Recent Advances in Amorphous Solid Dispersions: Preformulation, Formulation Strategies, Technological Advancements and Characterization

Tailoring the release of highly loaded amorphous solid dispersions via additive manufacturing

In the last decades, tremendous improvements have been made in enhancing the bioavailability of poorly soluble active pharmaceutical ingredients (APIs). Lately, their customisation potential has become a reality through filament-based 3D-printing (3DP). Highly loaded oral amorphous solid dispersions (ASDs) are of particular interest, since they drastically reduce the pill burden. However, such systems are limited by their high tendency of API recrystallisation, compromising the API solubility and the mechanical properties of filaments fabricated for 3DP. The following work closes this gap by developing compact 3DP tablets containing an ASD system of 70 % itraconazole in hydroxypropyl methylcellulose acetate succinate (HPMCAS). The processability via HME and 3DP processes was thoroughly investigated by considering filament properties such as solid-state, rheology and mechanical behaviour. Even after six months of storage, the ASD did not show recrystallisation and maintained a zero-order drug release for variable 3DP infill patterns, demonstrating the potential of this approach for on-demand processing at the point-of-care. A strong differentiation in release kinetics was found for different infills that can be used for further improvement of the product to allow tailored release rates. This work provides a strong basis for successful personalisation of highly loaded ASDs via 3DP.

Comparative study of Hot-Melt Extrusion, spray drying, and KinetiSol® processing to formulate a poorly water-soluble and thermolabile drug

Fenbendazole (FBZ), a benzimidazole-carbamate anthelmintic, shows promising chemotherapeutic properties. However, it is a poorly water-soluble molecule, leading to low and variable oral bioavailability. This study investigated hot-melt extrusion (HME), spray drying, and KinetiSol processing (KSD) using Soluplus (SOL) to enhance FBZ's solubility. Formulating FBZ as an amorphous solid dispersion (ASD) by HME at a barrel temperature of 120 °C led to extensive chemical degradation of FBZ, generating the degradation product fenbendazoleamine. On the other hand, spray-drying (SD) generated an ASD, but its usefulness was greatly limited by the low solubility of FBZ in the cosolvent system required in the SD process. Given FBZ's poor solubility in both water and organic solvents and its thermolabile propensity, KSD was explored. Conventional KSD parameters reduced the impurity levels to 6.4 % at a discharge temperature of 64 °C. To further minimize impurity levels, we investigated alternative KSD parameters that terminate the process before reaching the melt agglomeration phase. These conditions resulted in powder-discharged KSD samples (pKSD) that avoided causing chemical degradation of FBZ. The pKSD samples exhibited trace crystallinity, as confirmed by Wide Angle X-ray Scattering (WAXS). Scanning electron microscopy (SEM) revealed that these samples comprised nano- and micron-sized particle aggregates. These results were confirmed by processing FBZ with other excipients, such as semi-crystalline polymers and cyclodextrins. The pKSD samples demonstrated improved dissolution performance of FBZ compared to the physical mixture and crystalline neat FBZ due to the smaller particle size of FBZ. pKSD FBZ provides a solution for formulating thermolabile molecules like FBZ while only requiring a few seconds of exposure to the pKSD manufacturing process conditions, thus eliminating the disadvantages of SD (e.g., requiring sufficiently high solubility in the organic solvent system) and HME (e.g., exposure to high shear and heat during the process).

Exploration of enalapril-lacidipine co-amorphous system with superior dissolution, in vivo absorption and physical stability via incorporated into mesoporous silica

In the present study, enalapril (ENP) was taking as a potential co-former to fabricate co-amorphous system with lacidipine (LCDP). The ENP/LCDP co-amorphous system was firstly prepared with or without mesoporous SiO2 and characterized by DSC, XRD and SEM technologies. The potential molecular interactions were evaluated by FTIR spectrums. Furthermore, the dissolution and pharmacokinetics behavior of various formulations were also carried out. It was demonstrated that the completely co-amorphization was obtained at ENP/LCDP 2:1 molar ratio by the intermolecular interactions between ENP and LCDP. The ENP/LCDP co-amorphous system significantly improve the dissolution rate of LCDP and ENP respectively. Compared to the naked ENP/LCDP co-amorphous system, remarkable enhancement of dissolution rate and bioavailability of model drugs was observed by incorporated the co-amorphous system into mesoporous SiO2, and a superior physical stability was also observed after accelerated study. Raman mapping revealed that the less microstructure phase separation could be the main reason for the better stability in presence of mesoporous SiO2. In conclusion, ENP could be successfully used as a potential co-former to fabricate co-amorphous system with poorly water-soluble drugs and collaborates the co-amorphous with mesoporous SiO2 become a promising strategy to achieve stable amorphous formulation for further enhancement of dissolution rate and bioavailability.

Optimization and assessment of three generation solid dispersion for enhancement of solubility and dissolution for montelukast sodium

OBJECTIVE

To enhance the solubility of Montelukast sodium using three generation polymers by solid dispersion method.

MATERIAL AND METHOD

Montelukast sodium with selected generation of carriers were used for phase solubility and to optimize the stoichiometric ratio for the preparation of SD with MS. Various characterization techniques (FTIR, DSC and XRD) have been used to evaluate the MS-SD formulations with selected hydrophilic carriers. Dissolution and stability study were also investigated.

RESULT AND DISCUSSION

The two best-selected formulations (MS-PVP & MS-HPMC SD) have shown the highest dissolution profile as compared to pure drug, physical mixture and commercially available marketed product (Montel-10, Cipla). The FTIR, DSC and XRD results of these SD formulations have shown interaction between drug and polymers, decrease in enthalpy compared to the drug and amorphous behavior respectively. Finally, MS-PVP & MS-HPMC SD formulations have shown good stability for one-month period under accelerated storage condition.

CONCLUSION

The study showed increase in solubility of Montelukast sodium with second generation polymers (PVP & HPMC) in comparison to pure drug as well as marketed formulation.

Oral dosage forms for drug delivery to the colon: an existing gap between research and commercial applications

Oral drug administration is the preferred route for pharmaceuticals, accounting for ~90% of the global pharmaceutical market due to its convenience and cost-effectiveness. This study provides a comprehensive scientific and technological analysis of the latest advances in oral dosage forms for colon-targeted drug delivery. Utilizing scientific and patent databases, along with a bibliometric analysis and bibliographical review, we compared the oral dosage forms (technology) with the specific application of the technology (colon delivery) using four search equations. Our findings reveal a gap in the publications and inventions associated with oral dosage forms for colon release compared to oral dosage forms for general applications. While tablets and capsules were found the most used dosage forms, other platforms such as nanoparticles, microparticles, and emulsions have been also explored. Enteric coatings are the most frequently applied excipient to prevent the early drug release in the stomach with pH-triggered systems being the predominant release mechanism. In summary, this review provides a comprehensive analysis of the last advancements and high-impact resources in the development of oral dosage forms for colon-targeted drug delivery, providing insights into the technological maturity of these approaches.

