Combining amorphous solid dispersions for improved kinetic solubility of posaconazole simultaneously released from soluble PVP/VA64 and an insoluble ammonio methacrylate copolymer

A review on design rules for formulating amorphous solid dispersions based on drug-polymer interactions in aqueous environment

Amorphous solid dispersions (ASDs) are multi-component formulations in which a drug is molecularly dispersed in a carrier. ASDs undergo complex dissolution mechanisms to generate and sustain a supersaturated state of poorly soluble drugs. The link between enhanced solubility, supersaturation stability and drug-polymer interaction (DPI) is critical for the rational design of ASDs. The key mechanism responsible for a high bioavailability is the evolution of supersaturation during the dissolution of ASDs which is also the driving force for drug precipitation. A critical determinant of robust supersaturation generation and stability during dissolution is the molecular interaction between the drug and polymer. Characterization of DPI in a solution state is, however, challenging because of the poor hydrodynamic resolution of the techniques, traditionally used in solid-state analysis. Further, the dissolution conditions, such as the choice of buffer, pH and ionic strength may complicate the analyses and predictions. The role of DPI is a poorly understood aspect of ASD dissolution and therefore is an active area of research. DPI is critical for understanding the design rules for formulating an optimal ASD formulation. The review focuses on different aspects of DPI to stabilize the supersaturated state of a drug during the dissolution of ASDs.

Investigation of aerosol jet printing for the preparation of solid dosage forms

Oral drug delivery remains the preferred method of drug administration but due to poor solubility many active pharmaceutical ingredients (APIs) are ill suited to this. A number of methods to improve solubility of poorly soluble Biopharmaceutical Classification System (BCS) Class II drugs already exist but there is a lack of scalable, flexible methods. As such the current study applies the innovative technique of aerosol jet printing to increase the dissolution capabilities of a Class II drug in a manner which permits flexibility to allow dosage form tailoring. Aerosol jet printing provided a high degree of control allowing effective scaling, by size and layering, and control over drug distribution. Aerosol jet printing of pure active pharmaceutical ingredient (fenofibrate) resulted in crystalline material but as polymer excipient content was increased, morphological changes occurred and a fully amorphous product was generated on inclusion of 75 % (w/w solute) polymer content or above. This amorphous product has been found to exhibit a 10-fold increase in drug dissolution relative to comparable physical mixtures. In conclusion, aerosol jet printing is a novel and effective, scalable method providing improved dissolution coupled with high spatial precision and warrants further investigation.

ω-Carboxyl terminated cellulose esters are effective crystallization inhibitors for challenging drugs

Polymeric additives are widely used to delay drug crystallization from supersaturated solutions, which is critical for enhancing oral bioavailability by amorphous solid dispersion (ASD). The efficacy of these polymers relies on their capacity to inhibit nucleation and subsequent crystal growth. Drug nucleation is pivotal to crystallization; therefore, effective polymers are essential for suppressing nucleation from supersaturated solutions. We studied the performance of cellulose ω-carboxyalkanoates designed as crystallization inhibitors by measuring their influence on nucleation induction times of poorly soluble drugs celecoxib, posaconazole, and enzalutamide, from supersaturated solutions. In the absence of polymers, crystallization occurred within 5 to 15 minutes for all three drugs. Polymer hydrophobicity strongly influenced effectiveness in crystallization inhibition. Hydrophobic polymers prolonged induction times for up to 8 hours, while hydrophilic polymers were less effective, except for cellulose acetate glutarate (CA1.18-GA1.21; degrees of substitution acetate 1.18, glutarate 1.21). The cellulose ω-carboxyalkanoates had glass transition temperatures well above 100 °C, outstanding for ASD stability requirements. We investigated the impact of these designed polymers on surface tension and found that it only weakly influenced crystallization inhibition. Among the nine crafted cellulose derivatives, water-soluble CA1.18-GA1.21 emerged as a highly promising ASD polymer, preventing crystallization for 2-8 hours for all fast-crystallizing model compounds.

