phase morphology during ASD dissolution. Importantly, SDS increased the miscibility of RTV-PVPVA-water system, whereas other surfactants mainly affected the phase separation kinetics/drug-rich barrier persistence.

CONCLUSION

Incorporation of surfactants enhanced drug release from RTV-PVPVA ASDs compared to the binary system. Increased drug-polymer-water miscibility and disruption of the drug-rich barrier at the gel-solvent interface via plasticization are highlighted as two key mechanisms underlying surfactant impacts based on direct visualization of the phase separation process upon hydration and release.

Spray-dried nanocrystal-loaded polymer microparticles for long-term release local therapies: an opportunity for poorly soluble drugs

Nano- and micro-technologies can salvage drugs with very low solubility that were doomed to pre-clinical and clinical failure. A unique design approach to develop drug nanocrystals (NCs) loaded in extended release polymeric microparticles (MPs) for local treatments is presented here through the case of a potential osteoarthritis (OA) drug candidate for intra-articular (IA) administration. Optimizing a low-shear wet milling process allowed the production of NCs that can be subsequently freeze-dried (FD) and redispersed in a hydrophobic polymer-organic solvent solution to form spray-dried MPs. Results demonstrated a successful development of a ready-to-upscale formulation containing PLGA MPs with high drug NC encapsulation rates that showed a continuous and controlled drug release profile over four months. The screenings and procedures described allowed for identifying and overcoming common difficulties and challenges raised along the drug reduction to nano-size and spray-drying process. Above all, the technical knowledge acquired is intended for formulation scientists aiming to improve the therapeutic perspectives of poorly soluble drugs.

Quality by design-based development and optimization of fourth-generation ternary solid dispersion of standardized Piper longum extract for melanoma therapy

The study aimed to enhance the solubility, dissolution, and oral bioavailability of standardized Piper longum fruits ethanolic extract (PLFEE) via fourth-generation ternary solid dispersion (SD) for melanoma therapy. With the use of solvent evaporation method, the standardized PLFEE was formulated into SD, optimized using Box-Wilson's central composite design (CCD), and evaluated for pharmaceutical performance and in vivo anticancer activity against melanoma (B16F10)-bearing C57BL/6 mice. The optimized SD showed good accelerated stability, high yield, drug content, and content uniformity for bioactive marker piperine (PIP). The X-ray diffraction (XRD), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and selected area electron diffraction (SAED) analysis revealed its amorphous nature. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and high-performance thin layer chromatography (HPTLC) revealed the compatibility of excipients with the PLFEE. The contact angle measurement and in vitro dissolution study revealed excellent wetting of SD and improved dissolution profile as compared to the plain PLFEE. The in vivo oral bioavailability of SD reflected a significant (p < 0.05) improvement in bioavailability (Frel = 188.765%) as compared to plain extract. The in vivo tumor regression study revealed the improved therapeutic activity of SD as compared to plain PLFEE. Further, the SD also improved the anticancer activity of dacarbazine (DTIC) as an adjuvant therapy. The overall result revealed the potential of developed SD for melanoma therapy either alone or as an adjuvant therapy with DTIC.

Engineering Inhalable Therapeutic Particles: Conventional and Emerging Approaches

Respirable particles are integral to effective inhalable therapeutic ingredient delivery, demanding precise engineering for optimal lung deposition and therapeutic efficacy. This review describes different physicochemical properties and their role in determining the aerodynamic performance and therapeutic efficacy of dry powder formulations. Furthermore, advances in top-down and bottom-up techniques in particle preparation, highlighting their roles in tailoring particle properties and optimizing therapeutic outcomes, are also presented. Practices adopted for particle engineering during the past 100 years indicate a significant transition in research and commercial interest in the strategies used, with several innovative concepts coming into play in the past decade. Accordingly, this article highlights futuristic particle engineering approaches such as electrospraying, inkjet printing, thin film freeze drying, and supercritical processes, including their prospects and associated challenges. With such technologies, it is possible to reshape inhaled therapeutic ingredient delivery, optimizing therapeutic benefits and improving the quality of life for patients with respiratory diseases and beyond.

Levofloxacin-Fatty Acid Systems: Dual Enhancement Through Deep Eutectic Formation and Solubilization for Pharmaceutical Potential and Antibacterial Activity

Fatty acids, including medium-chain saturated and polyunsaturated fatty acids, are known for their broad health benefits, including antimicrobial activity. Through their green properties, deep eutectic systems have been heralded as having the potential to be at the forefront of pharmaceutical applications. In this work, capric acid and geranic acid, two examples of medium-chain saturated and polyunsaturated fatty acids, were employed to enhance the pharmaceutical properties and the antibacterial activity of levofloxacin. To this end, levofloxacin formulations with either capric or geranic acid were prepared and characterized using appropriate techniques. Levofloxacin was utilized to create innovative deep eutectic systems in conjunction with capric acid at three different molar ratios: 1:9, 2:8 and 3:7. This was confirmed through a rigorous analysis involving nuclear magnetic resonance, infrared spectroscopy and differential scanning calorimetry. Furthermore, it is noteworthy that geranic acid demonstrated an impressive threefold improvement in levofloxacin's solubility compared to its solubility in aqueous solutions. The antibacterial activity of the novel combinations of levofloxacin with either fatty acid was evaluated using a checkerboard titration assay. Gratifyingly, both formulations exhibited synergistic effects against a panel of levofloxacin-sensitive and resistant Gram-negative bacteria. In conclusion, the observed superior antibacterial activity of levofloxacin illuminates the potential use of fatty acid-based formulations and deep eutectic systems as green and innovative strategies to combat the global antimicrobial resistance problem.