Characteristics of Tylvalosin Tartrate Enteric Amorphous Pellets Prepared by Liquid Layering

PURPOSE

Tylvalosin Tartrate (TAT), a new-generation macrolide antibiotic, undergoes significant degradation in the stomach and in vivo rapid elimination upon oral administration, resulting in poor bioavailability. This study developed TAT enteric amorphous pellets by liquid layering (TAT/EAP-LL) with pH-sensitive and burst release characteristics, to enhance drug stability in the stomach and concentration enrichment in the duodenum.

METHODS

The drug loading layer, isolation layer and enteric layer were formed on the surface of the blank core pellets. Investigation into the characteristics of TAT/EAP-LL revealed that stable amorphous solid dispersions in the drug loading layer were formed by liquid layering. Then, DSC analysis confirmed that triethyl citrate significantly improved the film-forming properties of Methacrylic-ethyl acrylate copolymer. Additionally, TAT/EAP-LL was confirmed to exist in the amorphous state by DSC、PXRD and PLM.

RESULTS

In vitro, TAT/EAP-LL demonstrated a similar 4.07% release within 2 h at pH 1.0 as TAT enteric pellets (TAT/EP-LL) and a much faster burst release at pH 6.8, with complete release within 15 min. In vivo, the oral bioavailability of TAT/EAP-LL was improved to 1.71 times compared to commercial formulations and 1.47 times compared to TAT/EP-LL.

CONCLUSION

This study offers a novel platform for the enhanced oral delivery of TAT and proposes effective formulation strategies for pulsatile drug delivery.

Enhancing Process Control and Quality in Amorphous Solid Dispersions Using In-Line UV-Vis Monitoring of L* as a Real-Time Response

Background: This study demonstrates the application of the sequential design of experiments (DoE) approach within the quality by design (QbD) framework to optimize extrusion processes through screening, optimization, and robustness testing. Methods: An in-line UV-Vis process analytical technology (PAT) system was successfully employed to monitor critical quality attributes (CQAs) of piroxicam amorphous solid dispersion (ASD) extrusion products, specifically lightness (L*). Results: L* measurement proved highly effective for ensuring the quality and uniformity of ASDs, offering real-time insights into their physical appearance and process stability. Small variations in L* acted as early indicators of processing issues, such as phase separation or bubble formation, enabling timely intervention. This straightforward and rapid technique supports real-time process monitoring and control, allowing automated adjustments to maintain product consistency and quality. By adopting this strategy, manufacturers can minimize variability, reduce waste, and ensure adherence to quality target product profiles (QTPPs). Conclusions: Overall, this study highlights the value of in-line UV-Vis spectroscopy as a PAT tool in hot melt extrusion, enhancing CQA assessment and advancing the efficiency and reliability of ASD manufacturing.

Solid dispersion of alectinib HCl: preclinical evaluation for improving bioavailability and establishing an IVIVC model

OBJECTIVE

Alectinib HCl (ALB-HCl) is a BCS class IV molecule with low solubility and low oral bioavailability. Owing to its low bioavailability, a high dose of ALB-HCl is recommended with food to meet clinical efficacy. Thus, there is a need for a delivery system to overcome the bioavailability concerns.

METHODS

Three solid dispersion (SD) formulations (I, II, and III) were evaluated for in-vitro dissolution and in-vivo pharmacokinetics (PK) study in Wistar rats. An in-vitro and in-vivo correlation (IVIVC) model was developed to establish a relationship between in-vitro dissolution data and in-vivo PK data. The formulations were subjected to stability studies.

RESULTS

All formulations showed enhanced dissolution in all the media except Formulation I in FaSSIF media. In-vivo PK studies displayed that Formulation I was inferior to API alone. Formulations II and III (amorphous SD [ASD]) exhibited two-fold higher Cmax and AUC0-last than API alone. Level A IVIVC model was established for Cmax and AUC0-last with an acceptable % prediction error (PE). When evaluated for external predictability, the model was found validated for Cmax (% PE <10%), however, it was inconclusive for AUC0-last (%PE -14.03). Stability studies showed ASD formulations were stable during storage.

CONCLUSION

A stable ASD formulation of ALB-HCl was successfully developed with improved bioavailability. Developing an IVIVC model can act as a surrogate to predict in-vivo performance. The selection of formulation components in ASD shall be rationalized for bioavailability and stability before clinical evaluation.

Hydrolysis of cellulose acetate phthalate and hydroxypropyl methylcellulose phthalate in amorphous solid dispersions

The preparation of amorphous solid dispersions (ASDs) represents a promising strategy for addressing the solubility limitations of poorly soluble drugs, facilitating enhanced oral absorption. Acidic polymers such as cellulose acetate phthalate (CAP) and hydroxypropyl methylcellulose phthalate (HPMCP) have emerged as effective carriers for ASDs. Although the hydrolytic degradation of these polymers has been documented, its impact on the stability of ASDs has not been systematically investigated. This research aimed to explore the potential hydrolysis of CAP and HPMCP and how it influences the stability of ASDs containing ketoconazole (KTZ), at drug loadings of 10 % and 50 %. Our study utilized thermal analysis, infrared spectroscopy, and evaluations of physical and chemical stability. The results revealed that although KTZ remained physically stable in all ASDs over 60 days under various stability conditions, the emergence of crystalline phthalic acid (PA), a byproduct of polymer hydrolysis, was observed at elevated temperatures and relative humidity levels. The acidic microenvironment fostered by the release of PA further catalyzed drug chemical degradation. This study underscores the susceptibility of CAP and HPMCP to hydrolytic degradation, highlighting the inherent risk of PA-induced drug degradation, particularly for acid-labile compounds. These insights into the understanding of polymer hydrolysis in ASDs pave the way for the development of targeted approaches to safeguard drug stability and optimize pharmaceutical formulations for enhanced bioavailability, efficacy, and safety.

