Design of Ternary Amorphous Solid Dispersions for Enhanced Dissolution of Drug Combinations

Clinical implementation of a paediatric 3D-printed combination of Sulfamethoxazole and Trimethoprim

Adherence to treatment is one of the major challenges in chronic diseases. Inappropriate dosage forms or bad taste are the main factor for non-adherence, especially in paediatric patients. 3D printed medicines could be tailored to specific patients to make medicines more acceptable, however the clinical implementation in hospitals is still limited. This study addresses the challenge of developing pharma-inks (mixtures of drugs and excipients) for semi-solid extrusion (SSE) to produce chewable tablets of Sulfamethoxazole (SMX) and Trimethoprim (TMP) for paediatric oncology patients in a hospital setting. SMX and TMP pharma-inks were stable and printable on demand for more than 3 months. The chewable tablets were also stable, and the drug dissolution profiles were comparable to those of the commercial formulations, indicating potential bioequivalence. Human sensory evaluations confirmed that the formulation improved palatability compared to traditional suspensions. 3D-printed SMX/TMP formulations are an alternative to traditional formulations for paediatric patients in hospital settings, enhancing acceptability and adherence while enabling personalized dosing.

A comprehensive overview of the role of intermolecular interactions in amorphous solid dispersions

Many recent studies have indicated that drug-polymer intermolecular interactions are an important aspect of amorphous solid dispersions (ASDs) and determine many of the properties of this type of formulations. In this review, a comprehensive overview is given of the latest insights with respect to intermolecular interactions in ASDs. The thermodynamic properties and theoretical considerations of the interactions are discussed, followed by a detailed and critical overview of the various solid-state analysis techniques used to probe interactions at the disposal of the formulation scientist. As the physical stability and the pharmaceutical performance of the ASD are its most crucial properties, the most recent understanding of the influence of drug-polymer interactions on these aspects is addressed as well. It is clear that intermolecular interactions may provide many advantages for ASDs but need to be weighed against the possible disadvantages. Further investigation into the interplay and trade-off between physical stability and dissolution properties is necessary in order to be able to take full advantage of the possible benefits of the interactions.

Impact of route of particle engineering on dissolution performance of posaconazole

Even when they have similar particle size, micron sized drug crystals prepared via different process routes may still exhibit considerable variability in pharmaceutical properties, due to the anisotropy of molecular crystals. This study aims to evaluate the dissolution performance of micronized posaconazole obtained through both milling and precipitation, with and without polymer coating. To overcome the problem of pressure-induced amorphization of posaconazole, powder dissolution was performed instead of intrinsic dissolution, which requires compressing powder into pellets. However, direct powder dissolution was challenged by the poor dispersibility of micronized posaconazole powders because of their extremely poor wettability. To solve this problem, we pretreated powders by dispersing them in an aqueous solution with a surfactant. Despite posaconazole forming a hydrate after pretreatment, differences in measured powder dissolution rates are meaningful in predicting impact of routes of API engineering on biopharmaceutical performance since hydration of posaconazole also occurs in vivo. This case study presents a systematic approach in addressing challenges when characterizing dissolution performance of drug powders.

Stability of Ternary Drug-Drug-Drug Coamorphous Systems Obtained Through Mechanochemistry

Background/Objectives: This study investigates the preparation of coamorphous systems composed entirely of active pharmaceutical ingredients (APIs), namely praziquantel, niclosamide, and mebendazole. The objective was to formulate and characterize binary and ternary coamorphous systems to evaluate their structural, thermal, and stability properties. Methods: Ten different mixtures (binary and ternary) were designed through a mixture design approach and prepared using a sustainable, one-step neat grinding process in a lab-scale vibrational mill. The systems were prepared reproducibly within 4 h across the entire experimental domain. Structural characterization was performed using PXRD and FTIR to confirm the absence of crystalline domains and the presence of molecular interactions. The glass transition temperature (Tg) was theoretically calculated using the Gordon-Taylor equation for three-component systems and determined experimentally via DSC. Stability studies were conducted on seven systems under different storage conditions (-30 °C, 5 °C, 25 °C, and 40 °C) for six months. Results: PXRD analysis confirmed the formation of coamorphous systems with no crystalline phases. DSC revealed a single Tg for most systems, indicating homogeneity. Stability studies demonstrated that five out of seven systems adhered to the "Tg-50 °C" stability rule, remaining physically stable over six months. Recrystallization studies indicated diverse pathways: some systems reverted to their original crystalline phases, while others formed new entities such as cocrystals. Conclusions: This study highlights the feasibility of coamorphous systems composed of multiple APIs using a simple, solvent-free grinding approach. The findings underscore the importance of molecular interactions in determining stability and recrystallization behavior, offering insights for designing robust coamorphous formulations.

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.

Investigation of the dissolution rate and oral bioavailability of atenolol-irbesartan co-amorphous systems

Irbesartan (IBS), a common drug to treat hypertension, has poor oral bioavailability because of its limited aqueous solubility. Recently, co-amorphous systems (CAMs) have demonstrated the ability to improve the solubility of poorly water-soluble drugs. In this study, IBS was co-amorphized with a pharmacologically relevant drug atenolol (ATL) by melt-quenching. The structures of the resulting ATL-IBS CAMs, which were formulated in molar ratios of 2:1, 1:1, 1:2 and 1:4, were characterized by the polarizing microscopy, powder X-ray diffraction, differential scanning calorimetry, and Fourier-infrared transform spectroscopy. ATL-IBS CAM1:1 showed higher IBS dissolution than crystalline IBS, amorphous IBS (IBS AM) and the other CAMs. The results of the supersaturated solution stability showed that ATL enhanced the supersaturation maintenance of IBS by extensive interactions. The CAMs exhibited excellent physical stability at 25°C/60% RH. The pharmacokinetics experiments showed that the relative oral bioavailability of IBS was 2.78-fold higher than bulk IBS (p < 0.001) after oral administration of ATL-IBS CAM1:1 to rats. The results of this study demonstrate that CAMs provide an alternative option for the development of fixed dose combination of ATL and IBS.

