Effect of plasticizers on manufacturing ritonavir/copovidone solid dispersions via hot-melt extrusion: Preformulation, physicochemical characterization, and pharmacokinetics in rats

Exploring the impact of material selection on the efficacy of hot-melt extrusion

Hot-melt extrusion (HME) has emerged as a versatile and efficient technique in pharmaceutical formulation development, particularly for enhancing the solubility and bioavailability of poorly water-soluble drugs. This review delves into the fundamental principles of HME, exploring its application in drug delivery systems. A comprehensive analysis of polymers utilized in HME, such as hydroxypropyl methylcellulose, ethyl cellulose, hydroxypropyl cellulose, and polyvinylpyrrolidone, is presented, highlighting their roles in achieving controlled drug release and improved stability. The incorporation of plasticizers, such as triacetin, poly(propylene glycol), glycerol, and sorbitol, is critical in reducing the glass transition temperature (Tg) of polymer blends, thereby enhancing the processability of HME formulations. A comparison of Tg values for various polymer-plasticizer combinations is discussed using different predictive models. For researchers and industry professionals looking to optimize drug formulation strategies, this article offers valuable insights into the mechanisms through which HME enhances drug solubility and bioavailability two critical factors in oral drug delivery. Furthermore, by reviewing recent patents and marketed formulations, the article serves as a comprehensive resource for understanding both the technical advancements and commercial applications of HME. Readers will gain a deep understanding of the role of polymers and additives in HME, alongside future perspectives on how emerging materials and techniques could further revolutionize pharmaceutical development. This review is essential for those aiming to stay at the forefront of pharmaceutical extrusion technologies and their potential to improve therapeutic outcomes. The review concludes that meticulous material selection is vital for advancing pharmaceutical manufacturing processes and ensuring optimal outcomes in HME applications, thereby enhancing the overall efficacy of drug delivery systems.

Melt-extruded formulations of fenofibrate with various grades of hydrogenated phospholipid exhibit promising in-vitro biopharmaceutical behavior

In the current study, it was demonstrated that three commercially available grades of hydrogenated phospholipids (HPL) differing in their content of phosphatidylcholine may be used as components for hot melt-extruded binary (HPL as sole excipient) or ternary (in combination with copovidone) solid dispersions of fenofibrate (FEN) at mass fractions between 0.5 and 20% (ternary) or 80% (binary). X-ray powder diffraction indicated complete conversion of crystalline fenofibrate into the amorphous state by hot melt extrusion for all ternary blends. In contrast, both the binary blends (HPL- and copovidone-based) contained minor remaining crystallites. Irrespectively, all solid dispersions induced during dissolution studies a supersaturated state of FEN, where the ternary ASDs showed enhanced and more complete release of FEN as compared to the binary blends and, even more pronounced, in comparison to the marketed micronized and nano-milled formulations. In terms of the cumulated amount permeated, there were marginal differences between the various formulations when combined dissolution/permeation was done using FeSSIF as donor medium; with FaSSIF as donor medium, the binary HPL-ASD containing the grade with the highest phosphatidylcholine fraction performed best in terms of permeation, even significantly better than the marketed nano-crystal formulation. Otherwise, no significant differences were seen between the various grades of HPL when FEN dissolution and permeation were analyzed for ternary solid dispersions. In conclusion, the in-vitro biopharmaceutical behaviour of hydrogenated phospholipid-containing blends manufactured by hot melt extrusion appears promising. They can be a viable formulation option for poorly water-soluble and lipophilic drug compounds like FEN.

Investigation of the Influence of Copovidone Properties and Hot-Melt Extrusion Process on Level of Impurities, In Vitro Release, and Stability of an Amorphous Solid Dispersion Product

Hot-melt extrusion (HME) is a widely used method for creating amorphous solid dispersions (ASDs) of poorly soluble drug substances, where the drug is molecularly dispersed in a solid polymer matrix. This study examines the impact of three different copovidone excipients, their reactive impurity levels, HME barrel temperature, and the distribution of colloidal silicon dioxide (SiO2) on impurity levels, stability, and drug release of ASDs and their tablets. Initial peroxide levels were higher in Kollidon VA 64 (KVA64) and Plasdone S630 (PS630) compared to Plasdone S630 Ultra (PS630U), leading to greater oxidative degradation of the drug in fresh ASD tablets. However, stability testing (50 °C, closed container, 50 °C/30% RH, open conditions) showed lower oxidative degradation impurities in ASD tablets prepared at higher barrel temperatures, likely due to greater peroxide degradation. Plasdone S630 is suitable for ASDs with drugs prone to oxidative degradation, while standard purity grades may benefit drugs susceptible to free radical degradation, as they generate fewer free radicals post-HME. ASD tablets exhibited greater physical stability than milled extrudate samples, likely due to reduced exposure to stability conditions within the tablet matrix. Including SiO2 in the extrudate composition resulted in greater physical stability of the ASD system in the tablet; however, it negatively affected chemical stability, promoting greater oxidative degradation and hydroxylation of the drug substance. No impact of the distribution of SiO2 on drug release was observed. The study also confirmed the congruent release of copovidone, the drug substance, and Tween 80 using flow NMR coupled with in-line UV/vis. This research highlights the critical roles of peroxide levels and SiO2 in influencing the dissolution and physical and chemical stability of ASDs. The findings provide valuable insights for developing stable and effective pharmaceutical formulations, emphasizing the importance of controlling reactive impurities and excipient characteristics in ASD products prepared by using HME.

Physicochemical interaction of rifampicin and ritonavir-lopinavir solid dispersion: an in-vitro and ex-vivo investigation

OBJECTIVE

To investigate the in-situ physicochemical interaction of Rifampicin and Ritonavir - Lopinavir Solid dispersion administered for the treatment of comorbid conditions i.e. Tuberculosis and HIV/AIDS.

METHODS

pH-shift dissolution of Rifampicin (RIF) in presence of Ritonavir-Lopinavir solid dispersion (RL-SD) was carried out in USP phosphate buffer 6.8 and FaSSIF. Equilibrium and amorphous solubility were determined for the drugs. Pure drugs, their physical mixtures, and pH-shifted co-precipitated samples were characterized using DSC, PXRD, and FTIR. Fluorescence spectroscopy was used to investigate drug-rich and drug-lean phases. In-vitro and ex-vivo flux studies were also carried out.