Mechanistic Insights into Amorphous Solid Dispersions: Bridging Theory and Practice in Drug Delivery

Improving the bioavailability  of poorly water-soluble drugs presents a significant challenge in pharmaceutical development. Amorphous solid dispersions (ASDs) have garnered substantial attention for their capability to augment the solubility and dissolution rate of poorly water-soluble drugs, thereby markedly enhancing their bioavailability. ASDs, characterized by a metastable equilibrium where the active pharmaceutical ingredient (API) is molecularly dispersed, offer enhanced absorption compared to crystalline forms. This review explores recent research advancements in ASD, emphasizing dissolution mechanisms, phase separation phenomena, and the importance of drug loading and congruency limits on ASD performance. Principal occurrences such as liquid-liquid phase separation (LLPS) and supersaturation are discussed, highlighting their impact on drug solubility, absorption and subsequent bioavailability. Additionally, it addresses the role of polymers in controlling supersaturation, stabilizing drug-rich nanodroplets, and inhibiting recrystallization. Recent advancements and emerging technologies offer new avenues for ASD characterization and production and demonstrate the potential of ASDs to enhance bioavailability and reduce variability, making possible for more effective and patient-friendly pharmaceutical formulations. Future research directions are proposed, focusing on advanced computational models for predicting ASD stability, use of novel polymeric carriers, and methods for successful preparations.

Enhancing Patient-Centric Drug Development: Coupling Hot Melt Extrusion with Fused Deposition Modeling and Pressure-Assisted Microsyringe Additive Manufacturing Platforms with Quality by Design

In recent years, with the increasing patient population, the need for complex and patient-centric medications has increased enormously. Traditional manufacturing techniques such as direct blending, high shear granulation, and dry granulation can be used to develop simple solid oral medications. However, it is well known that "one size fits all" is not true for pharmaceutical medicines. Depending on the age, sex, and disease state, each patient might need a different dose, combination of medicines, and drug release pattern from the medications. By employing traditional practices, developing patient-centric medications remains challenging and unaddressed. Over the last few years, much research has been conducted exploring various additive manufacturing techniques for developing on-demand, complex, and patient-centric medications. Among all the techniques, nozzle-based additive manufacturing platforms such as pressure-assisted microsyringe (PAM) and fused deposition modeling (FDM) have been investigated thoroughly to develop various medications. Both nozzle-based techniques involve the application of thermal energy. However, PAM can also be operated under ambient conditions to process semi-solid materials. Nozzle-based techniques can also be paired with the hot melt extrusion (HME) process for establishing a continuous manufacturing platform by employing various in-line process analytical technology (PAT) tools for monitoring critical process parameters (CPPs) and critical material attributes (CMAs) for delivering safe, efficacious, and quality medications to the patient population without compromising critical quality attributes (CQAs). This review covers an in-depth discussion of various critical parameters and their influence on product quality, along with a note on the continuous manufacturing process, quality by design, and future perspectives.

Amorphous Solid Dispersions of Glycyrrhetinic Acid: Using Soluplus, PVP, and PVPVA as the Polymer Matrix to Enhance Solubility, Bioavailability, and Stability

Glycyrrhetinic acid (GA) possesses various pharmacological effects, including anti-inflammatory, anti-tumor, and anti-viral properties. However, its clinical application is limited by poor solubility and low oral bioavailability. Polymers play a crucial role in pharmaceutical formulations, particularly as matrices in excipients to enhance the solubility, bioavailability, and stability of active pharmaceutical ingredients. The amorphous solid dispersions (ASDs) of GA were prepared with three different polymers (i.e., GA-S-ASD, GA-VA64-ASD, and GA-K30-ASD). The ASDs were characterized by differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR spectroscopy), molecular docking, and contact angle measurement. Pharmacokinetics were evaluated in Beagle dogs, and long-term stability was examined. The solubility of GA increased with the rising weight of the polymer, and the optimal drug-to-carrier ratio was 1:5. In all ASDs, GA was amorphous, thus suggesting that a hydrogen bonding must have formed between GA and the polymers. The molecular docking showed that the binding energy was the highest and the hydrogen bonding was the strongest between GA and Soluplus. The dissolution of the ASDs was primarily driven by carrier-controlled dissolution, and there was minor influence from diffusion-limited release in the case of GA-S-ASD. The three ASDs significantly improved the bioavailability of GA. However, only GA-S-ASD passed the accelerated stability test. In the case of GA-VA64-ASD and GA-K30-ASD, due to serious moisture absorption, the originally fluffy ASDs became gels, and recrystallization occurred. Overall, GA-S-ASD presents promising potential for pharmaceutical applications due to its superior solubility, bioavailability, and stability.

Engineering sodium alginate microparticles with different crystallinities for niclosamide repositioning and solubilization to improve solubility and oral bioavailability in rats

Niclosamide is a commonly used anthelmintic; however, its poor aqueous solubility limits its oral bioavailability. Enhancing its solubility and oral bioavailability is crucial for its repositioning as an anticancer agent. Here, we aimed to develop new sodium alginate-poloxamer microparticles with different crystallinities to increase drug solubility and oral bioavailability. Sodium alginate and poloxamer were used as the polymer and surfactant, respectively, to prepare niclosamide-loaded microparticles via spray drying. The optimized amorphous and crystalline microparticles were prepared with niclosamide/sodium alginate/poloxamer weight ratios of 1:2.5:3 and 1:1.125:0.375, respectively. Their solubilities, dissolution rates, physicochemical properties, and oral bioavailabilities were compared with those of drug powder in rats. Physicochemical characterization of the developed particles revealed changed structure from crystalline to amorphous, with no irregular crystalline characteristics but decreased particle size. Compared to the pure drug powder, crystalline microparticles retained their crystalline nature with no significant changes in particle size. Both microparticles showed significantly higher aqueous solubilities, dissolution rates, and oral bioavailabilities than niclosamide powder in rats. Amorphous microparticles showed higher solubility (approximately 1775-fold) and oral bioavailability (approximately 5.6-fold) than niclosamide powder due to the crystalline-to-amorphous change and decreased particle size. The developed amorphous microparticles can be used to improve niclosamide solubility and oral bioavailability.

Fabrication of Engineered Drug-Polymer Composite Particles via Piezoelectric Inkjet Technique for Floating Drug Delivery Systems

This study presents a simple approach for fabricating low-density drug-polymer amorphous solid dispersions (ASDs) using a piezoelectric inkjet method, demonstrating potential applications for floating drug delivery systems (FDDS). By adjusting the ratio of two polymers, polylactic acid, and Eudragit RLPO, the floatability and drug release rate of the drug-polymer ASD particles can be easily manipulated. Kinetic model analyses have been conducted to interpret the drug release mechanism. This work offers a robust platform for exploring diverse polymer-drug combinations that are applicable to FDDS.