Modeling of the Aqueous Solubility of N-butyl-N-methyl-1-phenylpyrrolo[1,2-a] pyrazine-3-carboxamide: From Micronization to Creation of Amorphous-Crystalline Composites with a Polymer

N-butyl-N-methyl-1-phenylpyrrole[1,2-a] pyrazine-3-carboxamide (GML-3) is a potential candidate for combination drug therapy due to its anxiolytic and antidepressant activity. The anxiolytic activity of GML-3 is comparable to diazepam. The antidepressant activity of GML-3 is comparable to amitriptyline. GML-3 is an 18 kDa mitochondrial translocator protein (TSPO) ligand and is devoid of most of the side effects of diazepam, which makes the research on the creation of drugs based on it promising. However, its low water solubility and tendency to agglomerate prevented its release. This research aimed to study the effect of dry grinding, the rapid expansion of a supercritical solution (RESS), and the eutectic mixture (composite) of GML-3 with polyvinylpyrrolidone (PVP) on the particle size, dissolution rate, and lattice retention of GML-3. The use of supercritical CO2 in the RESS method was promising in terms of particle size reduction, resulting in a reduction in the particle size of GML-3 to 20-40 nm with a 430-fold increase in dissolution rate. However, in addition to particle size reduction after RESS, GML-3 began to show signs of a polymorphism phenomenon, which was also studied in this article. It was found that coarse grinding reduced particle size by a factor of 2 but did not significantly affect solubility or crystal structure. Co-milling with the polymer made it possible to level the effect of the appearance of a residual electrostatic charge on the particles, as in the case of grinding, and the increased solubility in the resulting mechanical mixtures of GML-3 with the polymer may also indicate the dissolving properties of polymers (an increase in 400-800 times). The best result in terms of GML-3 solubility was demonstrated by the resulting GML-3:PVP composite at a ratio of 1:4, which made it possible to achieve a solubility of about 80% active pharmaceutical ingredient (API) within an hour with an increase in the dissolution rate by 1600 times. Thus, the creation of composites is the most effective method for improving the solubility of GML-3, superior to micronization.

HPMCAS-Based Amorphous Solid Dispersions in Clinic: A Review on Manufacturing Techniques (Hot Melt Extrusion and Spray Drying), Marketed Products and Patents

Today, therapeutic candidates with low solubility have become increasingly common in pharmaceutical research pipelines. Several techniques such as hot melt extrusion, spray drying, supercritical fluid technology, electrospinning, KinetiSol, etc., have been devised to improve either or both the solubility and dissolution to enhance the bioavailability of these active substances belonging to BCS Class II and IV. The principle involved in all these preparation techniques is similar, where the crystal lattice of the drug is disrupted by either the application of heat or dissolving it in a solvent and the movement of the fine drug particles is arrested with the help of a polymer by either cooling or drying to remove the solvent. The dispersed drug particles in the polymer matrix have higher entropy and enthalpy and, thereby, higher free energy in comparison to the crystalline drug. Povidone, polymethaacrylate derivatives, hydroxypropyl methyl cellulose (HPMC) and hydroxypropyl methylcellulose acetate succinate derivatives are commonly used as polymers in the preparation of ASDs. Specifically, hydroxypropylmethylcellulose acetate succinate (HPMCAS)-based ASDs have become well established in commercially available products and are widely explored to improve the solubility of poorly soluble drugs. This article provides an analysis of two widely used manufacturing techniques for HPMCAS ASDs, namely, hot melt extrusion and spray drying. Additionally, details of HPMCAS-based ASD marketed products and patents have been discussed to emphasize the commercial aspect.

Solvent electrospinning amorphous solid dispersions with high itraconazole, celecoxib, mebendazole and fenofibrate drug loading and release potential

In this work, the feasibility of ultra-high drug loaded amorphous solid dispersions (ASDs) for the poorly soluble itraconazole, mebendazole and celecoxib via solvent electrospinning in combination with poly(2-ethyl-2-oxazoline) and fenofibrate in combination with polyvinylpyrrolidone is demonstrated. By lowering the polymer concentration in the electrospinning solution below its individual spinnable limit, ASDs with a drug content of up to 80 wt% are obtained. This is attributed to drug-polymer interactions not being limited by default to hydrogen bonds, as also Van der Waals interactions can result in high drug loadings. The theoretically predicted miscibility by the Flory-Huggins theory is corroborated by the experimental findings based on (modulated) differential scanning calorimetry and x-ray diffraction. Globally, the maximally obtained amorphous drug loadings are higher compared to the loadings found in literature. Additionally, non-sink dissolution tests demonstrate an increase in solubility of up to 50 times compared to their crystalline counterparts. Moreover, due to the lack of precipitation biocompatible PEtOx succeeds in stabilizing the dissolved drug and inhibiting its instant precipitation. The current work thus demonstrates the broader applicability of the electrospinning technique for the production of physically stable ASDs with ultra-high drug loadings, a result which has been validated for several Biopharmaceutics Classification System class II drugs.