RESULTS

The results showed significant differences in the solubility and dissolution profiles of RTV and LOP in the presence of RIF, while RIF profile remained unchanged. Amorphicity, intermolecular interaction and aggregate formation in pH-shifted samples were revealed in DSC, XRD and FTIR analysis. Fluorescence spectroscopy confirmed the formation of drug-rich phase upon pH-shift. In-vitro and ex-vivo flux studies revealed significant reduction in the flux of all the drugs when studied in presence of second drug.

CONCLUSION

RIF, RTV and LOP in presence of each other on pH-shift, results in co-precipitation in the amorphous form (miscible) which leads to reduction in the highest attainable degree of supersaturation. This reduction corresponds to the mole fraction of the RIF, RTV and LOP within the studied system. These findings suggest that the concomitant administration of these drugs may lead to physicochemical interactions and possible ineffective therapy.

Hot-Melt Extrusion: from Theory to Application in Pharmaceutical Formulation-Where Are We Now?

Hot-melt extrusion (HME) is a globally recognized, robust, effective technology that enhances the bioavailability of poorly soluble active pharmaceutical ingredients and offers an efficient continuous manufacturing process. The twin-screw extruder (TSE) offers an extremely resourceful customizable mixer that is used for continuous compounding and granulation by using different combinations of conveying elements, kneading elements (forward and reverse configuration), and distributive mixing elements. TSE is thus efficiently utilized for dry, wet, or melt granulation not only to manufacture dosage forms such as tablets, capsules, or granule-filled sachets, but also for designing novel formulations such as dry powder inhalers, drying units for granules, nanoextrusion, 3D printing, complexation, and amorphous solid dispersions. Over the past decades, combined academic and pharmaceutical industry collaborations have driven novel innovations for HME technology, which has resulted in a substantial increase in published articles and patents. This article summarizes the challenges and models for executing HME scale-up. Additionally, it covers the benefits of continuous manufacturing, process analytical technology (PAT) considerations, and regulatory requirements. In summary, this well-designed review builds upon our earlier publication, probing deeper into the potential of twin-screw extruders (TSE) for various new applications.

Elucidation of Molecular Interactions Between Drug-Polymer in Amorphous Solid Dispersion by a Computational Approach Using Molecular Dynamics Simulations

Introduction

Amorphous drug dispersion is frequently used to enhance the solubility and dissolution of poorly water-soluble drugs, thereby improving their oral bioavailability. The dispersion of these drugs into polymer matrix can inhibit their recrystallization. The inter-molecular interactions between drug and polymer plays a role in the improvement of the dissolution rate, solubility, and physical stability of drug.

Aim

This study aims to investigate the formation and interactions of ritonavir (RTV)/poloxamer (PLX) amorphous formulation using a computational approach via molecular dynamics (MD) simulations, which mimicked solvent evaporation and melt-quenching method.

Methods

TheRoot Mean Square Deviation (RMSD) value, Root Mean Square Fluctuation (RMSF), Radial Distribution Function (RDF), Radius of Gyration (Rg), Solvent Accessible Surface Area (SASA), and hydrogen bond interactions were analyzed to determine interaction mechanisms between RTV and PLX in amorphous solid dispersion.

Results

The pi-alkyl bonds between RTV and PLX were formed after simulations of solvent evaporation, while the hydrogen bond interactions of RTV-PLX was observed during melt method simulations. These results indicate the successful formulation of amorphous solid dispersion (ASD) from RTV and PLX. The RMSD values obtained from the solvent evaporation, melt-cooling-A, melt-cooling-B, and melt-cooling-C methods were 3.33 Å, 1.97 Å, 1.30 Å, and 1.29 Å, respectively, while the average RMSF values were 2.65 Å, 1.04 Å, 1.05 Å, and 1.07 Å, respectively. This indicates that the suppression of translational motion of RTV from the melt method can be stronger than solvent evaporation caused by the intermolecular interactions of RTV-PLX.

Conclusion

MD simulations helped in understanding the formation and interaction mechanisms of ASD formulations that were difficult to detect by experimental approaches.

Impact of hypromellose acetate succinate and Soluplus® on the performance of β-carotene solid dispersions with the aid of sorbitan monolaurate: In vitro-in vivo comparative assessment

Solid dispersions (SDs) possess the potential to enhance the bioavailability of insoluble active pharmaceutical ingredients (APIs) by effectively converting them into amorphous state. However, SDs have a tendency to recrystallize unless appropriate excipients are employed. The objective of this study was to evaluate the ability of hypromellose acetate succinate HF (HPMCAS-HF) and Soluplus® to inhibit the recrystallization of β-carotene and improve its in vivo bioavailability through the fabrication of ternary β-carotene solid dispersions (SDs) with the aid of specific surfactant. Due to rapid micellization, the dissolution profiles of β-carotene SDs based on HPMCAS-HF/Span 20 (5:5, w/w) or Soluplus®/Span 20 (6:4, w/w) combinations exhibited significant improvement, which were almost 7-10 times higher than β-carotene bulk powder. DSC and PXRD analysis indicated a notable reduction in the crystallinity degree of β-carotene within the SDs. The stability study demonstrated a half-life of β-carotene in the SDs exceeding 30 days. Additionally, the in vivo pharmacokinetics analysis confirmed that the cellulose derivatives/surfactant combinations significantly enhanced the bioavailability of β-carotene by 1.37-fold and 2.3-fold, respectively. Notably, the HPMCAS-HF/Span 20 combination exhibited superior performance. Consequently, the HPMCAS-HF/Span 20 combination held potential for the advancement of an effective drug delivery system for β-carotene.