Screening of Polymers for Oral Ritonavir Amorphous Solid Dispersions by Film Casting

Background/Objectives: Drug-polymer interactions and miscibility promote the formation and performance of amorphous solid dispersions (ASDs) of poorly soluble drugs for improved oral bioavailability. The objective of this study was to employ drug-polymer interaction calculations and small-scale experimental characterization to screen polymers for potential ASDs of ritonavir. Methods: Seven polymers across four polymer types were screened as follows: an enteric one (EudragitS100), amphiphilic ones (HPMCAS-L, HPMCAS-H, and their 1:1 combination), hydrophilic ones (PEG-6000, PVP-VA), and a surfactant (Soluplus), including PVP-VA as a positive control, as the commercial ASD employs PVP-VA. Drug-polymer interaction calculations were performed for Hansen solubility parameter, Flory-Huggins parameter, and glass transition temperature. ASDs were prepared via film casting. Experimental characterizations included drug solubility in polymer solutions, polymer inhibition of drug precipitation, polarized light microscopy, differential scanning calorimetry, solubilization capacity, and dissolution studies. Results: HPMCAS-L, HPMCAS L:H, and Soluplus, along with the positive control PVP-VA, were identified as polymers for potential ASDs of ritonavir, with HPMCAS-L and PVP-VA being preferable. HPMCAS-L and the positive control PVP-VA were always viable for both 20% and 40% drug loads across all tests. Films with each of these four polymers showed improved dissolution compared to amorphous ritonavir without polymer. Drug-polymer interaction calculations anticipated the unfavorable small-scale experimental results for PEG-6000 and EudragitS100. Conclusion: Overall, the results contribute towards a resource-sparing approach to identify polymers for ASDs.

Dry Amorphization of Itraconazole Using Mesoporous Silica and Twin-Screw Technology

Background/Objectives: Amorphization of an active pharmaceutical ingredient (API) can improve its dissolution and enhance bioavailability. Avoiding solvents for drug amorphization is beneficial due to environmental issues and potential solvent residues in the final product. Methods: Dry amorphization using a twin-screw extruder is presented in this paper. A blend of mesoporous silica particles and crystalline itraconazole was processed using a pharma-grade laboratory scale twin-screw extruder. The influence of different screw configurations and process parameters was tested. Particle size and shape are compared in scanning electron microscopy (SEM) images. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) are used to determine the residual amount of crystalline itraconazole in the final product. Results: An optimized screw configuration for the process was found which leads to more than 90% amorphous API when processed at room temperature. Full amorphization was reached at 70 °C. The specific mechanic energy (SME) introduced into the material during twin-screw processing is crucial for the dry amorphization. The higher the SME, the lower the residual amount of crystalline API. Two months after processing, however, recrystallization was observed by XRD. Conclusions: Dry processing using a twin-screw extruder is continuous, free of solvents and can be performed at low temperatures. This study proves the concept of twin-screw processing with mesoporous silica for dry amorphization of itraconazole.

Self-nanomicellizing solid dispersion: A promising platform for oral drug delivery

Amorphous solid dispersion (ASD) has been widely used to enhance the oral bioavailability of water-insoluble drugs for oral delivery because of its advantages of enhancing solubility and dissolution rate. However, the problems related to drug recrystallization after drug dissolution in media or body fluid have constrained its application. Recently, a self-nanomicellizing solid dispersion (SNMSD) has been developed by incorporating self-micellizing polymers as carriers to settle the problems, markedly improving the ability of supersaturation maintenance and enhancing the oral bioavailability of drug. Spontaneous formation and stability of the self-nanomicelle (SNM) have been proved to be the key to supersaturation maintenance of SNMSD system. This offers a novel research direction for maintaining supersaturation and enhancing the bioavailability of ASDs. To delve into the advantages of SNMSDs, we provide a concise review introducing the formation mechanism, characterization methods and stability of SNMs, emphasizing the advantages of SNMSDs for oral drug delivery facilitated by SNM formation, and discussing relevant research prospects.

The Continuous and Reversible Transformation of the Polymorphs of an MGAT2 Inhibitor (S-309309) from the Anhydrate to the Hydrate in Response to Relative Humidity

Polymorphic control is vital for the quality control of pharmaceutical crystals. Here, we investigated the relationship between the hydrate and anhydrate polymorphs of a monoacylglycerol acyltransferase 2 inhibitor (S-309309). Solvent evaporation and slurry conversion revealed two polymorphs, the hydrate and the solvate. The solvate was transformed into the hydrate by heating. X-ray powder diffraction demonstrated that the hydrate was transformed into an anhydrate via an intermediate state when heated. These crystal forms were confirmed under controlled humidity conditions; the presence of the anhydrate, the intermediate hydrate, or the hydrate depended on the relative humidity at 25 °C. The stoichiometry of S-309309 in water in the hydrate form was 4:1. The hydrates and anhydrates exhibited similar crystal structures and stability. The water of hydration in the intermediate hydrate was 0.1-0.15 mol according to the dynamic vapor sorption profile. The stability and dissolution profile of the anhydrate and hydrate showed no significant change due to similar crystal lattices and quick rehydration of the anhydrate. A mechanism for the reversible crystal transformation between the anhydrate and pseudo-polymorphs of the hydrate was discovered. We concluded that S-309309 causes a pseudo-polymorphic transformation; however, this is not a critical issue for pharmaceutical use.

Preparation and Evaluation of Berberine-Excipient Complexes in Enhancing the Dissolution Rate of Berberine Incorporated into Pellet Formulations

Berberine is used in the treatment of metabolic syndrome and its low solubility and very poor oral bioavailability of berberine was one of the primary hurdles for its market approval. This study aimed to improve the solubility and bioavailability of berberine by preparing pellet formulations containing drug-excipient complex (obtained by solid dispersion). Berberine-excipient solid dispersion complexes were obtained with different ratios by the solvent evaporation method. The maximum saturation solubility test was performed as a key factor for choosing the optimal complex for the drug-excipient. The properties of these complexes were investigated by FTIR, DSC, XRD and dissolution tests. The obtained pellets were evaluated and compared in terms of pelletization efficiency, particle size, mechanical strength, sphericity and drug release profile in simulated media of gastric and intestine. Solid-state analysis showed complex formation between the drug and excipients used in solid dispersion. The optimal berberine-phospholipid complex showed a 2-fold increase and the optimal berberine-gelucire and berberine-citric acid complexes showed more than a 3-fold increase in the solubility of berberine compared to pure berberine powder. The evaluation of pellets from each of the optimal complexes showed that the rate and amount of drug released from all pellet formulations in the simulated gastric medium were significantly lower than in the intestine medium. The results of this study showed that the use of berberine-citric acid or berberine-gelucire complex could be considered a promising technique to increase the saturation solubility and improve the release characteristics of berberine from the pellet formulation.