The Excellent Chemical Interaction Properties of Poloxamer and Pullulan with Alpha Mangostin on Amorphous Solid Dispersion System: Molecular Dynamics Simulation

BACKGROUND

Alpha mangostin (AM) has demonstrated significant potential as an anticancer agent, owing to its potent bioactivity. However, its clinical application is limited by poor solubility, which hampers its bioavailability and effectiveness. Amorphous solid dispersion (ASD) presents a promising technique to enhance the solubility and stability of AM. Molecular dynamics simulation offers a rapid, efficient, and precise method to evaluate and optimize ASD formulations before production.

AIM OF STUDY

In this study, we conducted molecular dynamics simulations to explore the ASD development of AM with poloxamer and pullulan.

RESULT

Our results revealed that AM-poloxamer complexes exhibit superior interaction characteristics compared to AM-pullulan, with a 1:5 ratio of AM to poloxamer and a cooling rate of 1 °C/ns demonstrating the most favorable outcomes. This combination showed enhanced hydrogen bonding, a more compact molecular structure, and higher stability, making it the optimal choice for ASD formulation.

CONCLUSION

The integration of molecular dynamics simulation into ASD development significantly accelerates the formulation process and provides critical insights into achieving a stable and effective AM dispersion. The AM-poloxamer complex, particularly at a 1:5 ratio with a 1 °C/ns cooling rate, offers the best potential for improving AM solubility and therapeutic efficacy.

Polymorphism and Pharmacological Assessment of Carbamazepine

This work provides insight into carbamazepine polymorphs (Forms I, II, III, IV, and V), with reports on the cytoprotective, exploratory, motor, CNS-depressant, and anticonvulsant properties of carbamazepine (CBZ), carbamazepine formulation (CBZ-F), topiramate (TOP), oxcarbazepine (OXC), and diazepam (DZP) in mice. Structural analysis highlighted the significant difference in molecular conformations, which directly influence the physicochemical properties; and density functional theory description provided indications about CBZ reactivity and stability. In addition to neuron viability assessment in vitro, animals were treated orally with vehicle 10 mL/kg, as well as CBZ, CBZ-F, TOP, OXC, and DZP at the dose of 5 mg/kg and exposed to open-field, rotarod, barbiturate sleep induction and pentylenetetrazol (PTZ 70 mg/kg)-induced seizure. The involvement of GABAergic mechanisms in the activity of these drugs was evaluated with the intraperitoneal pretreatment of flumazenil (2 mg/kg). The CBZ, CBZ-F, and TOP mildly preserved neuronal viability. The CBZ-F and the reference AEDs potentiated barbiturate sleep, altered motor activities, and attenuated PTZ-induced convulsion. However, flumazenil pretreatment blocked these effects. Additional preclinical assessments could further establish the promising utility of CBZ-F in clinical settings while expanding the scope of AED formulations and designs.

Preparation, Characterization and Evaluation of Nintedanib Amorphous Solid Dispersions with Enhanced Oral Bioavailability

The dissolution and bioavailability challenges posed by poorly water-soluble drugs continue to drive innovation in pharmaceutical formulation design. Nintedanib (NDNB) is a typical BCS class II drug that has been utilized to treat idiopathic pulmonary fibrosis (IPF). Due to the low solubility, its oral bioavailability is relatively low, limiting its therapeutical effectiveness. It is crucial to enhance the dissolution and the oral bioavailability of NDNB. In this study, we focused on the preparation of amorphous solid dispersions (ASD) using hot melt extrusion (HME). The formulation employed Kollidon® VA64 (VA64) as the polymer matrix, blended with the NDNB at a ratio of 9:1. HME was conducted at temperatures ranging from 80 °C to 220 °C. The successful preparation of ASD was confirmed through various tests including polarized light microscopy (PLM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The in-vitro cumulative release of NDNB-ASD in 2 h in a pH 6.8 medium was 8.3-fold higher than that of NDNB (p < 0.0001). In a pH 7.4 medium, it was 10 times higher (p < 0.0001). In the in-vivo pharmacokinetic experiments, the area under curve (AUC) of NDNB-ASD was 5.3-fold higher than that of NDNB and 2.2 times higher than that of commercially available soft capsules (Ofev®) (p < 0.0001). There was no recrystallization after 6 months under accelarated storage test. Our study indicated that NDNB-ASD can enhance the absorption of NDNB, thus providing a promising method to improve NDNB bioavailability in oral dosages.