Quality by design (QbD) approach to develop fast-dissolving tablets using melt-dispersion paired with surface-adsorption method: formulation and pharmacokinetics of flurbiprofen melt-dispersion granules

Developing amorphous solid dispersions with good flow properties is always challenging for formulation scientists to convert into tablets. Hence, the present study investigates the impact of the combination of melt-dispersion and surface-adsorption methods to prepare melt-dispersion granules with enhanced dissolution rate and flow properties. This study covers the formulation and pharmacokinetic study of fast-dissolving flurbiprofen tablets using PEG 6000 (hydrophilic carrier) and lactose (adsorbent). Response surface methodology (RSM) using the central composite design (CCD) was used to optimize independent variables like carrier concentrations and adsorbent concentrations, and their interactions with the dependent variables (responses), including solubility, angle of repose, Carr's index, and cumulative % drug release, were investigated. The optimized formulation was selected based on the numerical optimization method and further investigated for FTIR spectroscopy, differential scanning calorimetry, and X-ray diffractometry. Then, the optimized formulation was compressed into tablets and evaluated for both in vitro dissolution and in vivo pharmacokinetics parameters. In vitro dissolution studies revealed that the prepared fast-dissolving tablets released the drug entirely within 15 min (Q15 of F4 tablets: 99.34 ± 1.24%), whereas conventional tablets took around 60 min for complete dissolution. Pharmacokinetic studies in rats revealed that fast-dissolving tablets showed 1.38-fold higher peak-plasma concentration (Cmax) and 1.39-fold higher bioavailability than conventional tablets. Overall, this study revealed the successful fabrication of fast-dissolving tablets via melt-dispersion paired with the surface-adsorption method to enhance the flow properties and the dissolution rate.

Hydrogenated phospholipid, a promising excipient in amorphous solid dispersions of fenofibrate for oral delivery: Preparation and in-vitro biopharmaceutical characterization

Amorphous solid dispersions (ASD) represent a viable formulation strategy to improve dissolution and bioavailability of poorly soluble drugs. Our study aimed to evaluate the feasibility and potential role of hydrogenated phospholipid (HPL) as a matrix material and solubilizing additive for binary (alone) or ternary (in combination with polymers) solid dispersions, using fenofibrate (FEN) as the model drug. FEN, incorporated within ASDs by melting or freeze-drying (up to 20% m/m), stayed amorphous during short-term stability studies. The solubility enhancing potential of HPL depended on the dissolution medium. In terms of enhancing in vitro permeation, solid dispersions with HPL were found equally or slightly more potent as compared to the polymer-based ASD. For studied ASD, in vitro permeation was found substantially enhanced as compared to a suspension of crystalline FEN and at least equal compared to marketed formulations under comparable conditions (literature data). Additionally, while the permeation of neat FEN and FEN in binary solid dispersions was affected by the dissolution medium (i.e., the "prandial state"), for ternary solid dispersions the permeation was independent of the "prandial state" (FaSSIF = FeSSIF). This suggests that ternary solid dispersions containing both polymer and HPL may represent a viable formulation strategy to mitigate fenofibrate's food effect.

Development of Lipid Polymer Hybrid Drug Delivery Systems Prepared by Hot-Melt Extrusion

This study sought to develop polymer-lipid hybrid solid dispersions containing the poorly soluble drug lopinavir (LPV) by hot-melt extrusion (HME). Hence, the lipid and polymeric adjuvants were selected based on miscibility and compatibility studies. Film casting was used to assess the miscibility, whereas thermal, spectroscopic, and chromatographic analyses were employed to evaluate drug-excipient compatibility. Extrudates were obtained and characterized by physicochemical tests, including in vitro LPV dissolution. Preformulation studies led to select the most appropriate materials, i.e., the polymers PVPVA and Soluplus®, the plasticizers polyethylene glycol 400 and Kolliphor® HS15, phosphatidylcholine, and sodium taurodeoxycholate. HME processing did not result in LPV degradation and significantly increased entrapment efficiency (93.8% ± 2.8 for Soluplus® extrudate against 19.8% ± 0.5 of the respective physical mixture). LPV dissolution was also increased from the extrudates compared to the corresponding physical mixtures (p < 0.05). The dissolution improvement was considerably greater for the Soluplus®-based formulation (24.3 and 2.8-fold higher than pure LPV and PVPVA-based extrudate after 120 min, respectively), which can be attributed to the more pronounced effects of HME processing on the average size and LPV solid-state properties in the Soluplus® extrudates. Transmission electron microscopy and chemical microanalysis suggested that the polymer-lipid interactions in Soluplus®-based formulation depended on thermal processing.

Progress on COVID-19 Chemotherapeutics Discovery and Novel Technology

COVID-19 is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel highly contagious and pathogenic coronavirus that emerged in late 2019. SARS-CoV-2 spreads primarily through virus-containing droplets and small particles of air pollution, which greatly increases the risk of inhaling these virus particles when people are in close proximity. COVID-19 is spreading across the world, and the COVID-19 pandemic poses a threat to human health and public safety. To date, there are no specific vaccines or effective drugs against SARS-CoV-2. In this review, we focus on the enzyme targets of the virus and host that may be critical for the discovery of chemical compounds and natural products as antiviral drugs, and describe the development of potential antiviral drugs in the preclinical and clinical stages. At the same time, we summarize novel emerging technologies applied to the research on new drug development and the pathological mechanisms of COVID-19.

Optimization of Meloxicam Solid Dispersion Formulations for Dissolution Enhancement and Storage Stability Using 33 Full Factorial Design Based on Response Surface Methodology

This study aimed to formulate and optimize solid-dispersion of meloxicam (MX) employing response-surface-methodology (RSM). RSM allowed identification of the main effects and interactions between studied factors on MX dissolution and acceleration of the optimization process. 3³ full factorial design with 27 different formulations was proposed. Effects of drug loading percentage (A), carriers' ratio (B), method of preparation (C), and their interactions on percent MX dissolved after 10 and 30 min (Q_10min & Q_30min) from fresh and stored samples were studied in distilled water. The considered levels were 2.5%, 5.0%, and 7.5% (factor A), three ratios of Soluplus®/Poloxamer-407 (factor B). Physical mixture (PM), fusion method (FM), and hot-melt-extrusion (HME) were considered factor (C). Stability studies were carried out for 3 months under stress conditions. The proposed optimization design was validated by 3-extra checkpoints formulations. The optimized formulation was selected via numerical optimization and investigated by DSC, XRD, PLM, and in vitro dissolution study. Results showed that HME technique gave the highest MX dissolution rate compared to other techniques (FM & PM). At constant level of factor (C), the amount of MX dissolved increased by decreasing MX loading and increasing Soluplus in carriers' ratio. Actual responses of the optimized formulation were in close consistency with predicted data. Amorphous form of MX in the optimized formulation was proved by DSC, XRD, and PLM. Selected factors and their levels of the optimization design were significantly valuable for demonstrating and adapting the expected formulation characteristics for rapid dissolution of MX (Q_10min= 89.09%) from fresh and stored samples.