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.

Molecular complexes of drug combinations: A review of cocrystals, salts, coamorphous systems and amorphous solid dispersions

As the advancements in the medical technology and healthcare develop through the years, combinational therapy has evolved to be an important treatment modality in many disease settings, including cancer, cardiovascular disease and infectious diseases. In an effort to alleviate "pill burden" and improve patient compliance, fixed dose combinations (FDCs) have been developed to be used as effective therapeutics. Among all FDCs, the category of drug-drug molecular complexes has been proven an efficient methodology in designing and treating diseases, with many drugs being approved. Among all drug-drug molecular complexes, drug-drug cocrystals, salts, coamorphous systems and solid dispersions have been successfully developed and many have been approved by the FDA. In this review, we dwell deeply into the molecular mechanisms behind the different types of drug-drug molecular complexes, including the key functional groups involved in the intermolecular interactions, the applications of each category of molecular complexes, as well as the advantages and challenges thereof. This comprehensive review provides useful insights into the practical design and manufacture of drug-drug molecular complexes and points out the future direction for the development of new advantageous combinational therapies that benefit more patients.

Effects of Additives on the Physical Stability and Dissolution of Polymeric Amorphous Solid Dispersions: a Review

Polymeric amorphous solid dispersion (ASD) is a popular approach for enhancing the solubility of poorly water-soluble drugs. However, achieving both physical stability and dissolution performance in an ASD prepared with a single polymer can be challenging. Therefore, a secondary excipient can be added. In this paper, we review three classes of additives that can be added internally to ASDs: (i) a second polymer, to form a ternary drug-polymer-polymer ASD, (ii) counterions, to facilitate in situ salt formation, and (iii) surfactants. In an ASD prepared with a combination of polymers, each polymer exerts a unique function, such as a stabilizer in the solid state and a crystallization inhibitor during dissolution. In situ salt formation in ASD usually leads to substantial increases in the glass transition temperature, contributing to improved physical stability. Surfactants can enhance the wettability of ASD particles, thereby promoting rapid drug release. However, their potential adverse effects on physical stability and dissolution, resulting from enhanced molecular mobility and competitive molecular interaction with the polymer, respectively, warrant careful consideration. Finally, we discuss the impact of magnesium stearate and inorganic salts, excipients added externally upon downstream processing, on the solid-state stability as well as the dissolution of ASD tablets.

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

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

Structural Modifications of Polyethylenimine to Control Drug Loading and Release Characteristics of Amorphous Solid Dispersions

Crystalline drugs with low solubility have the potential to benefit from delivery in the amorphous form. The polymers used in amorphous solid dispersions (ASDs) influence their maximum drug loading, solubility, dissolution rate, and physical stability. Herein, the influence of hydrophobicity of crosslinked polyethylenimine (PEI) is investigated for the delivery of the BCS class II nonsteroidal anti-inflammatory drug flufenamic acid (ffa). Several synthetic variables for crosslinking PEI with terephthaloyl chloride were manipulated: solvent, crosslinking density, reactant concentration, solution viscosity, reaction temperature, and molecular weight of the hyperbranched polymer. Benzoyl chloride was employed to cap amine groups to increase the hydrophobicity of the crosslinked materials. Amorphous deprotonated ffa was present in all ASDs; however, the increased hydrophobicity and reduced basicity from benzoyl functionalization led to a combination of amorphous deprotonated ffa and amorphous neutral ffa in the materials at high drug loadings (50 and 60 wt %). All ASDs demonstrated enhanced drug delivery in acidic media compared to crystalline ffa. Physical stability testing showed no evidence of crystallization after 29 weeks under various relative humidity conditions. These findings motivate the broadening of polymer classes employed in ASD formation to include polymers with very high functional group concentrations to enable loadings not readily achieved with existing polymers.

Molecular interactions of niclosamide with hydroxyethyl cellulose in binary and ternary amorphous solid dispersions for synergistic enhancement of water solubility and oral pharmacokinetics in rats

The cellulose-based polymers are extensively employed in oral formulations for addressing ADMET issues of API. Herein, we report the synergistic effect of hydroxyethyl cellulose in solubility/dissolution enhancement of BCS class II, anthelmintic drug niclosamide. The low solubility and poor oral bioavailability are the primary reasons for its high daily dose. The amorphous solid dispersions (ASDs) developed herein demonstrated reproducible solubility and dissolution enhancement in smaller-to-pilot batches. The significant boost in niclosamide solubility in HEC-based binary SD was rationalized as a result of intermolecular H-bonding as indicated by in-silico studies and further supported by characterization data. HEC is plausibly inhibiting the precipitation of drug and thereby enabling high dissolution and permeation across the membrane. The comparative oral pharmacokinetics in Wistar rats at 25 mg/kg provided 4.4-fold higher plasma exposure of niclosamide in SD formulation SB-ASD-N2 over the plain drug. The results presented herein warrant validation of this ASD under clinical settings. Teaser Amorphous solid dispersions of niclosamide.