Preparation, Characterization, and Oral Bioavailability of Solid Dispersions of Cryptosporidium parvum Alternative Oxidase Inhibitors

The phenylpyrazole derivative 5-amino-3-[1-cyano-2-(3-phenyl-1H-pyrazol-4-yl) vinyl]-1-phenyl-1H-pyrazole-4-carbonitrile (LN002), which was screened out through high-throughput molecular docking for the AOX target, exhibits promising efficacy against Cryptosporidium. However, its poor water solubility limits its oral bioavailability and therapeutic utility. In this study, solid dispersion agents were prepared by using HP-β-CD and Soluplus® and characterized through differential scanning calorimetry, Fourier transform infrared, powder X-ray diffraction, and scanning electron microscopy. Physical and chemical characterization showed that the crystal morphology of LN002 transformed into an amorphous state, thus forming a solid dispersion of LN002. The solid dispersion prepared with an LN002/HP-β-CD/Soluplus® mass ratio of 1:3:9 (w/w/w) exhibited significantly increased solubility and cumulative dissolution. Meanwhile, LN002 SDs showed good preservation stability under accelerated conditions of 25 °C and 75% relative humidity. The complexation of LN002 with HP-β-CD and Soluplus® significantly improved water solubility, pharmacological properties, absorption, and bioavailability.

An empirical predictive model for determining the aqueous solubility of BCS class IV drugs in amorphous solid dispersions

CONTEXT

Determining solubility of drugs is laborious and time-consuming process that may not yield meaningful results. Amorphous solid dispersion (ASD) is a widely used solubility enhancement technique. Predictive models could streamline this process and accelerate the development of oral drugs with improved aqueous solubilities.

OBJECTIVE

This study aimed to develop a predictive model to estimate the solubility of a compound from the ASDs in polymer matrices.

METHODS

ASDs of model drugs (acetazolamide, chlorothiazide, furosemide, hydrochlorothiazide, sulfamethoxazole) with model polymers (PVP, PVPVA, HPMC E5, Soluplus) and a surfactant (TPGS) were prepared using hotmelt process. The prepared ASDs were characterized using DSC, FTIR, and XRD. The aqueous solubility of the model drugs was determined using shake-flask method. Multiple linear regression was used to develop a predictive model to determine aqueous solubility using the molecular descriptors of the drug and polymer as predictor variables. The model was validated using Leave-One-Out Cross-Validation.

RESULTS

The ASDs' drug components were identified as amorphous via DSC and XRD Studies. There were no significant chemical interactions between the model drugs and the polymers based on FTIR studies. The ASDs showed a significant (p < 0.05) improvement in solubility, ranging from a 3-fold to 118-fold, compared with the pure drug. The developed empirical model predicted the solubility of the model drugs from the ASDs containing model polymer matrices with an accuracy greater than 80%.

CONCLUSION

The developed empirical model demonstrated robustness and predicted the aqueous solubility of model drugs from the ASDs of model polymer matrices with an accuracy greater than 80%.

Advancing Drug Delivery Paradigms: Polyvinyl Pyrolidone (PVP)-Based Amorphous Solid Dispersion for Enhanced Physicochemical Properties and Therapeutic Efficacy

BACKGROUND

The current challenge in drug development lies in addressing the physicochemical issues that lead to low drug effectiveness. Solubility, a crucial physicochemical parameter, greatly influences various biopharmaceutical aspects of a drug, including dissolution rate, absorption, and bioavailability. Amorphous solid dispersion (ASD) has emerged as a widely explored approach to enhance drug solubility.

OBJECTIVE

The objective of this review is to discuss and summarize the development of polyvinylpyrrolidone (PVP)-based amorphous solid dispersion in improving the physicochemical properties of drugs, with a focus on the use of PVP as a novel approach.

METHODOLOGY

This review was conducted by examining relevant journals obtained from databases such as Scopus, PubMed, and Google Scholar, since 2018. The inclusion and exclusion criteria were applied to select suitable articles.