Optimizing adjuvant inhaled chemotherapy: Synergistic enhancement in paclitaxel cytotoxicity by flubendazole nanocrystals in a cycle model approach

Lung cancer is the leading cause of cancer-related death. In addition to new innovative approaches, practical strategies that improve the efficacy of already available drugs are urgently needed. In this study, an inhalable dry powder formulation is used to repurpose flubendazole, a poorly soluble anthelmintic drug with potential against a variety of cancer lineages. Flubendazole nanocrystals were obtained through nanoprecipitation, and dry powder was produced by spray drying. Through fractional factorial design, the spray drying parameters were optimized and the impact of formulation on aerolization properties was clarified. The loading limitations were clarified through response surface methodology, and a 15% flubendazole loading was feasible through the addition of 20% L-leucine, leading to a flubendazole particle size of 388.6 nm, median mass aerodynamic diameter of 2.9 μm, 50.3% FPF, emitted dose of 83.2% and triple the initial solubility. Although the cytotoxicity of this formulation in A549 cells was limited, the formulation showed a synergistic effect when associated with paclitaxel, leading to a surprising 1000-fold reduction in the IC50. Compared to 3 cycles of paclitaxel alone, a 3-cycle model combined treatment increased the threshold of cytotoxicity by 25% for the same dose. Our study suggests, for the first time, that orally inhaled flubendazole nanocrystals show high potential as adjuvants to increase cytotoxic agents' potency and reduce adverse effects.

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.

In Silico Modeling Approaches Coupled with In Vitro Characterization in Predicting In Vivo Performance of Drug Delivery System Formulations

Optimization of the in vivo performance of dosage forms in humans is essential in developing not only conventional formulations but also drug delivery system (DDS) formulations. Although animal experiments are still useful for these formulations, in silico approaches have become increasingly important for DDS formulations with regard to species-specific differences in physiology that can affect the in vivo performance of dosage forms between animals and humans. Furthermore, it is also important to couple in vitro characterizations with in silico models to predict in vivo performance in humans precisely. In this review article, I summarized in vitro-in silico approaches to predicting the in vivo performance of oral DDS formulations (amorphous solid dispersions, lipid-based formulations, nanosized formulations, cyclodextrins-based formulations, sustained release products, enteric coat products, and orally disintegrating tablets) and parenteral DDS formulations (cyclodextrins-based formulations, liposomes, and inhaled formulations).

In vitro dissolution/permeation tools for amorphous solid dispersions bioavailability forecasting I: Experimental design for PermeaLoop™

Along with the increasing demand for candidate-enabling formulations comes the need for appropriate in vitro bioavailability forecasting. Dissolution/permeation (D/P) systems employing cell-free permeation barriers are increasingly gaining interest, due to their low cost and easy application as passive diffusion bio-predictive profiling in drug product development, as this accounts for nearly 75% of new chemical entities (NCEs) absorption mechanism. To this end, this study comprises theoretical considerations on the design and experimental work towards the establishment and optimization of a PermeaLoop™ based dissolution/permeation assay to simultaneously evaluate the drug release and permeation using Itraconazole (ITZ)-based amorphous solid dispersions (ASD) formulations, with different drug loads, based on a solvent-shift approach. Alternative method conditions were tested such as: donor medium, acceptor medium and permeation barrier were screened using both PermeaPad® and PermeaPlain® 96-well plates. A range of solubilizers, namely Sodium Dodecyl Sulfate, Vitamin E-TPGS and hydroxypropyl-β-cyclodextrin, were screened as possible solubilizing additives to the acceptor medium, while donor medium was varied between blank FaSSIF (phosphate buffer) and FaSSIF. The method optimization also included the ITZ dose selection, being the ITZ single dose (100 mg) considered the most adequate to be used in further experiments to allow the comparison with in vivo studies. In the end, a standardized approach that may be applied to predict the bioavailability of weakly basic poorly soluble drug-based formulations is described, contributing to strengthening the analytical portfolio of in vitro pre-clinical drug product development.