Phase separation in surfactant-containing amorphous solid dispersions: Orthogonal analytical methods to probe the effects of surfactants on morphology and phase composition

Amorphous-amorphous phase separation (AAPS) is an important phase transition process for amorphous solid dispersion (ASD) performance both in terms of drug release as well as physical and chemical stability during storage. Addition of surfactants to ASD systems can impact both of these processes. One possible mechanism through which surfactants affect ASD performance is via their impact on AAPS. Unfortunately, despite their increasing usage in ASD formulations, the effect of surfactant on AAPS is still poorly understood, and there are limited analytical techniques that provide microstructural and composition information about phase separated ASDs. In this study, the impact of four surfactants (sodium dodecyl sulfate, Tween 80, Span 20 and Span 85) on water-induced phase separation in ASDs formulated with ritonavir and polyvinylpyrrolidone/vinyl acetate (PVPVA) was investigated using a variety of orthogonal analytical methods. Transparent films of ASDs with different compositions were prepared by spin coating. Fluorescence confocal microscopy in combination with an in situ humidity chamber was used to monitor the kinetics and morphology of phase separation following exposure to high relative humidity. Optical photothermal IR analysis of phase separated films enabled characterization of domain composition and surfactant distribution. Liquid-liquid phase separation concentration, zeta potential and solution nuclear magnetic resonance spectroscopy measurements enabled interpretation of interaction with and partition of surfactants into the drug-rich phase. It was found that phase separation kinetics and morphology were notably changed by the surfactants. Further, the surfactants showed different affinities for the drug-rich versus the aqueous/polymer-rich phases. The employed analytical techniques were found to be complementary in providing insight into surfactant location in phase separated systems. This study highlights the complexity of phase separation, especially in the presence of surfactants, and provides a foundation to understand the impact of AAPS on ASD performance.

Solid Dispersion Formulations by FDM 3D Printing-A Review

Additive manufacturing (AM) is revolutionizing the way medicines are designed, manufactured, and utilized. Perhaps, AM appears to be ideal for the fit-for-purpose manufacturing of medicines in contrast to the several disadvantages associated with the conventional fit-for-all mass production that accounts for less than 50% of pharmacotherapeutic treatment/management of diseases especially among children and elderly patients, as well as patients with special needs. In this review, we discuss the current trends in the application of additive manufacturing to prepare personalized dosage forms on-demand focusing the attention on the relevance of coupling solid dispersion with FDM 3D printing. Combining the two technologies could offer many advantages such as to improve the solubility, dissolution, and oral bioavailability of poorly soluble drugs in tandem with the concept of precision medicine and personalized dosing and to address the dilemma of commercial availability of FDM filaments loaded with Class II and/or Class IV drugs. However, thermal treatment especially for heat-sensitive drugs, regulatory, and ethical obligations in terms of quality control and quality assurance remain points of concern. Hence, a concerted effort is needed between the scientific community, the pharmaceutical industries, the regulatory agencies, the clinicians and clinical pharmacists, and the end-users to address these concerns.

Hot-melt extrudability of amorphous solid dispersions of flubendazole-copovidone: An exploratory study of the effect of drug loading and the balance of adjuvants on extrudability and dissolution

The FDA-approved anthelmintic flubendazole has shown potential to be repositioned to treat cancer and dry macular degeneration; however, its poor water solubility limits its use. Amorphous solid dispersions may overcome this challenge, but the balance of excipients may impact the preparation method and drug release. The purpose of this study was to evaluate the influence of adjuvants and drug loading on the development of an amorphous solid dispersion of flubendazole-copovidone by hot-melt extrusion. The drug, copovidone, and adjuvants (magnesium stearate and hydroxypropyl cellulose) mixtures were statistically designed, and the process was performed in a twin-screw extruder. The study showed that flubendazole and copovidone mixtures were highly extrudable, except when drug loading was high (>40%). Furthermore, magnesium stearate positively impacted the extrusion and was more effective than hydroxypropyl cellulose. The extruded materials were evaluated by modulated differential scanning calorimetry and X-ray powder diffraction, obtaining positive amorphization and physical stability results. Pair distribution function analysis indicated the presence of drug-rich domains with medium-range order structure and no evidence of polymer-drug interaction. All extrudates presented faster dissolution (HCl, pH 1.2) than pure flubendazole, and both adjuvants had a notable influence on the dissolution rate. In conclusion, hot-melt extrusion may be a viable option to obtain stable flubendazole:copovidone amorphous dispersions.

Impact of Polymer Type on Thermal Degradation of Amorphous Solid Dispersions Containing Ritonavir

High-temperature exposure during hot melt extrusion processing of amorphous solid dispersions may result in thermal degradation of the drug. Polymer type may influence the extent of degradation, although the underlying mechanisms are poorly understood. In this study, the model compound, ritonavir (T_m = 126 °C), undergoes thermal degradation upon high-temperature exposure. The extent of degradation of ritonavir in amorphous solid dispersions (ASDs) formulated with poly(vinylpyrrolidone) (PVP), poly(vinylpyrrolidone) vinyl acetate copolymer (PVP/VA), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and hydroxypropyl methylcellulose (HPMC) following isothermal heating and hot melt extrusion was evaluated, and mechanisms related to molecular mobility and intermolecular interactions were assessed. Liquid chromatography-mass spectrometry (LC-MS/MS) studies were used to determine the degradation products and pathways and ultimately the drug-polymer compatibility. The dominant degradation product of ritonavir was the result of a dehydration reaction, which then catalyzed a series of hydrolysis reactions to generate additional degradation products, some newly reported. This reaction series led to accelerated degradation rates with protic polymers, HPMCAS and HPMC, while ASDs with aprotic polymers, PVP and PVP/VA, had reduced degradation rates. This work has implications for understanding mechanisms of thermal degradation and drug-polymer compatibility with respect to the thermal stability of amorphous solid dispersions.