RESULTS

This study demonstrated the versatility and efficacy of PVP in enhancing the solubility and bioavailability of poorly soluble drugs. Diverse preparation methods, including solvent evaporation, melt quenching, electrospinning, coprecipitation, and ball milling are discussed for the production of ASDs with tailored characteristics.

CONCLUSION

PVP-based ASDs could offer significant advantages in the formulation strategies, stability, and performance of poorly soluble drugs to enhance their overall bioavailability. The diverse methodologies and findings presented in this review will pave the way for further advancements in the development of effective and tailored amorphous solid dispersions.

Impact of Processing Methods on the Physico-chemical Properties of Posaconazole Amorphous Solid Dispersions

BACKGROUND & PURPOSE

Different methods have been exploited to generate amorphous solid dispersions (ASDs) of poorly water-soluble drugs. However, the impact of processing methods on drug stability and dissolution hasn't been studied extensively. The purpose of the current study is to investigate the impact of the two common ASD processing methods, hot-melt extrusion (HME) and spray drying, on the chemical/physical stability and supersaturation of Posaconazole (Posa) based ASDs.

METHODS & RESULTS

ASDs with 25% drug loading in hydroxypropylmethylcellulose acetate succinate were prepared using HME, and two types of spray dryers, a Procept Sprayer (ASD-Procept) and a Nano Sprayer (ASD-Nano). The relative physical stability of these ASDs upon exposure to heat and crystalline API seeding followed the order: ASD-Nano > ASD-Procept ≈HME. ASD-Procept and ASD-Nano showed similar chemical stability, slightly less stable than HME under 40°C/75%RH. All three ASDs demonstrated similar supersaturation induction times, and de-supersaturation kinetics with or without crystalline seeds.

CONCLUSIONS

Posa ASDs prepared via spray drying were chemically less stable compared with HME, which can be attributed to their smaller particle size and hollow structure allowing oxygen penetration. For ASD-Procept and HME, the detailed phase changes involving recrystallization of amorphous Posa and a solid-solid phase transition from Posa Form I to Form Ia during the seed-induced studies were proposed. Similar dissolution and supersaturation-precipitation kinetics of three Posa ASDs indicated that any residual nanocrystals in the bulk ASDs were not enough to induce crystallization to differentiate ASDs made by three processing methods.

Navigating the Solution to Drug Formulation Problems at Research and Development Stages by Amorphous Solid Dispersion Technology

Amorphous Solid Dispersions (ASDs) have indeed revolutionized the pharmaceutical industry, particularly in drug solubility enhancement. The amorphous state of a drug, which is a highenergy metastable state, can lead to an increase in the apparent solubility of the drug. This is due to the absence of a long-range molecular order, which results in higher molecular mobility and free volume, and consequently, higher solubility. The success of ASD preparation depends on the selection of appropriate excipients, particularly polymers that play a crucial role in drug solubility and physical stability. However, ASDs face challenges due to their thermodynamic instability or tendency to recrystallize. Measuring the crystallinity of the active pharmaceutical ingredient (API) and drug solubility is a complex process that requires a thorough understanding of drug-polymer miscibility and molecular interactions. Therefore, it is important to monitor drug solids closely during preparation, storage, and application. Techniques such as solid-state nuclear magnetic resonance (ssNMR), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and dielectric spectroscopy have been successful in understanding the mechanism of drug crystallization. In addition, the continuous downstream processing of drug-loaded ASDs has introduced new automated methods for consistent ASD production. Advanced techniques such as hot melt extrusion, KinetiSol, electro spraying, and electrospinning have gained popularity. This review provides a comprehensive overview of Amorphous Solid Dispersions (ASDs) for oral drug delivery. It highlights the critical challenges faced during formulation, the impact of manufacturing variables, theoretical aspects of drug-polymer interaction, and factors related to drug-polymer miscibility. ASDs have been recognized as a promising strategy to improve the oral bioavailability of poorly water-soluble drugs. However, the successful development of an ASD-based drug product is not straightforward due to the complexity of the ASD systems. The formulation and process parameters can significantly influence the performance of the final product. Understanding the interactions between the drug and polymer in ASDs is crucial for predicting their stability and performance.