In vitro dissolution/permeation tools for amorphous solid dispersions bioavailability forecasting II: Comparison and mechanistic insights

Along with the increasing demand for complex formulations comes the need for appropriate in vitro methodologies capable of predicting their corresponding in vivo performance and the mechanisms controlling the drug release which can impact on in vivo drug absorption. In vitro dissolution-permeation (D/P) methodologies that can account for the effects of enabling formulations on the permeability of drugs are increasingly being used in performance ranking during early development stages. This work comprised the application of two different cell-free in vitro D/P setups: BioFLUX™ and PermeaLoop™ to evaluate the dissolution-permeation interplay upon drug release from itraconazole (ITZ)- HPMCAS amorphous solid dispersions (ASDs) of different drug loads. A solvent-shift approach was employed, from a simulated gastric environment to a simulated intestinal environment in the donor compartment. PermeaLoop™ was then combined with microdialysis sampling to separate the dissolved (free) drug from other species present in solution, like micelle-bound drug and drug-rich colloids, in real time. This setup was applied to clarify the mechanisms for drug release and permeation from these ASDs. In parallel, a pharmacokinetic study (dog model) was conducted to assess the drug absorption from these ASDs and to compare the in vivo results with the data obtained from each in vitro D/P setup, allowing to infer which would be the most adequate setup for ASD ranking. Even though both D/P systems resulted in the same qualitative ranking, BioFLUX™ overpredicted the difference between the in vivo AUC of two ASDs, whereas PermeaLoop™ permeation flux resulted in a good correlation with the AUC observed in pharmacokinetic studies (dog model) (R2 ≈ 0.98). Also, PermeaLoop™ combined with a microdialysis sampling probe clarified the mechanisms for drug release and permeation from these ASDs. It demonstrated that the free drug was the only driving force for permeation, while the drug-rich colloids kept permeation active for longer periods by acting as drug reservoirs and maintaining constant high levels of free drug in solution, which are then immediately able to permeate. Hence, the data obtained points BioFLUX™ and PermeaLoop™ applications to different momentums in the drug product development pipeline: while BioFLUX™, an automated standardized method, poses as a valuable tool for initial ASD ranking during the early development stages, PermeaLoop™ combined with microdialysis sampling allows to gain mechanistic understanding of the dissolution-permeation interplay, being crucial to fine tune and identify leading ASD candidates prior to in vivo testing.

Dissolution changes in drug-amino acid/biotin co-amorphous systems: Decreased/increased dissolution during storage without recrystallization

Co-amorphous systems have been proven to be a promising strategy to address the poor water solubility of poorly water-soluble drugs. Generally, the initial dissolution behaviors after co-amorphous system preparation and the potential recrystallization during storage are used to evaluate the performance of co-amorphous systems. However, this study reveals that decreased dissolution and unexpected increased dissolution were observed during storage though the co-amorphous systems maintained amorphous form. Three drugs (valsartan, tadalafil, mebendazole) and three co-formers (arginine, tryptophan, biotin) were used to prepare co-amorphous systems and the samples were stored for different times. After stored for 80 d, most of the co-amorphous systems maintained amorphous form, however, decreased and increased intrinsic dissolution rates (IDRs) were both observed in these non-recrystallized co-amorphous systems. The moisture changes of the systems during storage and the possible drug-co-former molecular interactions showed no effect on the dissolution changes, while phase separation might play a role in it. In conclusion, more attention should be paid to the dissolution changes of co-amorphous systems during storage. Focusing on the initial dissolution behaviors after sample preparation and the physical recrystallization during storage is not enough for the development of co-amorphous systems in future.

Impact of Poloxamer on Crystal Nucleation and Growth of Amorphous Clotrimazole

Surfactants have been widely used as effective additives to increase the solubility and dissolution rates of amorphous solid dispersions (ASDs). However, they may also generate adverse effects on the physical stability of ASDs. In this study, we systematically investigated the impacts of poloxamer, a frequently used surfactant, on the crystallization of amorphous clotrimazole (CMZ). The added poloxamer significantly decreased the glass transition temperature (Tg) of CMZ and accelerated the growth of Form 1 and Form 2 crystals. It was found that the poloxamer had an accelerating effect on Form 1 and Form 2 but showed a larger accelerating effect on Form 1, which resulted from a combined effect of increased mobility and local phase separation at the crystal-liquid interface. Additionally, the added poloxamer exhibited different effects on nucleation of the CMZ polymorphs, which was more complicated than crystal growth. The nucleation rate of Form 1 was significantly increased by the added poloxamer, and the effect increased with increasing P407 content. However, for Form 2, nucleation was slightly decreased or unchanged. The nucleation of Form 2 may have been influenced by the Form 1 crystallization, and Form 2 converted to Form 1 during nucleation. This study increases our understanding of poloxamer and its impacts on the melt crystallization of drugs.

Amorphous Solid Dispersion as Drug Delivery Vehicles in Cancer

Cancer treatment has improved over the past decades, but a major challenge lies in drug formulation, specifically for oral administration. Most anticancer drugs have poor water solubility which can affect their bioavailability. This causes suboptimal pharmacokinetic performance, resulting in limited efficacy and safety when administered orally. As a result, it is essential to develop a strategy to modify the solubility of anticancer drugs in oral formulations to improve their efficacy and safety. A promising approach that can be implemented is amorphous solid dispersion (ASD) which can enhance the aqueous solubility and bioavailability of poorly water-soluble drugs. The addition of a polymer can cause stability in the formulations and maintain a high supersaturation in bulk medium. Therefore, this study aimed to summarize and elucidate the mechanisms and impact of an amorphous solid dispersion system on cancer therapy. To gather relevant information, a comprehensive search was conducted using keywords such as "anticancer drug" and "amorphous solid dispersion" in the PubMed, Scopus, and Google Scholar databases. The review provides an overview and discussion of the issues related to the ASD system used to improve the bioavailability of anticancer drugs based on molecular pharmaceutics. A thorough understanding of anticancer drugs in this system at a molecular level is imperative for the rational design of the products.