The baicalein amorphous solid dispersion to enhance the dissolution and bioavailability and effects on growth performance, meat quality, antioxidant capacity and intestinal flora in Taihang chickens

Baicalein (BAI) is a natural flavonoid with antioxidant, antitumor and antibacterial properties. However, the bioavailability of BAI was limited due to low solubility. This study aims to improve the solubility of BAI through the amorphous solid dispersion (ASD) and evaluate changes in its pharmacokinetics and pharmacodynamics in Taihang chickens. Polyethylene caprolactam-polyvinyl acetate-polyethylene glycol grafted copolymer (Soluplus) was chosen as the carrier, and ASD was prepared by rotary evaporation and was characterized by powder X-ray diffractions (PXRD), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FT-IR). In vitro dissolution assays were used to screen the optimal ratio of drug to carrier, in vivo pharmacokinetic assays were conducted to investigate the promoting effect on the absorption. In addition, the effects of ASD on the growth performance, meat quality, antioxidant capacity and intestinal flora were investigated. ASD (1:9 and 2:8) did not exhibit crystal diffraction peaks of BAI in PXRD or endothermic peaks in DSC, indicating the successful preparation of ASD. The results of in vitro dissolution assay showed that the cumulative dissolution rate of ASD (2:8) within 600 min was 52.67%, which was 7.84-fold higher than BAI. The pharmacokinetic results showed that the peak concentration (Cmax) and the area under the drug-time curve (AUC0∼24) of ASD (2:8) was (5.20 ± 0.82) μg/mL and (17.03 ± 0.67) μg·h/mL, which was 1.91 and 2.64-fold higher than BAI, respectively. Dietary supplementation of BAI and ASD could increase average daily gain (ADG), while decrease feed conversion ratio (FCR), but there was no significant difference (P > 0.05). The drip loss of BAIASD group was lower than BAI group (P < 0.05). In addition, the antioxidant capacity of Taihang chickens were enhanced, the diversity and the abundance of beneficial bacteria was improved. Results of BAI upon the dietary supplementation tested in Taihang chickens, after preparation of ASD, indicating a superior enhancement effect in growth performance, meat quality, antioxidant capacity and intestinal flora due to an improved solubility and optimized bioavailability.

Data-Driven Modeling of the Spray Drying Process. Process Monitoring and Prediction of the Particle Size in Pharmaceutical Production

Spray drying is used in the pharmaceutical industry for particle engineering of amorphous solid dispersions (ASDs). The particle size of the spray-dried (SD) powders is one of their key attributes due to its impact on the downstream processes and the drug product's functional properties. Offline and inline laser diffraction methods can be used to estimate the product's particle size; however, the final release of these ASDs is based on offline instruments. This paper presents a novel data-driven modeling approach for predicting the particle size of SD products. The model-based characterization of the process and the product's particle size, as a critical quality attribute, follows the quality by design principles. The resulting model can be used for online process monitoring, reducing the risks of out-of-specifications products and supporting their real-time release. A Tucker3 model is trained to capture and factorize the deterministic variability of the process. Subsequently, a partial least-squares regression model is calibrated to model the impact that variability in the input material properties, the process parameters, and the spray nozzle have on the products' particle size. This strategy has been calibrated and validated using large scale production data for two intermediate drug products under high sparsity of particle size data. Despite the challenges, high accuracy was obtained in predicting the median particle size (dv50) for release. The 99% confidence interval results in an error of maximum 2.5 μm, which is less than 10% of the allowed range of variation.

Amorphous solid dispersion of a binary formulation with felodipine and HPMC for 3D printed floating tablets

This study focuses on the combination of three-dimensional printing (3DP) and amorphous solid dispersion (ASD) technologies for the manufacturing of gastroretentive floating tablets. Employing hot melt extrusion (HME) and fused deposition modeling (FDM), the study investigates the development of drug-loaded filaments and 3D printed (3DP) tablets containing felodipine as model drug and hydroxypropyl methylcellulose (HPMC) as the polymeric carrier. Prior to fabrication, solubility parameter estimation and molecular dynamics simulations were applied to predict drug-polymer interactions, which are crucial for ASD formation. Physical bulk and surface characterization complemented the quality control of both drug-loaded filaments and 3DP tablets. The analysis confirmed a successful amorphous dispersion of felodipine within the polymeric matrix. Furthermore, the low infill percentage and enclosed design of the 3DP tablet allowed for obtaining low-density systems. This structure resulted in buoyancy during the entire drug release process until a complete dissolution of the 3DP tablets (more than 8 h) was attained. The particular design made it possible for a single polymer to achieve a zero-order controlled release of the drug, which is considered the ideal kinetics for a gastroretentive system. Accordingly, this study can be seen as an advancement in ASD formulation for 3DP technology within pharmaceutics.

The challenge of downstream processing of spray dried amorphous solid dispersions into minitablets designed for the paediatric population - A sustainable product development approach

Poorly water-soluble drugs present a significant challenge in the development of oral solid dosage forms (OSDs). In formulation development the appropriate use of excipients to adjust solubility, and the choice of manufacturing method and pharmaceutical processes to obtain a dosage form to meet the needs of the patient group, is crucial. Preparing an amorphous solid dispersion (ASD) is a well-established method for solubility enhancement, and spray drying (SD) a common manufacturing method. However, the poor flowability of spray dried materials poses a significant challenge for downstream processing. Promoting sustainability in OSD development involves embracing a versatile formulation design, which enables a broader spectrum of patients to use the product, as opposed to altering existing dosage forms retrospectively. The objective of the current study was to develop a formulation of spray dried indomethacin ASD suited to the production, by direct compression, of instant release paediatric minitablets. Excipients evaluated were PVP or HPMCAS in solid dispersions at the preformulation phase, and MCC and lactose as a filler in direct compression. From the studied formulations, a 3:1 ratio blend of Vivapur 200/Pharmatose 200 M (MCC/lactose) with 0.5% (w/w) magnesium stearate was found to be the most promising in tableting, and minitablets containing a 6.22% content of spray-dried ASD of indomethacin/PVP K 29-32 could be obtained with desired tablet hardness and pharmaceutical quality, complying with tests of weight variation and fast disintegration in an aqueous environment. As a case example, this study provides a good foundation for further studies in harnessing a sustainable approach to the development of pharmaceutical formulations that can appropriately serve different patient sub-populations.