Bentonite as a water-insoluble amorphous solid dispersion matrix for enhancing oral bioavailability of poorly water-soluble drugs

Bentonite (BT), an orally administrable natural clay, is widely used for medical and pharmaceutical purposes due to its unique properties, including swelling, adsorption and ion-exchange. However, its application as a matrix of amorphous solid dispersion (ASD) formulations is rarely reported, despite the fact that drugs can adsorb to BT in an amorphous state. The objective of this study was to explore the feasibility of BT as a water-insoluble ASD matrix for enhancing the oral bioavailability of poorly water-soluble drugs, including sorafenib (SF). We prepared a novel BT-based ASD of an SF-BT composite (SFBTC) by adsorbing SF onto BT under acidic conditions using the ionic interaction between cationic SF and negatively charged BT. Scanning electron microscopy (SEM), powder X-ray diffractometry (pXRD), and differential scanning calorimetry (DSC) analyses revealed that SF adsorbed to BT in an amorphous state at SF:BT ratios from 1:3 to 1:10. In pharmacokinetic studies in rats, SFBTC (1:3) significantly improved the oral bioavailability of SF, and the AUClast of SFBTC (1:3) was 3.3-fold higher than that of NEXAVAR®, a commercial product of SF. An in vitro release study under sink conditions revealed that SFBTC (1:3) completely released SF in a pH-dependent manner, while a nonsink condition study indicated the generation of supersaturation under intestinal pH conditions. A kinetic solubility study showed that the release of SFBTC (1:3) followed the diffusion-controlled mechanism, which is a typical characteristic of water-insoluble matrix-based ASDs. The pharmacokinetic studies of drug-BT composites of various drugs belonging to BCS class II indicated that the pKa value of the adsorbed drugs is one of the most important factors determining their dissolution and oral bioavailability. These results suggest that BT could be a promising water-insoluble ASD matrix for improving the oral bioavailability of poorly water-soluble drugs, including SF.

Polyelectrolyte-Complex-Based Hydrogel Inserts for Vaginal Delivery of Posaconazole and Probiotics

Worldwide, 40 to 50% of women suffer from reproductive tract infections. Most of these infections are mixed infections, are recurrent and difficult to treat with antimicrobials or antifungals alone. For symptomatic relief of infections, oral antimicrobial therapy must be combined with topical therapy. The purpose of this work is to optimize and develop a polyelectrolyte complex (PEC) of chitosan/anion for the formulation of posaconazole- and probiotic-loaded vaginal hydrogel inserts with prolonged release and significant mucoadhesion. PECs were prepared using chitosan as cationic and carrageenan, pectin and polycarbophil as anionic polymers via a lyophilization technique. PEC formation was confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry, by observing changes in its surface, physical and thermal properties. The probiotic, Lactobacillus casei, was added to the PEC during the lyophilization process and the effect on the probiotic viability was studied. The PECs were further compressed along with posaconazole to form hydrogel inserts and optimized using a 32 full-factorial design. The hydrogel inserts were assessed for swelling behavior, drug release, in vitro mucoadhesion and in vitro antifungal activity. The chitosan-pectin hydrogel insert demonstrated excellent mucoadhesion (1.25 N), sustained drug release (88.2 ± 2.4% in 8 h) and a swelling index of 154.7%. The efficacy of hydrogel inserts was evaluated using in vitro study with a co-culture of Lactobacillus casei and Candida albicans. This study revealed an increase in Lactobacilli casei count and a significant drop in the viable count of Candida albicans (4-log reduction in 24 h), indicating the effectiveness of hydrogel inserts in alleviating the fungal infection. Overall, our study demonstrated the potential of the hydrogel insert for preventing vaginal infection and restoring normal vaginal microbiota.