Ternary Solid Dispersions: A Review of the Preparation, Characterization, Mechanism of Drug Release, and Physical Stability

The prevalence of active pharmaceutical ingredients (APIs) with low water solubility has experienced a significant increase in recent years. These APIs present challenges in formulation, particularly for oral dosage forms, despite their considerable therapeutic potential. Therefore, the improvement of solubility has become a major concern for pharmaceutical enterprises to increase the bioavailability of APIs. A promising formulation approach that can effectively improve the dissolution profile and the bioavailability of poorly water-soluble drugs is the utilization of amorphous systems. Numerous formulation methods have been developed to enhance poorly water-soluble drugs through amorphization systems, including co-amorphous formulations, amorphous solid dispersions (ASDs), and the use of mesoporous silica as a carrier. Furthermore, the successful enhancement of certain drugs with poor aqueous solubility through amorphization has led to their incorporation into various commercially available preparations, such as ASDs, where the crystalline structure of APIs is transformed into an amorphous state within a hydrophilic matrix. A novel approach, known as ternary solid dispersions (TSDs), has emerged to address the solubility and bioavailability challenges associated with amorphous drugs. Meanwhile, the introduction of a third component in the ASD and co-amorphous systems has demonstrated the potential to improve performance in terms of solubility, physical stability, and processability. This comprehensive review discusses the preparation and characterization of poorly water-soluble drugs in ternary solid dispersions and their mechanisms of drug release and physical stability.

Nucleation During Storage Impeded Supersaturation in the Dissolution Process of Amorphous Celecoxib

The aqueous solubility of active pharmaceutical ingredients (APIs) is one of the most critical factors in determining the absorption of orally administered drugs. Amorphization of API may offer better drug absorption than the crystalline state owing to enhanced solubility. However, if crystal nuclei are formed during storage, they may develop into crystals upon contact with water, thus limiting the dissolution advantage. In an earlier study, we found that the nuclei of amorphous celecoxib (CEL) could be formed at freezing temperatures (FT) without further crystal growth. Following this finding, we compared the dissolution performances of amorphous CEL annealed at room temperature (RT, 25 °C) or FT (-20 °C). We found that only the RT-annealed CEL could achieve a supersaturated state effectively during the dissolution process, which could be explained by the fast conversion of the FT-annealed amorphous CEL to a crystalline state owing to the presence of nuclei. Investigation of the residual solids revealed that supersaturation could be maintained for a while after the appearance of the crystals, which could be explained by heterogeneous nucleation and competition between the dissolution of amorphous parts and crystallization. In addition, a new crystalline form of CEL was observed during dissolution.

Enhancing bioavailability of natural extracts for nutritional applications through dry powder inhalers (DPI) spray drying: technological advancements and future directions

Natural ingredients have many applications in modern medicine and pharmaceutical projects. However, they often have low solubility, poor chemical stability, and low bioavailability in vivo. Spray drying technology can overcome these challenges by enhancing the properties of natural ingredients. Moreover, drug delivery systems can be flexibly designed to optimize the performance of natural ingredients. Among the various drug delivery systems, dry powder inhalation (DPI) has attracted much attention in pharmaceutical research. Therefore, this review will focus on the spray drying of natural ingredients for DPI and discuss their synthesis and application.

Intravenous nanocrystals: fabrication, solidification, in vivo fate, and applications for cancer therapy

INTRODUCTION

Intravenous nanocrystals (INCs) have shown intrinsic advantages in antitumor applications, particularly their properties of high drug loading, low toxicity, and controllable size. Therefore, it has a very bright application prospect as a drug delivery system.

AREAS COVERED

The ideal formulation design principles, fabrication, solidification, in vivo fate of INCs, the applications in drug delivery system (DDS) and the novel applications are covered in this review.

EXPERT OPINION

It is vital to select a suitable formulation and fabrication method to produce a stable and sterile INCs. Besides, the type of stabilizers and physical characteristics can also influence the in vivo fate of INCs, which is worthy of further studying. Based on wide researches about applications of INCs in cancer, biomimetic INCs are concerned increasingly for its favorable compatibility. The output of these studies suggested that INCs-based drug delivery could be a novel strategy for addressing the delivery of the drug that faces solubility, bioavailability, and toxicity problems.