Early evaluation of opportunities in oral delivery of PROTACs to overcome their molecular challenges

PROteolysis TArgeting Chimeras (PROTACs) offer new opportunities in modern medicine by targeting proteins that are intractable to classic inhibitors. Heterobifunctional in nature, PROTACs are small molecules that offer a unique mechanism of protein degradation by hijacking the ubiquitin-mediated protein degradation pathway, known as the ubiquitin-proteasome system. Herein, we present an analysis on the structural characteristics of this novel chemical modality. Furthermore, we review and discuss the formulation opportunities to overcome the oral delivery challenges of PROTACs in drug discovery.

Drug-drug co-amorphous systems: An emerging formulation strategy for poorly water-soluble drugs

Overcoming the poor water solubility of small-molecule drugs is a major challenge in the development of clinical pharmaceuticals. Amorphization of crystalline drugs is a highly effective strategy to improve their aqueous solubility. However, amorphous drugs are thermodynamically unstable and likely to crystallize during manufacturing and storage. Recently, drug-drug co-amorphous systems have emerged as a novel strategy to not only enable enhanced dissolution and physical stability of the individual drugs within the system but also to provide a strategy for combination therapy of the same or different clinical indications. This review serves to highlight advances in the methods used to manufacture and characterize drug-drug co-amorphous systems, summarize drug-drug co-amorphous applications reported in recent decades, and provide an outlook on future possibilities and perspectives.

In Vitro and Biological Evaluation of Oral Fast-Disintegrating Films Containing Ranitidine HCl and Syloid® 244FP-Based Ternary Solid Dispersion of Flurbiprofen

Flurbiprofen (FBP), a nonsteroidal anti-inflammatory drug (NSAID), is commonly used to treat the pain of rheumatoid arthritis, but in prolonged use it causes gastric irritation and ulcer. To avoid these adverse events of NSAIDs, the simultaneous administration of H2 receptor antagonists such as ranitidine hydrochloride (RHCl) is obligatory. Here, we developed composite oral fast-disintegrating films (ODFs) containing FBP along with RHCl to provide a gastroprotective effect as well as to enhance the solubility and bioavailability of FBP. The ternary solid dispersion (TSD) of FBP was fabricated with Syloid® 244FP and poloxamer® 188 using the solvent evaporation technique. The synthesized FBP-TSD (coded as TSD) was loaded alone (S1) and in combination with plain RHCl (S2) in the composite ODFs based on hydroxypropyl methyl cellulose E5 (HPMC E5). The synthesized composite ODFs were evaluated by in vitro (thickness, folding endurance, tensile strength, disintegration, SEM, FTIR, XRD and release study) and in vivo (analgesic, anti-inflammatory activity, pro-inflammatory cytokines and gastroprotective assay) studies. The in vitro characterization revealed that TSD preserved its integrity and was effectively loaded in S1 and S2 with optimal compatibility. The films were durable and flexible with a disintegration time ≈15 s. The release profile at pH 6.8 showed that the solid dispersion of FBP improved the drug solubility and release when compared with pure FBP. After in vitro studies, it was observed that the analgesic and anti-inflammatory activity of S2 was higher than that of pure FBP and other synthesized formulations (TSD and S1). Similarly, the level of cytokines (TNF-α and IL-6) was also markedly reduced by S2. Furthermore, a gastroprotective assay confirmed that S2 has a higher safety profile in comparison to pure FBP and other synthesized formulations (TSD and S1). Thus, composite ODF (S2) can effectively enhance the FBP solubility and its therapeutic efficacy, along with its gastroprotective effect.

Improvement in Inhalation Properties of Theophylline and Levofloxacin by Co-Amorphization and Enhancement in Its Stability by Addition of Amino Acid as a Third Component

Co-amorphous systems are amorphous formulations stabilized by the miscible dispersion of small molecules. This study aimed to design a stable co-amorphous system for the co-delivery of two drugs to the lungs as an inhaled formulation. Theophylline (THE) and levofloxacin (LEV) were used as model drugs for treating lung infection with inflammation. Leucine (LEU) or tryptophan (TRP) was employed as the third component to improve the inhalation properties. The co-amorphous system containing THE and LEV in an equal molar ratio was successfully prepared via spray drying where reduction of the particle size and change to the spherical morphology were observed. The addition of LEU or TRP at a one-tenth molar ratio to THE-LEV did not affect the formation of the co-amorphous system, but only TRP acted as an antiplasticizer. The Fourier transform infrared spectroscopy spectra revealed intermolecular interactions between THE and LEV in the co-amorphous system that were retained after the addition of LEU or TRP. The co-amorphous THE-LEV system exhibited better in vitro aerodynamic performance than a physical mixture of these compounds and permitted the simultaneous delivery of both drugs in various stages. The co-amorphous THE-LEV system crystallized at 40 °C, and this crystallization was not prevented by LEU. However, THE-LEV-TRP maintained its amorphous state for 1 month. Thus, TRP can act as a third component to improve the physical stability of the co-amorphous THE-LEV system, while maintaining the enhanced aerodynamic properties.

Formulation strategies for the development of high drug-loaded amorphous solid dispersions

Amorphous solid dispersions (ASD) have gained tremendous attention over the past two decades as one of the most promising techniques for enhancing the solubility of poorly water-soluble drugs. However, low drug loading is one of the major challenges of ASD technology that limits its commercialization to only a few drug candidates. Increasing the drug loading increases the risk of recrystallization during storage (solid state) and/or during dissolution (solution state). Various formulation and process-related strategies have been explored that open the possibility of formulating high drug-loaded ASDs without the risk of recrystallization. Here, we review various formulation approaches, such as the use of surfactants, mesoporous silicas, polymer combinations, in situ thermal crosslinking, structural modification of polymeric carriers, and surface nanocoating using minerals. We also discuss the mechanisms by which these approaches inhibit solid state and/or solution state recrystallization.

Probing Molecular Packing of Amorphous Pharmaceutical Solids Using X-ray Atomic Pair Distribution Function and Solid-State NMR

The structural investigation of amorphous pharmaceuticals is of paramount importance in comprehending their physicochemical stability. However, it has remained a relatively underexplored realm primarily due to the limited availability of high-resolution analytical tools. In this study, we utilized the combined power of X-ray pair distribution functions (PDFs) and solid-state nuclear magnetic resonance (ssNMR) techniques to probe the molecular packing of amorphous posaconazole and its amorphous solid dispersion at the molecular level. Leveraging synchrotron X-ray PDF data and employing the empirical potential structure refinement (EPSR) methodology, we unraveled the existence of a rigid conformation and discerned short-range intermolecular C-F contacts within amorphous posaconazole. Encouragingly, our ssNMR 19F-13C distance measurements offered corroborative evidence supporting these findings. Furthermore, employing principal component analysis on the X-ray PDF and ssNMR data sets enabled us to gain invaluable insights into the chemical nature of the intermolecular interactions governing the drug-polymer interplay. These outcomes not only furnish crucial structural insights facilitating the comprehension of the underlying mechanisms governing the physicochemical stability but also underscore the efficacy of synergistically harnessing X-ray PDF and ssNMR techniques, complemented by robust modeling strategies, to achieve a high-resolution exploration of amorphous structures.