Sodium Caseinate and Acetylated Mung Bean Starch for the Encapsulation of Lutein: Enhanced Solubility and Stability of Lutein

Lutein is a kind of vital carotenoid with high safety and significant advantages in biological functions. However, poor water solubility and stability of lutein have limited its application. This study selected different weight ratios of sodium caseinate to acetylated mung bean starch (10:0, 9:1, 7:3, 5:5, 3:7, 1:9, and 0:10) to prepare lutein emulsions, and the microcapsules were produced by spray drying technology. The microstructure, physicochemical properties, and storage stability of microcapsules were investigated. The results show that the emulsion systems were typical non-Newtonian fluids. Lutein microcapsules were light yellow fine powder with smooth and relatively complete particle surface. The increase of sodium caseinate content led to the enhanced emulsion effect of the emulsion and the yield and solubility of microcapsules increased, and wettability and the average particle size became smaller. The encapsulation efficiency of lutein microcapsules ranged from 69.72% to 89.44%. The thermal characteristics analysis showed that the endothermic transition of lutein microcapsules occurred at about 125 °C. The microcapsules with sodium caseinate as single wall material had the worst stability. Thus, it provides a reference for expanding the application of lutein in food, biological, pharmaceutical, and other industries and improving the stability and water dispersion of other lipid-soluble active ingredients.

Improved Bioavailability of Poorly Water-Soluble Drug by Targeting Increased Absorption through Solubility Enhancement and Precipitation Inhibition

Itraconazole (ITZ) is a class II drug according to the biopharmaceutical classification system. Its solubility is pH 3-dependent, and it is poorly water-soluble. Its pKa is 3.7, which makes it a weak base drug. The aim of this study was to prepare solid dispersion (SD) pellets to enhance the release of ITZ into the gastrointestinal environment using hot-melt extrusion (HME) technology and a pelletizer. The pellets were then filled into capsules and evaluated in vitro and in vivo. The ITZ changed from a crystalline state to an amorphous state during the HME process, as determined using DSC and PXRD. In addition, its release into the gastrointestinal tract was enhanced, as was the level of ITZ recrystallization, which was lower than the marketed drug (Sporanox^®), as assessed using an in vitro method. In the in vivo study that was carried out in rats, the AUC_0-48h of the commercial formulation, Sporanox^®, was 1073.9 ± 314.7 ng·h·mL^-1, and the bioavailability of the SD pellet (2969.7 ± 720.6 ng·h·mL^-1) was three-fold higher than that of Sporanox^® (*** p < 0.001). The results of the in vivo test in beagle dogs revealed that the AUC_0-24h of the SD-1 pellet (which was designed to enhance drug release into gastric fluids) was 3.37 ± 3.28 μg·h·mL^-1 and that of the SD-2 pellet (which was designed to enhance drug release in intestinal fluids) was 7.50 ± 4.50 μg·h·mL^-1. The AUC of the SD-2 pellet was 2.2 times higher than that of the SD-1 pellet. Based on pharmacokinetic data, ITZ would exist in a supersaturated state in the area of drug absorption. These results indicated that the absorption area is critical for improving the bioavailability of ITZ. Consequently, the bioavailability of ITZ could be improved by inhibiting precipitation in the absorption area.

Cellulose derivatives as effective recrystallization inhibitor for ternary ritonavir solid dispersions: In vitro-in vivo evaluation

Amorphous solid dispersions (ASDs) are regarded as one of the most promising techniques for poorly-soluble active pharmaceutical ingredients (API). However, the thermodynamic instability of ASDs at supersaturated state makes them easy to recrystallize in aqueous media. In this study, ritonavir (RTV) was selected as a model drug for evaluating the solubility enhancement and recrystallization inhibition effect of various cellulose derivatives and the combinations of them with typical surfactants. Combination of HPMCAS-HF/SLS was filtrated for preparing ternary RTV solid dispersions (RTV SD) via solvent evaporation method. RTV SD exhibited enhanced dissolution manner, while the oral bioavailability of RTV SD was equivalent with the Reference Standard Norvir® but increased significantly compared to the ternary physical mixture. Thus, the ternary SD system might be promisingly employed as efficient drug delivery system for RTV, while the HPMCAS-HF/SLS combination could be recommended as effective excipient for fabricating steady solid dispersions loading poorly soluble API.

Amorphous solid dispersions of cyclosporine A with improved bioavailability prepared via hot melt extrusion: Formulation, physicochemical characterization, and in vivo evaluation

In this study, the amorphous solid dispersions of cyclosporine A (CsA-ASDs) were prepared by hot melt extrusion (HME) with PVP K12 as carrier to improve the oral bioavailability of CsA. The polymers were screened by solubilization and recrystallization inhibition experiments, then the CsA-ASDs were prepared with optimized technological parameters and characterized on thermodynamics and morphology. The results showed that CsA was dispersed among PVP K12 as amorphous form in CsA-ASDs, and the infrared spectrum testified that there was possible hydrogen bond interaction between CsA and PVP K12. The in vivo pharmacokinetics of CsA formulations in rats were analyzed via LC-MS. The AUC of CsA-ASD tablets increased by 7.3 times compared to CsA bulk powder and 3.1 times in contrast to CsA-PM tablets, respectively. The experiment proved that CsA-ASD tablets significantly improved the dissolution and absorption of the drug. This study had a reference value for the bioavailability improvement of oral CsA preparations.

Investigating the Potential Plasticizing Effect of Di-Carboxylic Acids for the Manufacturing of Solid Oral Forms with Copovidone and Ibuprofen by Selective Laser Sintering

In selective laser sintering (SLS), the heating temperature is a critical parameter for printability but can also be deleterious for the stability of active ingredients. This work aims to explore the plasticizing effect of di-carboxylic acids on reducing the optimal heating temperature (OHT) of polymer powder during SLS. First, mixtures of copovidone and di-carboxylic acids (succinic, fumaric, maleic, malic and tartaric acids) as well as formulations with two forms of ibuprofen (acid and sodium salt) were prepared to sinter solid oral forms (SOFs), and their respective OHT was determined. Plasticization was further studied by differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). Following this, the printed SOFs were characterized (solid state, weight, hardness, disintegration time, drug content and release). It was found that all acids (except tartaric acid) reduced the OHT, with succinic acid being the most efficient. In the case of ibuprofen, only the acid form demonstrated a plasticizing effect. DSC and FTIR corroborated these observations showing a decrease in the glass transition temperature and the presence of interactions, respectively. Furthermore, the properties of the sintered SOFs were not affected by plasticization and the API was not degraded in all formulations. In conclusion, this study is a proof-of-concept that processability in SLS can improve with the use of di-carboxylic acids.