Amorphous solid dispersions in high-swelling, low-substituted hydroxypropyl cellulose for enhancing the delivery of poorly soluble drugs

Amorphous solid dispersions (ASDs) based on water-insoluble hydrophilic polymers can sustain supersaturation in their kinetic solubility profiles (KSPs) compared to soluble carriers. However, in the limit of very high swelling capacity, the achievable extent of drug supersaturation has not been fully examined. This study explores the limiting supersaturation behavior of ASDs of poorly soluble indomethacin (IND) and posaconazole (PCZ) based on a high-swelling excipient, low-substituted hydroxypropyl cellulose (L-HPC). Using IND as a reference, we showed that the rapid initial supersaturation buildup in the KSP of IND ASD can be simulated through sequential IND infusion steps, however at large times the KSP of IND release from ASD appears more sustained than direct IND infusion. This has been attributed to potential trapping of seed crystals generated in the L-HPC gel matrix thus limiting their growth and rate of desupersaturation. Similar result is also expected in PCZ ASD. Furthermore, the current drug loading process for ASD preparation resulted in the agglomeration of L-HPC based ASD particles, producing granules of up to 300-500µm (cf. 20µm individual particle), with distinct kinetic solubility profiles. This feature makes L-HPC particularly suitable as ASD carriers for fine tuning of supersaturation to achieve enhanced bioavailability for poorly soluble drugs.

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.

Continuous Manufacturing and Molecular Modeling of Pharmaceutical Amorphous Solid Dispersions

Amorphous solid dispersions enhance solubility and oral bioavailability of poorly water-soluble drugs. The escalating number of drugs with poor aqueous solubility, poor dissolution, and poor oral bioavailability is an unresolved problem that requires adequate interventions. This review article highlights recent solubility and bioavailability enhancement advances using amorphous solid dispersions (ASDs). The review also highlights the mechanism of enhanced dissolution and the challenges faced by ASD-based products, such as stability and scale-up. The role of process analytical technology (PAT) supporting continuous manufacturing is highlighted. Accurately predicting interactions between the drug and polymeric carrier requires long experimental screening methods, and this is a space where computational tools hold significant potential. Recent advancements in data science, computational tools, and easy access to high-end computation power are set to accelerate ASD-based research. Hence, particular emphasis has been given to molecular modeling techniques that can address some of the unsolved questions related to ASDs. With the advancement in PAT tools and artificial intelligence, there is an increasing interest in the continuous manufacturing of pharmaceuticals. ASDs are a suitable option for continuous manufacturing, as production of a drug product from an ASD by direct compression is a reality, where the addition of multiple excipients is easy to avoid. Significant attention is necessary for ongoing clinical studies based on ASDs, which is paving the way for the approval of many new ASDs and their introduction into the market.

Dissolution Behavior of Weakly Basic Pharmaceuticals from Amorphous Dispersions Stabilized by a Poly(dimethylaminoethyl Methacrylate) Copolymer

Amorphous solid dispersions (ASDs) are a well-documented formulation approach to improve the rate and extent of dissolution for hydrophobic pharmaceuticals. However, weakly basic compounds can complicate standard approaches to ASDs due to pH-dependent solubility, resulting in uncontrolled drug release in gastric conditions and unstabilized supersaturated solutions prone to precipitation at neutral pH. This work examines the release mechanisms of amorphous dispersions containing model weakly basic pharmaceuticals posaconazole and lumefantrine from a basic poly(dimethylaminoethyl methacrylate) copolymer (Eudragit EPO) and compares their dissolution behavior with ASDs stabilized by acidic and neutral polymers to understand potential benefits to release from a basic polymeric stabilizer. It was found that dissolution of Eudragit EPO ASDs resulted in supersaturation under gastric conditions, which could be sustained upon adjustment to neutral pH. However, the dissolution behavior of Eudragit EPO ASDs was sensitive to the initial pH of the gastric media. For lumefantrine, elevated initial gastric pH resulted in precipitation of amorphous nanoparticles; for posaconazole, elevated gastric pH led to crystallization of the pharmaceutical from solution. This sensitivity to gastric pH was found to originate from the impact of Eudragit EPO on gastric pH and the solubility of each pharmaceutical in the first stage of dissolution. In total, these data illustrate benefits and liabilities for the use of Eudragit EPO for ASDs containing weak pharmaceutical bases to guide the design of robust pharmaceutical formulations.