Sugars and Polyols of Natural Origin as Carriers for Solubility and Dissolution Enhancement

Crystalline carriers such as dextrose, sucrose, galactose, mannitol, sorbitol, and isomalt have been reported to increase the solubility, and dissolution rates of poorly soluble drugs when employed as carriers in solid dispersions (SDs). However, synthetic polymers dominate the preparation of drugs: excipient SDs have been created in recent years, but these polymer-based SDs exhibit the major drawback of recrystallisation upon storage. Also, the use of high-molecular-weight polymers with increased chain lengths brings forth problems such as increased viscosity and unnecessary bulkiness in the resulting dosage form. An ideal SD carrier should be hydrophilic, non-hygroscopic, have high hydrogen-bonding propensity, have a high glass transition temperature (Tg), and be safe to use. This review discusses sugars and polyols as suitable carriers for SDs, as they possess several ideal characteristics. Recently, the use of low-molecular-weight excipients has gained much interest in developing SDs. However, there are limited options available for safe, low molecular excipients, which opens the door again for sugars and polyols. The major points of this review focus on the successes and failures of employing sugars and polyols in the preparation of SDs in the past, recent advances, and potential future applications for the solubility enhancement of poorly water-soluble drugs.

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

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

A Comparative Assessment of Cocrystal and Amorphous Solid Dispersion Printlets Developed by Hot Melt Extrusion Paired Fused Deposition Modeling for Dissolution Enhancement and Stability of Ibuprofen

The primary focus of the research is to study the role of cocrystal and amorphous solid dispersion approaches for enhancing solubility and preserving the stability of a poorly soluble drug, i.e., ibuprofen (IBP). First, the solvent-assisted grinding approach determined the optimum molar ratio of the drug and the coformer (nicotinamide (NIC)). Later, the polymeric filaments of cocrystals and amorphous solid dispersions were developed using the hot melt extrusion (HME) process, and the printlets were fabricated using the fused deposition modeling (FDM) additive manufacturing process. In addition, the obtained filaments were also milled and compressed into tablets as reference samples. The formation of cocrystals and amorphous solid dispersions was evaluated and confirmed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD) analysis. The drug release profiles of 3D printlets with 50% infill were found to be faster and are in line with the release profiles of compressed tablets. In addition, the 3D-printed cocrystal formulation was stable for 6 months at accelerated conditions. However, the 3D printlets of amorphous solid dispersions and compressed tablets failed to retain stability attributed to the recrystallization of the drug and loss in tablet mechanical properties. This shows the suitability of a cocrystal platform as a novel approach for developing stable formulations of poorly soluble drug substances over amorphous solid dispersions.

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

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

Development and evaluation of febuxostat solid dispersion through screening method

Febuxostat (Febux) is a BCS II drug and has a very low solubility. In order to overcome this shortcoming, the purpose of study is to increase the in vitro dissolution (%) and drug release (%) of Febux by using a screening method. The Febux-SD formulation was prepared by screening solubilizers, pH agents, and carriers using with a solvent evaporation method. The novel Febux SD formulation was successfully developed. The dissolution (%) of Febux of optimal formulation (SD3) was higher than that of Feburic® tab in pH 1.2, distilled water (DW), and pH 6.8 buffer by 6.3-, 2.6-, and 1.1-fold, respectively, at 60 min. The in vitro drug release (%) and permeability (μg/cm2) of SD3 formulation were improved compared to those of Feburic® tab in the pH shifting method and PBS (7.4), respectively. The SD3 formulation was well maintained the stability for 6 months, and that of physicochemical properties were altered. In conclusion, the Febux solubilization study with meglumine was first attempted and successfully performed. Through the improved dissolution (%) of Febux, high bioavailability of SD3 formulation is expected in animal and human studies.

Review of industrially recognized polymers and manufacturing processes for amorphous solid dispersion based formulations

Evolving therapeutic landscape through combinatorial chemistry and high throughput screening have resulted in an increased number of poorly soluble drugs. Drug delivery strategies quickly adapted to convert these drugs into successful therapies. Amorphous solid dispersion (ASD) technology is widely employed as a drug delivery strategy by pharmaceutical industries to overcome the challenges associated with these poorly soluble drugs. The development of ASD formulation requires an understanding of polymers and manufacturing techniques. A review of US FDA-approved ASD-based products revealed that only a limited number of polymers and manufacturing technologies are employed by pharmaceutical industries. This review provides a comprehensive guide for the selection and overview of polymers and manufacturing technologies adopted by pharmaceutical industries for ASD formulation. The various employed polymers with their underlying mechanisms for solution-state and solid-state stability are discussed. ASD manufacturing techniques, primarily implemented by pharmaceutical industries for commercialization, are presented in Quality by Design (QbD) format. An overview of novel excipients and progress in manufacturing technologies are also discussed. This review provides insights to the researchers on the industrially accepted polymers and manufacturing technology for ASD formulation that has translated these challenging drugs into successful therapies.

Molecular Dynamics Simulations of Selected Amorphous Stilbenoids and Their Amorphous Solid Dispersions with Poly(Vinylpyrrolidone)

Amorphous solid dispersions (ASDs) are one of the promising strategies to improve the solubility and dissolution rate of poorly soluble compounds. In this study, Molecular Dynamics simulations were used to investigate the interactions between three selected stilbenoids with important biological activity (resveratrol, pinostilbene and pterostilbene) and poly(vinylpyrrolidone). The analysis of the pair distribution functions and hydrogen bond distributions reveals a significant weakening of the hydrogen bond network of the stilbenoids in ASDs compared to the pure (no polymer) amorphous systems. This is accompanied by an increase in the mobility of the stilbenoid molecules in the ASDs, both in the translational dynamics determined from the molecular mean square displacements, and in the molecular reorientations followed by analysing several torsional distributions.