Recent studies on the processes and formulation impacts in the development of solid dispersions by hot-melt extrusion

Industrial-scale pharmaceutical applications still face many challenges in overcoming the low absorption and bioavailability of poorly water-soluble drugs. Hot-melt extrusion has emerged as a promising approach with continuous processing on an industrial scale for the preparation of drug delivery systems. Many reviews have mentioned the potential applications, processes, principles and advantages and disadvantages of hot-melt extrusion in the pharmaceutical industry. However, a focus on the recent progress of hot-melt extrusion, which investigates the impacts of processes and formulations of solid dispersions of poorly water-soluble drugs, is missing. In this review, various factors, including polymers, drug properties, additives and surfactants, in solid dispersion SD formulations by hot-melt extrusion will be discussed. Moreover, the effects of the hot-melt extrusion process on the physicochemical properties of solid dispersions will be mentioned. The utilization of molecular interactions in hot-melt extrusion to improve drug stability will also be described. Overall, this summary of recent studies on solid dispersion by hot-melt extrusion will provide perspectives and effectiveness for the development of formulations containing poorly water-soluble drugs.

Electrospun poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) nanofibers for the controlled release of cilostazol

Drug delivery devices are attractive alternatives to drugs usually orally administrated. Therefore, this work aimed to produce PLA/PBAT-based nanofibers for the controlled release of cilostazol, evaluating the effect of different drug concentrations (20 and 30%) over the properties of the fibers. The fibers were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), x-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG/DTG), and mechanical analysis. SEM results indicated a high concentration of drug crystals on the surface of the fibers that contained 20% of cilostazol. These fibers were also thinner, more crystalline, less thermally stable, and less fragile in comparison to the fibers containing 30% of cilostazol, according to the XRD, DSC, TG/DTG, and mechanical results. The controlled release assays indicated that the fibers containing 20% of cilostazol would be attractive for short-term releases, reaching the equilibrium after approximately 6 h, while the ones containing 30% would ensure a slower release (~ 12 h). Despite the differences, both fibers would improve and enhance the efficiency of the treatment, and they would also prevent possible side effects caused by the drug to the gastric system.

Multifunctional Role of Polyvinylpyrrolidone in Pharmaceutical Formulations

Polyvinylpyrrolidone (PVP), a non-ionic polymer, has been employed in multifarious fields such as paper, fibers and textiles, ceramics, and pharmaceutics due to its superior properties. Especially in pharmacy, the properties of inertness, non-toxicity, and biocompatibility make it a versatile excipient for both conventional formulations and novel controlled or targeted delivery systems, serving as a binder, coating agent, suspending agent, pore-former, solubilizer, stabilizer, etc. PVP with different molecular weights (MWs) and concentrations is used in a variety of formulations for different purposes. In this review, PVP-related researches mainly in recent 10 years were collected, and its main pharmaceutical applications were summarized as follows: (i) improving the bioavailability and stability of drugs, (ii) improving the physicomechanical properties of preparations, (iii) adjusting the release rate of drugs, and (iv) prolonging the in vivo circulation time of liposomes. Most of these applications could be explained by the viscosity, solubility, hydrophilicity, and hydrogen bond-forming ability of PVP, and the specific action mechanisms for each application were also tried to figure out. The effect of PVP on bioavailability improvement establishes it as a promising polymer in the emerging controlled or targeted formulations, attracting growing interest on it. Therefore, given its irreplaceability and tremendous opportunities for future developments, this review aims to provide an informative reference about current roles of PVP in pharmacy for interested readers.

Low Molecular Weight Oligomers of Poly(alkylene succinate) Polyesters as Plasticizers in Poly(vinyl alcohol) Based Pharmaceutical Applications

The plasticizing effect of three low molecular weight oligomers of aliphatic poly(alkylene succinate) polyesters, namely poly(butylene succinate) (PBSu), poly(ethylene succinate) (PESu), and poly(propylene succinate) (PPSu), on partially hydrolyzed poly(vinyl alcohol) (PVA) used in melt-based pharmaceutical applications, was evaluated for the first time. Initially, the three aliphatic polyesters were prepared by the melt polycondensation process and characterized by differential scanning calorimetry (DSC), ¹H NMR, intrinsic viscosity, and size exclusion chromatography (SEC). Subsequently, their effect on the thermophysical and physicochemical properties of PVA was thoroughly evaluated. According to the obtained results, PVA was completely miscible with all three polyesters, while PESu induced PVA’s thermal degradation, with the phenomenon starting from ~220 °C, in contrast to PBSu and PPSu, where a thermal profile similar to PVA was observed. Furthermore, molecular interactions between PVA and the prepared poly(alkylene succinate) polyesters were revealed by DSC, ATR-FTIR, and molecular dynamics simulations. Finally, melt flow index (MFI) measurements showed that, in contrast to PBSu, the use of PESu or PPSu significantly improved PVA’s melt flow properties. Hence, according to findings of the present work, only the use of low molecular weight PPSu is suitable in order to reduce processing temperature of PVA and improve its melt flow properties (plasticizing ability) without affecting its thermal decomposition.

Selective Laser Sintering 3-Dimensional Printing as a Single Step Process to Prepare Amorphous Solid Dispersion Dosage Forms for Improved Solubility and Dissolution Rate

This study reports the development of ritonavir-copovidone amorphous solid dispersions (ASDs) and dosage forms thereof using selective laser sintering (SLS) 3-dimensional (3-D) printing in a single step, circumventing the post-processing steps required in common techniques employed to make ASDs. For this study, different drug loads of ritonavir with copovidone were processed at varying processing conditions to understand the impact, range, and correlation of these parameters for successful ASD formation. Further, ASDs characterized using conventional and advanced solid-state techniques including wide-angle X-ray scattering (WAXS), solid-state nuclear magnetic resonance (ssNMR), revealed the full conversion of the crystalline drug to its amorphous form as a function of laser-assisted selective fusion in a layer-by-layer manner. It was observed that an optimum combination of the powder flow properties, surface temperature, chamber temperature, laser speed, and hatch spacing was crucial for successful ASD formation, any deviations resulted in print failures or only partial amorphous conversion. Moreover, a 21-fold increase in solubility was demonstrated by the SLS 3-D printed tablets. The results confirmed that SLS 3-D printing can be used as a single-step platform for creating ASD-based pharmaceutical dosage forms with a solubility advantage.

