Development of Ternary Amorphous Solid Dispersions Manufactured by Hot-Melt Extrusion and Spray-Drying─Comparison of In Vitro and In Vivo Performance

Application of rheology to hot melt extrusion: Theory and practice

Hot melt extrusion (HME) has become a key manufacturing method in the pharmaceutical industry for developing novel drug delivery systems, due to its solvent-free nature, ease of operation, and ability to achieve one-step molding and continuous processing. The rheological properties of drug-polymer systems play a crucial role in determining the processability of formulations and the final product quality. This review systematically summarizes the shear-thinning and viscoelastic properties related to polymer melts, as well as the relevant rheological models. It aims to provide a theoretical basis for selecting excipients in HME formulations through the application of rheology and to guide the design of process parameters. Additionally, the review details the application of rheology in the scale-up and modeling of HME processes, exploring its potential for integration with continuous manufacturing, fused deposition modeling 3D printing, and machine learning, with the expectation of empowering HME drug development and playing a valuable role.

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.

Role of rheology in formulation and process design of hot melt extruded amorphous solid dispersions

Hot melt extrusion (HME) has been widely used as a continuous and highly flexible pharmaceutical manufacturing process for the production of a variety of dosage forms. In particular, HME enables preparation of amorphous solid dispersions (ASDs) which can improve bioavailability of poorly water-soluble drugs. The rheological properties of drug-polymer mixtures can significantly influence the processability of drug formulations via HME and eventually the end-use product properties such as physical stability and drug release. The objective of this review is to provide an overview of various rheological techniques and properties that can be used to evaluate the flow behavior and processability of the drug-polymer mixtures as well as formulation characteristics such as drug-polymer interactions, miscibility/solubility, and plasticization to improve the HME processability. An overview of the thermodynamics and kinetics of ASD processing by HME is also provided, as well as aspects of scale-up and process modeling, highlighting rheological properties on formulation design and process development. Overall, this review provides valuable insights into critical rheological properties which can be used as a predictive tool to optimize the HME processing conditions.

Trends in amorphous solid dispersion drug products approved by the U.S. Food and Drug Administration between 2012 and 2023

Forty-eight (48) drug products (DPs) containing amorphous solid dispersions (ASDs) have been approved by the U.S. Food and Drug Administration in the 12-year period between 2012 and 2023. These DPs comprise 36 unique amorphous drugs. Ten (10) therapeutic categories are represented, with most DPs containing antiviral and antineoplastic agents. The most common ASD polymers are copovidone (49%) and hypromellose acetate succinate (30%), while spray drying (54%) and hot melt extrusion (35%) are the most utilized manufacturing processes to prepare the ASD drug product intermediate (DPI). Tablet dosage forms are the most common, with several capsule products available. Line extensions of several DPs based on flexible oral solids and powders for oral suspension have been approved which provide patient-centric dosing to pediatric and other patient populations. The trends in the use of common excipients and film coating types are discussed. Eighteen (18) DPs are fixed-dose combinations, and some contain a mixture of amorphous and crystalline drugs. The DPs have dose/unit of amorphous drug ranging from <5 mg up to 300 mg, with the majority being ≤100 mg/unit. This review details several aspects of DPI and DP formulation and manufacturing of ASDs, as well as trends related to therapeutic category, dose, and patient-centricity.