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

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

Nanocrystals in cosmetics and cosmeceuticals by topical delivery

The main issues with local delivery of cosmetics are their high sensitivity and limited drug loading of active pharmaceutical ingredient. Nanocrystal technology offers consumers cutting-edge and effective products and exhibits enormous development potential in the beauty business as a new delivery method to address the issue of low solubility and low permeability of sensitive chemicals. In this review, we described the processes for making NCs, along with the impacts of loading and the uses of different carriers. Among them, nanocrystalline loaded gel and emulsion are widely used and may further improve the stability of the system. Then, we introduced the beauty efficacy of drug NCs from five aspects: anti-inflammation and acne, anti-bacterial, lightening and freckle removal, anti-aging as well as UV protection. Following that, we presented the current scenario about stability and safety. Finally, the challenges and vacancy were discussed along with the potential uses of NCs in the cosmetics industry. This review serves as a resource for the advancement of nanocrystal technology in the cosmetics sector.

Pre-Processing a Polymer Blend into a Polymer Alloy by KinetiSol Enables Increased Ivacaftor Amorphous Solid Dispersion Drug Loading and Dissolution

This study compares the effects of pre-processing multiple polymers together to form a single-phase polymer alloy prior to amorphous solid dispersion formulation. KinetiSol compounding was used to pre-process a 1:1 (w/w) ratio of hypromellose acetate succinate and povidone to form a single-phase polymer alloy with unique properties. Ivacaftor amorphous solid dispersions comprising either a polymer, an unprocessed polymer blend, or the polymer alloy were processed by KinetiSol and examined for amorphicity, dissolution performance, physical stability, and molecular interactions. A polymer alloy ivacaftor solid dispersion with a drug loading of 50% w/w was feasible versus 40% for the other compositions. Dissolution in fasted simulated intestinal fluid revealed that the 40% ivacaftor polymer alloy solid dispersion reached a concentration of 595 µg/mL after 6 h, 33% greater than the equivalent polymer blend dispersion. Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance revealed changes in the ability of the povidone contained in the polymer alloy to hydrogen bond with the ivacaftor phenolic moiety, explaining the differences in the dissolution performance. This work demonstrates that the creation of polymer alloys from polymer blends is a promising technique that provides the ability to tailor properties of a polymer alloy to maximize the drug loading, dissolution performance, and stability of an ASD.

Predicting Glass-Forming Ability of Pharmaceutical Compounds by Using Machine Learning Technologies

Low aqueous solubility is a common and serious challenge for most drug substances not only in development but also in the market, and it may cause low absorption and bioavailability as a result. Amorphization is an intermolecular modification strategy to address the issue by breaking the crystal lattice and enhancing the energy state. However, due to the physicochemical properties of the amorphous state, drugs are thermodynamically unstable and tend to recrystallize over time. Glass-forming ability (GFA) is an experimental method to evaluate the forming and stability of glass formed by crystallization tendency. Machine learning (ML) is an emerging technique widely applied in pharmaceutical sciences. In this study, we successfully developed multiple ML models (i.e., random forest (RF), XGBoost, and support vector machine (SVM)) to predict GFA from 171 drug molecules. Two different molecular representation methods (i.e., 2D descriptor and Extended-connectivity fingerprints (ECFP)) were implemented to process the drug molecules. Among all ML algorithms, 2D-RF performed best with the highest accuracy, AUC, and F1 of 0.857, 0.850, and 0.828, respectively, in the testing set. In addition, we conducted a feature importance analysis, and the results mostly agreed with the literature, which demonstrated the interpretability of the model. Most importantly, our study showed great potential for developing amorphous drugs by in silico screening of stable glass formers.

Application of biorelevant in vitro assays for the assessment and optimization of ASD-based formulations for pediatric patients

Amorphous solid dispersions (ASD) have been a successful formulation strategy to overcome the poor aqueous solubility of many novel drugs, but the development of pediatric formulations presents a special challenge due to variable gastrointestinal conditions in children. It was the aim of this work to design and apply a staged biopharmaceutical test protocol for the in vitro assessment of ASD-based pediatric formulations. Ritonavir was used as a model drug with poor aqueous solubility. Based on the commercial ASD powder formulation, a mini-tablet and a conventional tablet formulation were prepared. Drug release from the three formulations was studied in different biorelevant in vitro assays (i.e. MicroDiss, two-stage, transfer model, tiny-TIM) to consider different aspects of human GI physiology. Data from the two-stage and transfer model tests indicated that by controlled disintegration and dissolution excessive primary precipitation can be prevented. However, this advantage of the mini-tablet and tablet formulation did not translate into better performance in tiny-TIM. Here, the in vitro bioaccessibility was comparable for all three formulations. In the future, the staged biopharmaceutical action plan established herein will support the development of ASD-based pediatric formulations by improving the mechanistic understanding so that formulations are developed for which drug release is robust against variable physiological conditions.