Innovations in Thermal Processing: Hot-Melt Extrusion and KinetiSol® Dispersing

Thermal processing has gained much interest in the pharmaceutical industry, particularly for the enhancement of solubility, bioavailability, and dissolution of active pharmaceutical ingredients (APIs) with poor aqueous solubility. Formulation scientists have developed various techniques which may include physical and chemical modifications to achieve solubility enhancement. One of the most commonly used methods for solubility enhancement is through the use of amorphous solid dispersions (ASDs). Examples of commercialized ASDs include Kaletra®, Kalydeco®, and Onmel®. Various technologies produce ASDs; some of the approaches, such as spray-drying, solvent evaporation, and lyophilization, involve the use of solvents, whereas thermal approaches often do not require solvents. Processes that do not require solvents are usually preferred, as some solvents may induce toxicity due to residual solvents and are often considered to be damaging to the environment. The purpose of this review is to provide an update on recent innovations reported for using hot-melt extrusion and KinetiSol® Dispersing technologies to formulate poorly water-soluble APIs in amorphous solid dispersions. We will address development challenges for poorly water-soluble APIs and how these two processes meet these challenges.

Enhancing the Solubility of Curcumin Using a Solid Dispersion System with Hydroxypropyl-β-Cyclodextrin Prepared by Grinding, Freeze-Drying, and Common Solvent Evaporation Methods

Cyclodextrins (CDs) and their derivatives significantly increase drug solubility by forming drug/CD complexes known as solid dispersions (SDs), which consist of an inclusion complex (IC), where the drug is entrapped within the CD cavity, and a non-IC. Here, the SDs of curcumin (CUR) and hydroxypropyl-β-cyclodextrin (HPβCD) were prepared using the grinding, freeze-drying (FD), and common solvent evaporation (CSE) methods and were physicochemically characterized using solubility, powder X-ray diffraction, Fourier transform infrared, differential scanning calorimetry, and dissolution studies. The second or higher order complex of CUR-HPβCD indicated the co-existence of ICs and non-ICs known as the SD system. When comparing the soluble drug amount with CUR crystals, the solubility of SDs was enhanced by up to 299-, 180-, and 489-fold, corresponding to the ground mixtures (GMs), freeze-drying mixtures (FDs), and common solvent evaporation mixtures (CSEs), respectively. The total transformation into the amorphous phase of CUR was observed in GMs and in CSE12, CSE14, and CSE18. The drug was well dispersed within HPβCD in GMs and CSEs, suggesting the formation of hydrogen bonds between CUR and HPβCD, whereas the dispersed behavior of FDs was similar to that of physical mixtures. In SDs, the melting temperature of CUR was in an increased order of CUR in 1:2 ICs, CUR in 1:1 ICs, and CUR crystals. The dissolution rate of CUR was positively improved as the amount of HPβCD in SDs increased. The SD system consisting of CUR and HPβCD significantly increased the drug solubility compared to ICs.

Aqueous Dissolution and Dispersion Behavior of Polyvinylpyrrolidone Vinyl Acetate-based Amorphous Solid Dispersion of Ritonavir Prepared by Hot-Melt Extrusion with and without Added Surfactants

In this study, the lack of complete drug release from amorphous solid dispersions (ASDs), as observed in most published reports, was investigated. ASDs with 20% ritonavir were prepared by HME using polyvinylpyrrolidone vinyl acetate (PVPVA) alone and in combination with 10% poloxamer 407 or Span 20 as carriers. It was established by the film casting technique that ritonavir was molecularly dispersed in formulations, and accelerated stability testing confirmed that extrudates were physically stable. Dissolution of ASDs (100-mg ritonavir equivalent) was performed in 250 mL 0.01 N HCl (pH 2), pH 6.8 phosphate buffer and FeSSIF-V2. Drug concentrations were measured by filtration through 0.45-μm pores and in unfiltered media; the latter gave total amounts of drug present in dissolution media, both as solution and dispersion. Because of low solubility, ritonavir did not dissolve completely in aqueous media. Rather, it formed supersaturated solutions, and the excess drug dispersed in the oily amorphous form with low particle sizes that could crystallize with time. Due to higher drug solubility, the dissolved drug in FeSSIF-V2 was much higher than that in the phosphate buffer. Complete drug release could be observed by accounting for drug both in solution and as phase-separated dispersion. Thus, the present study provides a complete picture of in vitro drug dissolution and dispersion from ASDs.

Hybridized nanoamorphous micellar dispersion using a QbD-DM3 linked rational product design strategy for ritonavir: A BCS IV drug

A QbD-DM³ linked rational product design strategy was adopted to create a hybridized ritonavir (RTV, BCS Class IV) nanoamorphous micellar dispersion (RTV-NAD). A DM³ research strategy was employed in conjunction with the quality-by-design spaces, and quality target product profile to link the critical material attributes and critical process parameters to the quality target product profile's critical product attributes QbD elements. A Box-Behnken design and multivariate analysis using multiple linear regression and partial least squares provided data analysis. The hybridized strategy leveraged three different mechanisms to increase RTV's solubility and four mechanisms to increase its dissolution rate. Statistically significant models were generated for critical product attributes: particle size (p = 0.0000, R² adjusted = 0.9513), polydispersity index (p = 0.0002, R² adjusted = 0.6398), zeta potential (p = 0.0000, R² adjusted = 0.9744), and drug loading on a dry basis (p = 0.0000, R² adjusted = 0.9951). The impact of drug concentration, Soluplus® concentration, and solvent:antisolvent ratio, their interactions and square effects on the critical product attributes were assessed by multivariate analysis. The QbD optimal formulation was determined for RTV-NAD. Multiple linear regression and partial least squares computational predictability was evaluated using three verification batches. The prediction error for critical product attributes was <5%. RTV-NAD and ritonavir microsuspension were characterized by x-ray diffraction and in-vitro dissolution studies. X-ray diffraction confirmed the amorphous nature of the RTV-NAD. RTV-NAD exhibited a 'spring-hover' dissolution profile at pH 4.5. At pH 6.8, a classic 'spring-parachute' dissolution behavior was observed.

