转载自企业官方网站。作者及内容来源：Crystal Pharmatech.
Crystal Pharmatech技术文章：什么是无定形固体分散体？ 开发优势、应用与使用时机。 本文保留原始技术观点、参考资料和来源链接；全文按英文原文转载。
中文导读与摘要；下方正文为英文原文，并非完整中文译文。
本文为Crystal Pharmatech发布的英文技术文章，以下按英文原文转载，尚未提供中文全文翻译。原始日期为2026-04-28。
Originally published by Crystal Pharmatech. Republished with company attribution. Original technical perspectives, references and source links are retained.
Poor aqueous solubility is one of the leading causes of failure in oral drug development. In fact, ~40% of marketed drugs and up to 70–90% of pipeline compounds exhibit poor water solubility, making dissolution the rate-limiting step for absorption¹.
Amorphous Solid Dispersion (ASD) has emerged as one of the most effective formulation strategies to overcome this challenge—enabling faster dissolution, improved bioavailability, and successful clinical progression.
As drug molecules become increasingly complex, ASD is no longer just a formulation option—it is a critical developability strategy.
ASD is a formulation approach in which drug molecules are molecularly dispersed within a polymer matrix in a non-crystalline (amorphous) state. Unlike crystalline materials, where molecules are arranged in a highly ordered lattice, amorphous systems exist in a higher-energy, disordered structure. This eliminates the crystal lattice barrier and allows the drug to dissolve more rapidly and reach higher apparent solubility².
ASD directly addresses one of the most persistent challenges in pharmaceutical development:
By removing the lattice energy barrier and enabling supersaturation, ASD allows poorly soluble compounds to achieve sufficient exposure for therapeutic effect.
From Crystalline to Amorphous
In crystalline APIs, molecules are tightly packed in a repeating lattice. Before dissolution can occur, the system must overcome this lattice energy. ASD bypasses this step by stabilizing the drug in an amorphous state, where no lattice exists - resulting in:
The Role of Polymer Carriers
Polymers are essential to ASD performance and stability. They serve multiple functions:
Common polymers include HPMC-AS, PVP/VA, Soluplus®, HPMC, Eudragit®, etc., each selected based on API compatibility and formulation goals.
Spray Drying (SD)
Spray drying involves atomizing a drug-polymer-excipient solution into a heated chamber, where rapid solvent evaporation traps the API in its amorphous form within the polymer matrix.
Key advantages:
Hot-Melt Extrusion (HME)
HME processes drug-polymer blends under heat and mechanical shear, forming a homogeneous amorphous dispersion (e.g., glass) without solvents.
Key advantages:
ASD as a Widely Adopted Industry Strategy
ASD has become one of the most widely used enabling technologies in modern drug development, with numerous commercial products successfully utilizing ASD-based formulations³.
This broad adoption reflects its effectiveness in addressing solubility-driven bioavailability challenges. ASD is particularly effective under the following conditions:
| Compound Profile | Why ASD Works |
| BCS Class II | Dissolution is the rate-limiting step, or solubility is critical for bioavailability |
| BCS Class IV | Improves solubility (can combine with permeability strategies) |
| Poorly soluble crystalline APIs | Eliminates lattice energy barrier |
| High molecular weight compounds (e.g., PROTACs) | Enhances dissolution and exposure |
| Early-stage candidates with poor solubility | Enables rapid feasibility and PK evaluation, e.g., using spray drying dispersion (SDD) as suspension for animal dosing |
When Should You NOT Use ASD?
While powerful, ASD is not universally applicable. ASD may not be ideal when:
Early developability assessment is critical to selecting the right strategy.
1. Polymer SelectionThe most critical decision in ASD development. Polymer choice determines stability, drug loading capacity, and dissolution performance.
2. Drug LoadingHigher drug loading increases the risk of phase separation or recrystallization. Optimal loading must balance performance and stability and is determined by drug-polymer compatibility.
3. Physical StabilityASD systems are kinetically stable but thermodynamically metastable and require careful evaluation using:
*4. In Vitro Performance*Dissolution testing in biorelevant media (SGF, FaSSIF, FeSSIF) ensures:
| Aspect | ASD | Crystalline Formulation |
| Solubility | High (amorphous) | Limited |
| Dissolution rate | Fast (supersaturation, wetting) | Slow |
| Stability | Requires polymer | Intrinsically stable |
| Manufacturing | Spray drying / HME | Conventional processes |
| Development speed | Need more time | Fast |
| Complexity | High | Lower |
Successful ASD development requires more than selecting a formulation—it demands a deep integration of solid-state science, formulation strategy, and scalable manufacturing. At Crystal Pharmatech, ASD development is embedded within a Mol2Med™ “first-time-right” framework, enabling seamless progression from early feasibility to clinical manufacturing.
Integrated ASD Development Workflow
Our end-to-end approach connects:
ASD Development Timeline: What to Expect
Compared to conventional formulation approaches (~6 months), ASD formulation packages typically require ~7.5 months, reflecting additional ASD formulation screening and optimization work. However, this modest upfront investment significantly reduces downstream risk and improves the likelihood of clinical success.
Advanced Technology Platforms
One-Stop Mol2Med™ Advantage
This integrated approach enables:
With a proven track record of ~ 80 ASD programs, including 26 GMP-stage projects, Crystal Pharmatech combines scientific expertise with real-world execution experience—ensuring that formulation strategies are not only theoretically sound, but also scalable, manufacturable, and clinically viable.
Amorphous Solid Dispersion has become a cornerstone technology in modern drug development. By enabling oral delivery of poorly soluble compounds, ASD significantly improves the likelihood of clinical success. However, its success depends on sound material science, early evaluation, appropriate polymer selection, and integrated development strategy.