Skin permeation of curcumin nanocrystals: Effect of particle size, delivery vehicles, and permeation enhancer

Nanocrystals are characterized by high drug loading, low carrier toxicity, and great structural stability. Therefore, they are a promising and versatile strategy for enhancing the local delivery of insoluble drugs. They achieve this by improving skin adhesion, concentration gradients, and hair follicle accumulation, as well as generating corona diffusion (which forms through the overlap of dissolved drug molecules around a nanocrystal). The development of suitable formulations for enhancing the passive diffusion and/or follicular targeting of nanocrystals is of great importance to clinical practice. We sought to elucidate the influence of particle size, a penetration enhancer, and delivery vehicles on the follicular accumulation and passive dermal permeation of nanocrystals. For this purpose, curcumin nanocrystals (particle size: 60, 120, and 480 nm) were incorporated into xanthan gum gels (delivery vehicles) with propylene glycol (penetration enhancer). This evaluation was performed in a porcine skin model. The results showed that xanthan gum reduced the follicular penetration and passive skin accumulation of curcumin nanocrystals. The propylene glycol enhanced the skin penetration and retention of curcumin nanocrystals in vitro for 24 h. The curcumin nanocrystals of smaller particle size (i.e., 60 and 120 nm) displayed higher passive skin penetration versus those with larger particle size (i.e., 480 nm); however, the latter type showed deeper follicular accumulation. In conclusion, the delivery vehicles, penetration enhancer, and particle sizes examined in this study affect the dermal penetration and accumulation of curcumin nanocrystals. Hence, their effects should be adequately considered when designing formulations of such nanocrystals.

Enhanced dissolution rate of nimodipine through β-lactoglobulin based formulation

Amorphous solid dispersions (ASD) have been considered as one of the most effective strategies to increase solubility and dissolution rate of poorly water-soluble drugs. Carriers, in which the poorly water-soluble drug is dispersed, contribute a large extent to the solid-state properties, stabilities and dissolution performance of ASDs. This study investigated the solid-state properties, physical stability, and in vitro dissolution behaviour of nimodipine ASDs formulated with a traditional polymeric carrier, i.e., polyvinylpyrrolidone (PVP) and a novel carrier, i.e., β-lactoglobulin (BLG). The ASDs with both carriers were prepared using ball milling as preparative technique at 10 %, 17.5 %, 25 %, 30 % and 40 % drug loadings (DLs). All the formulations were found to be amorphous upon milling for 60 min based on X-ray powder diffraction measurements, however, the ASDs were found to be homogeneous unequivocally only at DLs below 25 %. After open storage at accelerated conditions (40 °C/75 % relative humidity), only the ASDs formulated with BLG at 10 % and 17.5 % DLs maintained the amorphous form. The dissolution study revealed that all the freshly prepared ASDs formulated with PVP and the ASDs formulated with BLG at or above 25 % DLs, showed a low drug release (<30 µg/mL in simulated gastric fluid, < 70 µg/mL in simulated intestinal fluid). Whilst the ASD formulated with BLG at 10 % DL exhibited a high drug release with a maximum concentration (C_max) of 251 µg/mL in simulated gastric fluid and 231 µg/mL in simulated intestinal fluid. Surprisingly, the ASD formulated with BLG at 17.5 % DL demonstrated an even higher drug release (C_max, 643 µg/mL in simulated gastric fluid, 332 µg/mL in simulated intestinal fluid), compared to the ASD of 10 % DL. These findings underline the importance of rationally investigating both carrier types and DL in the design of ASDs, in order to obtain a stable ASD with the desired enhanced dissolution rate of poorly water-soluble drugs.

Improving solubility of poorly water-soluble drugs by protein-based strategy: A review

Poorly water-soluble drugs are frequently encountered and present a most challengeable difficulty in pharmaceutical development. Poor solubility of drugs can lead to suboptimal bioavailability and therapeutic efficiency. Increasing efforts have been contributed to improve the solubility of poorly water-soluble drugs for better pharmacokinetics and pharmacodynamics. Among various solubility enhancement technologies, protein-based strategy to address poorly water-soluble drugs issues has special interests for natural advantages including versatile interactions between proteins and hydrophobic drugs, biocompatibility, biodegradation, and metabolization of proteins. The protein-drug formulations could be formed by covalent conjugations or noncovalent interactions to facilitate solubility of poorly water-soluble drugs. This review is to summarize the advances using proteins including plant proteins, mammalian proteins, and recombinant proteins, to enhance water solubility of poorly water-soluble drugs.

Release Enhancement by Plasticizer Inclusion for Amorphous Solid Dispersions Containing High Tg Drugs

PURPOSE

Plasticizers are commonly used in the preparation of amorphous solid dispersions (ASDs) with the main goal of aiding processability; however, to the best of our knowledge, the impact of plasticizers on drug release has not been explored. The goal of this study was to evaluate diverse plasticizers, including glycerol and citrate derivatives, as additives to increase the drug loading where good drug release could be achieved from copovidone (PVPVA)-based dispersions, focusing on high glass transition (T_g) drugs, atazanavir (ATZ) and ledipasvir (LED).

METHODS

ASDs were prepared using the high T_g compounds, atazanavir (ATZ) and ledipasvir (LED), as model drugs. Release was evaluated using surface normalized dissolution testing. Differential scanning calorimetry was used to measure glass transition temperature and water vapor sorption was performed on select samples.