Polymer/lipid interplay in altering in vitro supersaturation and plasma concentration of a model poorly soluble drug

Supersaturation drug delivery system (SDDS) based on amorphous solid dispersion (ASD) is a widely used strategy to improve oral absorption of poorly water-soluble drugs by achieving a supersaturated state where drug concentration is significantly higher than drug solubility. However, dissolved drugs tend to recrystallize in gastrointestinal (GI) tract if without effective stabilizing excipients. In this paper, well-recognized polymer (polyvinylpyrrolidone, PVP) and lipid (phosphatidylcholine, PC) excipients are combined as ASD carrier, aiming at investigating the effects on evolution of in vitro supersaturation and in vivo plasma concentration of a model poorly soluble drug indomethacin (IND). Fundamental aspects including polymer/lipid composition ratio, drug loading (DL) degree and administration dose were investigated. The in vitro dissolution profiles of ASDs were assessed by supersaturation degree, duration, maximum achievable drug concentration and dose-normalized efficiency, and correlated with in vivo pharmacokinetic data. Results showed that both in vitro and in vivo concentration-time profiles of IND were significantly varying with abovementioned factors. Solution viscosity, solid-state properties and morphology of ASDs were related to the results. This study revealed fundamental mechanisms of PVP/PC mixture effect on IND supersaturation and oral bioavailability, demonstrating that polymer/lipid mixture could be used as a promising carrier to alter supersaturation profile and oral bioavailability of SDDS products.

Enhanced Oral Bioavailability of Celecoxib Nanocrystalline Solid Dispersion based on Wet Media Milling Technique: Formulation, Optimization and In Vitro/In Vivo Evaluation

Celecoxib (CLX), a selective COX-2 inhibitor, is a biopharmaceutics classification system (BCS) class II drug with its bioavailability being limited by thepoor aqueoussolubility. The purpose of this study was to develop and optimize CLX nanocrystalline(CLX-NC) solid dispersion prepared by the wet medium millingtechnique combined with lyophilizationto enhance oral bioavailability. In formulation screening, the resulting CLX-NC usingpolyvinylpyrrolidone (PVP) VA64 and sodiumdodecyl sulfate (SDS) as combined stabilizers showed the minimum particle size and a satisfactory stability. The formulation and preparation processwere further optimized by central composite experimentaldesign with PVP VA64 concentration (X₁), SDS concentration (X₂) and milling times (X₃) as independent factors and particle size (Y₁), polydispersity index (PDI, Y₂) and zeta potential (Y₃) as response variables. The optimal condition was determined as a combination of 0.75% PVP VA64, 0.11% SDS with milling for 90 min.The particle size, PDI and zeta potential of optimized CLX-NC were found to be 152.4 ± 1.4 nm, 0.191 ± 0.012 and −34.4 ± 0.6 mV, respectively. The optimized formulation showed homogeneous rod-like morphology as observed by scanning electron microscopy and was in a crystalline state as determined by differential scanning calorimetry and powder X-ray diffraction. In a storage stability study, optimized CLX-NC exhibited an excellent physical stability during six months’ storage at both the refrigeration and room conditions. In vivo pharmacokinetic research in Sprague-Dawley ratsdisplayed that C_max and AUC_0–∞ of CLX-NC were increased by 2.9 and 3.1 fold, compared with physical mixture. In this study, the screening and optimizing strategy of CLX-NC formulation represents a commercially viable approach forenhancing the oral bioavailability of CLX.

Solubility and bioavailability enhancement study of lopinavir solid dispersion matrixed with a polymeric surfactant - Soluplus

As a biopharmaceutical classification system Class IV drug, lopinavir (LPV) shows relatively poor water solubility and permeation in vivo. In the study, we developed novel solid dispersions (SD) of LPV to improve its bioavailability and to describe their overall behaviors. By employing solvent evaporation for a preliminary formulation screening, the SDs of LPV-polymer-sorbitan monolaurate (SBM, as the wetting agent) at 1:4:0.4 (w/w) dramatically enhanced the LPV dissolution in a non-sink medium, and then hot-melt extrusion (HME) was applied to improve the dissolution further. A hydrophilic polymer - Kollidon VA 64 (VA64) and a polymeric surfactant Soluplus were employed as matrix respectively in the optimized formulations. The dissolution profiles of extrudates were significantly higher than those of SDs prepared with solvent-evaporation method. It was attributed to the stronger intermolecular interactions between LPV and the polymers in the HME process, which was also supported by the stability analysis after 6 months storage under 25 °C/60% RH. The differential scanning calorimetry, fourier transform infrared spectroscopy and equilibrium studies showed VA64 only created hydrogen bonding (H-bond) with LPV, but Soluplus generated both H-bond and micelle thanks to its amphiphilic structure. In addition, the bioavailability of LPV in Soluplus matrixed extrudate was 1.70-fold of VA64 matrixed extrudate and 3.70-fold of LPV crystal. In situ permeability and Caco-2 cell transport studies revealed that Soluplus significantly enhanced the permeability of LPV through rat intestine and Caco-2 cell monolayers by P-glycoprotein (P-gp) inhibition. Herein, Soluplus matrixed extrudate improved the LPV bioavailability through three mechanisms: H-bond with LPV, micelle formation in water and P-gp inhibition in vivo. These unique advantages of Soluplus suggested it is a promising carrier for poorly water soluble drugs, especially the substrates of P-gp.

Overview of the Manufacturing Methods of Solid Dispersion Technology for Improving the Solubility of Poorly Water-Soluble Drugs and Application to Anticancer Drugs

Approximately 40% of new chemical entities (NCEs), including anticancer drugs, have been reported as poorly water-soluble compounds. Anticancer drugs are classified into biologic drugs (monoclonal antibodies) and small molecule drugs (nonbiologic anticancer drugs) based on effectiveness and safety profile. Biologic drugs are administered by intravenous (IV) injection due to their large molecular weight, while small molecule drugs are preferentially administered by gastrointestinal route. Even though IV injection is the fastest route of administration and ensures complete bioavailability, this route of administration causes patient inconvenience to visit a hospital for anticancer treatments. In addition, IV administration can cause several side effects such as severe hypersensitivity, myelosuppression, neutropenia, and neurotoxicity. Oral administration is the preferred route for drug delivery due to several advantages such as low cost, pain avoidance, and safety. The main problem of NCEs is a limited aqueous solubility, resulting in poor absorption and low bioavailability. Therefore, improving oral bioavailability of poorly water-soluble drugs is a great challenge in the development of pharmaceutical dosage forms. Several methods such as solid dispersion, complexation, lipid-based systems, micronization, nanonization, and co-crystals were developed to improve the solubility of hydrophobic drugs. Recently, solid dispersion is one of the most widely used and successful techniques in formulation development. This review mainly discusses classification, methods for preparation of solid dispersions, and use of solid dispersion for improving solubility of poorly soluble anticancer drugs.