Hydroxypropyl methylcellulose acetate succinate as an exceptional polymer for amorphous solid dispersion formulations: A review from bench to clinic

Amorphous solid dispersions (ASDs) are a proven system for achieving a supersaturated state of drug, in which the concentration of drug is greater than its crystalline solubility. The usage of Hydroxypropyl Methylcellulose Acetate Succinate (HPMCAS) in the development of ASDs has grown significantly, as evidenced by the fact that majority of commercially approved ASD formulations are based on HPMCAS. HPMCAS has been widely utilized as a solubility enhancer and precipitation inhibitor or stabilizer to achieve supersaturation and inhibit crystallization of drugs in the gastrointestinal tract. The characteristics of HPMCAS ASDs such as less hygroscopic, strong drug-polymer hydrophobic interactions, high solubilization efficiency, greater potential to generate, maintain drug supersaturation and crystallization inhibition outperform other polymeric carriers in ASD development. Furthermore, combining HPMCAS with other polymers or surfactants as ternary ASDs could be a viable approach for enhancing oral absorption of poorly soluble drugs. This review discusses the concepts of supersaturation maintenance or precipitation inhibition of HPMCAS in the ASD formulations. In addition, the mechanisms underlying for improved dissolution performance, oral bioavailability and stability of HPMCAS ASDs are explored.

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.

Optimizing Solvent Selection and Processing Conditions to Generate High Bulk-Density, Co-Precipitated Amorphous Dispersions of Posaconazole

Co-precipitation is an emerging method to generate amorphous solid dispersions (ASDs), notable for its ability to enable the production of ASDs containing pharmaceuticals with thermal instability and limited solubility. As is true for spray drying and other unit operations to generate amorphous materials, changes in processing conditions during co-precipitation, such as solvent selection, can have a significant impact on the molecular and bulk powder properties of co-precipitated amorphous dispersions (cPAD). Using posaconazole as a model API, this work investigates how solvent selection can be leveraged to mitigate crystallization and maximize bulk density for precipitated amorphous dispersions. A precipitation process is developed to generate high-bulk-density amorphous dispersions. Insights from this system provide a mechanistic rationale to control the solid-state and bulk powder properties of amorphous dispersions.

Integrated in silico formulation design of self-emulsifying drug delivery systems

The drug formulation design of self-emulsifying drug delivery systems (SEDDS) often requires numerous experiments, which are time- and money-consuming. This research aimed to rationally design the SEDDS formulation by the integrated computational and experimental approaches. 4495 SEDDS formulation datasets were collected to predict the pseudo-ternary phase diagram by the machine learning methods. Random forest (RF) showed the best prediction performance with 91.3% for accuracy, 92.0% for sensitivity and 90.7% for specificity in 5-fold cross-validation. The pseudo-ternary phase diagrams of meloxicam SEDDS were experimentally developed to validate the RF prediction model and achieved an excellent prediction accuracy (89.51%). The central composite design (CCD) was used to screen the best ratio of oil-surfactant-cosurfactant. Finally, molecular dynamic (MD) simulation was used to investigate the molecular interaction between excipients and drugs, which revealed the diffusion behavior in water and the role of cosurfactants. In conclusion, this research combined machine learning, central composite design, molecular modeling and experimental approaches for rational SEDDS formulation design. The integrated computer methodology can decrease traditional drug formulation design works and bring new ideas for future drug formulation design.

Therapeutic Applications of Solid Dispersions for Drugs and New Molecules: In Vitro and In Vivo Activities

This review aims to provide an overview of studies that address the use, in therapeutic applications, of solid dispersions (SDs) with biological activities in vitro and/or in vivo mainly made up of polymeric matrices, as well as to evaluate the bioactive activity of their constituents. This bibliographic survey shows that the development of solid dispersions provides benefits in the physicochemical properties of bioactive compounds, which lead to an increase in their biological potential. However, despite the reports found on solid dispersions, there is still a need for biological assay-based studies, mainly in vivo, to assist in the investigation and to devise new applications. Therefore, studies based on such an approach are of great importance to enhance and extend the use of solid dispersions in the most diverse therapeutic applications.