RESULTS

The presence of a plasticizer at 5% w/w for ATZ and 10% w/w for LED ASDs, led to improved drug release. For ATZ ASDs, in the absence of plasticizer, release was very poor at drug loadings of 10% w/w and above. Good release was obtained for plasticized ASDs up to a drug loading of 25%. The corresponding improvement for LED was from 5 to 20% DL. Interestingly, for a low T_g compound, ritonavir, relatively smaller improvements in release as a function of drug loading were achieved through plasticizer incorporation.

CONCLUSIONS

The use of plasticizers represents a potential new strategy to increase drug loading in ASDs for high T_g compounds with a low tendency to crystallize and may help improve a major limitation of ASD formulations, namely the high excipient burden.

Effect of Different Seed Crystals on the Supersaturation State of Ritonavir Tablets Prepared by Hot-Melt Extrusion

Hot-melt extrusion (HME) is a technology increasingly common for the commercial production of pharmaceutical amorphous solid dispersions (ASDs), especially for poorly water-soluble active pharmaceutical ingredients (APIs). However, recrystallization of the APIs during dissolution must be prevented to maintain the supersaturation state enabled by ASD. Unfortunately, the amorphous formulation may be contaminated by seed crystals during the HME manufacturing process, which could lead to undesirable crystal growth during the dissolution process. In this study, the dissolution behavior of ritonavir ASD tablets prepared using both Form I and Form II polymorphs was examined, and the effects of different seed crystals on crystal growth rates were investigated. The aim was to understand how the presence of seed crystals can impact the dissolution of ritonavir, and to determine the optimal polymorph and seeding conditions for the production of ASDs. The results showed that both Form I and Form II ritonavir tablets had similar dissolution profiles, which were also similar to the reference listed drug (RLD). However, it was observed that the presence of seed crystals, particularly the metastable Form I seed, led to more precipitation compared to the stable Form II seed in all formulations. The Form I crystals that precipitated from the supersaturated solution were easily dispersed in the solution and could serve as seeds to facilitate crystal growth. On the other hand, Form II crystals tended to grow more slowly and presented as aggregates. The addition of both Form I and Form II seeds could affect their precipitation behaviors, and the amount and form of the seeds had significant effects on the precipitation process of the RLD tablets, as are the tablets prepared with different polymorphs. In conclusion, the study highlights the importance of minimizing the contamination risk of seed crystals during the manufacturing process and selecting the appropriate polymorph for the production of ASDs.

Amorphous Solid Dispersions Layered onto Pellets—An Alternative to Spray Drying?

Spray drying is one of the most frequently used solvent-based processes for manufacturing amorphous solid dispersions (ASDs). However, the resulting fine powders usually require further downstream processing when intended for solid oral dosage forms. In this study, we compare properties and performance of spray-dried ASDs with ASDs coated onto neutral starter pellets in mini-scale. We successfully prepared binary ASDs with a drug load of 20% Ketoconazole (KCZ) or Loratadine (LRD) as weakly basic model drugs and hydroxypropyl-methyl-cellulose acetate succinate or methacrylic acid ethacrylate copolymer as pH-dependent soluble polymers. All KCZ/ and LRD/polymer mixtures formed single-phased ASDs, as indicated by differential scanning calorimetry, X-ray powder diffraction and infrared spectroscopy. All ASDs showed physical stability for 6 months at 25 °C/65% rH and 40 °C/0% rH. Normalized to their initial surface area available to the dissolution medium, all ASDs showed a linear relationship of surface area and solubility enhancement, both in terms of supersaturation of solubility and initial dissolution rate, regardless of the manufacturing process. With similar performance and stability, processing of ASD pellets showed the advantages of a superior yield (>98%), ready to use for subsequent processing into multiple unit pellet systems. Therefore, ASD-layered pellets are an attractive alternative in ASD-formulation, especially in early formulation development at limited availability of drug substance.

Albumin-Based Silibinin Nanocrystals Targeting Activated Hepatic Stellate Cells for Liver Fibrosis Therapy

Activated hepatic stellate cells (aHSCs) are critical during the development and progression of liver fibrosis. Once liver fibrosis occurs, aHSCs highly express secreted protein, acidic and rich in cysteine (SPARC), a typical albumin-binding protein. We designed a nano platform, silibinin albumin nanocrystals (SLB-HSA NCs), to target aHSCs for liver fibrosis therapy. The prepared SLB-HSA NCs showed uniform particle size distribution of approximately 60 nm with PDI < 0.15 and high loading efficiency up to 49.4%. Albumin coated on the surface of nanocrystals was demonstrated to increase cellular uptake by aHSCs through SPARC-mediated endocytosis. In addition, SLB-HSA NCs significantly improved the bioavailability compared with free SLB in pharmacokinetic study. Following tail-vein injection, SLB-HSA NCs were massively accumulated in the fibrotic liver and exhibited enhanced antifibrotic effects in hepatic fibrosis mice. Overall, our findings prove the great potential of SLB-HSA NCs in the targeted treatment of liver fibrosis.