Veering to a Continuous Platform of Fused Deposition Modeling Based 3D Printing for Pharmaceutical Dosage Forms: Understanding the Effect of Layer Orientation on Formulation Performance

Three-dimensional (3D) printing of pharmaceuticals has been centered around the idea of personalized patient-based 'on-demand' medication. Fused deposition modeling (FDM)-based 3D printing processes provide the capability to create complex geometrical dosage forms. However, the current FDM-based processes are associated with printing lag time and manual interventions. The current study tried to resolve this issue by utilizing the dynamic z-axis to continuously print drug-loaded printlets. Fenofibrate (FNB) was formulated with hydroxypropyl methylcellulose (HPMC AS LG) into an amorphous solid dispersion using the hot-melt extrusion (HME) process. Thermal and solid-state analyses were used to confirm the amorphous state of the drug in both polymeric filaments and printlets. Printlets with a 25, 50, and 75% infill density were printed using the two printing systems, i.e., continuous, and conventional batch FDM printing methods. Differences between the two methods were observed in the breaking force required to break the printlets, and these differences reduced as the infill density went up. The effect on in vitro release was significant at lower infill densities but reduced at higher infill densities. The results obtained from this study can be used to understand the formulation and process control strategies when switching from conventional FDM to the continuous printing of 3D-printed dosage forms.

Amorphization of Ethenzamide and Ethenzamide Cocrystals-A Case Study of Single and Binary Systems Forming Low-Melting Eutectic Phases Loaded on/in Silica Gel

The applicability of different solvent-free approaches leading to the amorphization of active pharmaceutical ingredients (APIs) was tested. Ethenzamide (ET), an analgesic and anti-inflammatory drug, and two ethenzamide cocrystals with glutaric acid (GLU) and ethyl malonic acid (EMA) as coformers were used as pharmaceutical models. Calcinated and thermally untreated silica gel was applied as an amorphous reagent. Three methods were used to prepare the samples: manual physical mixing, melting, and grinding in a ball mill. The ET:GLU and ET:EMA cocrystals forming low-melting eutectic phases were selected as the best candidates for testing amorphization by thermal treatment. The progress and degree of amorphousness were determined using instrumental techniques: solid-state NMR spectroscopy, powder X-ray diffraction, and differential scanning calorimetry. In each case, the API amorphization was complete and the process was irreversible. A comparative analysis of the dissolution profiles showed that the dissolution kinetics for each sample are significantly different. The nature and mechanism of this distinction are discussed.

Real-time in situ X-ray micro-computed tomography study of the effect of impurities on the crystallization of amorphous nifedipine

Controlling the physical stability of noncrystalline active pharmaceutical ingredients remains a major challenge in the development of amorphous formulations such as amorphous solid-dispersion (ASD) formulations. To establish new evaluation and formulation strategies, the spatial distribution of the crystal phase in bulk amorphous nifedipine (NFD) was investigated as a model. The crystallization of amorphous NFD and the effect of a deliberately added impurity were investigated using powder X-ray diffraction (PXRD), differential scanning calorimetry and real-time in situ X-ray micro-computed tomography (X-ray CT). The stability data of amorphous samples, i.e., NFD and a mixture of NFD with an oxidative degradation product of NFD, impurity A (Imp A), at a weight ratio of 90:10, presented as percent amorphous remaining, suggests that Imp A accelerates the bulk crystal growth of NFD. Real-time in situ X-ray CT results showed surface-enhanced crystal growth and cavity formation in solid NFD samples. Moreover, the crystals were heterogeneous in density. These results suggest that Imp A affects the physical stability of the amorphous NFD. X-ray CT equipped with a heating unit can aid in-situ evaluation and assessment of physicochemical properties and physical stability of amorphous samples and formulations.

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

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

Hot Melt Extruded Posaconazole-Based Amorphous Solid Dispersions—The Effect of Different Types of Polymers

Four model polymers, representing (i) amorphous homopolymers (Kollidon K30, K30), (ii) amorphous heteropolymers (Kollidon VA64, KVA), (iii) semi-crystalline homopolymers (Parteck MXP, PXP), and (iv) semi-crystalline heteropolymers (Kollicoat IR, KIR), were examined for their effectiveness in creating posaconazole-based amorphous solid dispersions (ASDs). Posaconazole (POS) is a triazole antifungal drug that has activity against Candida and Aspergillus species, belonging to class II of the biopharmaceutics classification system (BCS). This means that this active pharmaceutical ingredient (API) is characterized by solubility-limited bioavailability. Thus, one of the aims of its formulation as an ASD was to improve its aqueous solubility. Investigations were performed into how polymers affected the following characteristics: melting point depression of the API, miscibility and homogeneity with POS, improvement of the amorphous API’s physical stability, melt viscosity (and associated with it, drug loading), extrudability, API content in the extrudate, long term physical stability of the amorphous POS in the binary drug–polymer system (in the form of the extrudate), solubility, and dissolution rate of hot melt extrusion (HME) systems. The obtained results led us to conclude that the physical stability of the POS-based system increases with the increasing amorphousness of the employed excipient. Copolymers, compared to homopolymers, display greater homogeneity of the investigated composition. However, the enhancement in aqueous solubility was significantly higher after utilizing the homopolymeric, compared to the copolymeric, excipients. Considering all of the investigated parameters, the most effective additive in the formation of a POS-based ASD is an amorphous homopolymer—K30.

Twin Screw Melt Granulation: Alternative Approach for Improving Solubility and Permeability of a Non-steroidal Anti-inflammatory Drug Ibuprofen

The current research is focused on investigating the suitability of the twin screw melt granulation (TSMG) approach for improving the solubility of a non-steroidal anti-inflammatory (NSAIDs) drug (ibuprofen), by developing granules using lipid surfactants. The solubility of the drug within the solid lipid excipients (Gelucire® 48/16 and Gelucire® 50/13) was determined by differential scanning calorimetry (DSC). The formulations were developed for drug and lipid ratios of 1:1.5, 1:3, and 1:4.5 using Neusilin® US2 as a solid adsorbent carrier. The solid-state properties of the drug investigated using differential scanning calorimetry (DSC) have revealed the conversion of the drug to an amorphous form for 1:3 and 1:4.5 ratios of formulations confirmed by powder x-ray diffraction analysis (PXRD). Drug-excipient compatibility and formation of no interactions were characterized using Fourier transform infrared spectroscopy (FTIR). The granules with a 1:3 and 1:4.5 ratios of drug and lipid have improved drug dissolution and permeation, attributing to the formation of micellar emulsions. The stability of formulation with a 1:3 ratio of drug and lipid surfactant was preserved when stored in accelerated conditions. However, the formulation with a 1:4.5 ratio of drug and lipid failed to retain the amorphous state evidenced by the recrystallization of the drug. This shows the suitability of TSMG as a single-step continuous manufacturing process for developing melt granules to improve the solubility of poorly water-soluble drug substances.