Manipulation of Pharmaceutical Polymorphic Transformation Process Using Excipients

BACKGROUND

In the pharmaceutical field, it is vital to ensure a consistent product containing a single solid-state form of the active pharmaceutical ingredient (API) in the drug product. However, some APIs are suffering from the risk of transformation of their target forms during processing, formulation and storage.

METHODS

The purpose of this review is to summarize the relevant category of excipients and demonstrate the availability and importance of using excipients as a key strategy to manipulate pharmaceutical polymorphic transformation.

RESULTS

The excipient effects on solvent-mediated phase transformations, solid-state transitions and amorphous crystallization are significant. Common pharmaceutical excipients including amino acids and derivatives, surfactants, and various polymers and their different manipulation effects were summarized and discussed.

CONCLUSION

Appropriate use of excipients plays a role in manipulating polymorphic transformation process of corresponding APIs, with a promising application of guaranteeing the stability and effectiveness of drug dosage forms.

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.

Mechanism and Improved Dissolution of Glycyrrhetinic Acid Solid Dispersion by Alkalizers

The purpose of this study was to increase the dissolution of glycyrrhetinic acid (GA) by preparing ternary solid dispersion (TSD) systems containing alkalizers, and to explore the modulating mechanism of alkalizers in solid dispersion systems. GA TSDs were prepared by hot melt extrusion (HME) with Kollidon^® VA64 as the carrier and L-arginine/meglumine as the alkalizers. The in vitro release of the TSD was investigated with a dissolution test, and the dissociation constant (pKa) was used to describe the ionization degree of the drug in different pH buffers. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and a molecular model were used for solid-state characterizations and to study the dissolution mechanism of the TSDs. It was evident that the dissolution of GA significantly increased as a result of the TSD compared to the pure drug and binary solid dispersion. SEM, DSC, and XPRD data showed that GA transformed into an amorphous form in TSD. As illustrated by FTIR, Raman, XPS, and molecular docking, high binding energy ion-pair complexes formed between GA and the alkalizers during the process of HME. These can destroy the H-bond between GA molecules. Further, intermolecular H-bonds formed between the alkalizers and Kollidon^® VA64, which can increase the wettability of the drug. Our results will significantly improve the solubility and dissolution of GA. In addition, the lower pKa value of TSD indicates that higher ionization is beneficial to the dissolution of the drug. This study should facilitate further developments of TSDs containing alkalizers to improve the dissolution of weakly acidic drugs and gain a richer understanding of the mechanism of dissolution.

Molecular packing of pharmaceuticals analyzed with paramagnetic relaxation enhancement and ultrafast magic angle pinning NMR

Probing molecular details of fluorinated pharmaceutical compounds at a faster acquisition utilizing paramagnetic relaxation enhancement and better resolution from ultrafast magic angle spinning (ν_rot = 110 kHz) and high magnetic field (B₀ = 18.8 T).

Improvements in sticking, hygroscopicity, and compactibility of effervescent systems by fluid-bed coating

Recently, effervescent tablets (ETs) have become increasingly popular with patients in clinics due to their fast disintegration by acid–alkali reactions in water. However, certain undesirable properties of ETs (e.g., sticking and high hygroscopicity) can limit their production and application. In particular, frequent sticking always severely decreases the tablet quality and productivity. Therefore, in this study, polyvinylpyrrolidone (PVP) at different usage levels, grades, or spray solution concentrations was coated onto the surfaces of both acidic and alkaline granules of ETs by means of the fluid-bed coating technique. In terms of fully characterized powder, tableting, and tablet properties, the following points were concluded: (i) a uniform coating of PVP onto the surfaces of these two granules not only resolved the sticking problem, but also effectively decreased the hygroscopicity and enhanced the compactibility; (ii) the improvements increased with an increase in the PVP content or PVP molecular weight and a decrease in the PVP spray solution concentration owing to the formation of an increasingly even and cohesive coating layer; (iii) the process of fluid-bed coating was not the simple superposition or simple mixing of two different materials' properties; (iv) the coating process did not cause significant influences on the disintegration time of ETs. Overall, it is fairly meaningful to further promote the development of ETs in practice since these problems have been overcome.

Recently, effervescent tablets (ETs) have become increasingly popular with patients in clinics due to their fast disintegration by acid–alkali reactions in water.