Soluplus®: The First Polymeric Solubilizer and Matrix-Forming Polymer with Regulatory Recognition and Unique Advantages for Drug Development.

Formulation of poorly soluble APIs remains one of the most persistent challenges in modern pharmaceutical development. With a growing number of drug candidates falling into Biopharmaceutics Classification System (BCS) Class II and IV, solubility limitations often result in limited bioavailability, further reducing the likelihood of achieving therapeutic efficacy. As a result, formulation scientists continue to seek excipients that can not only improve solubility but also support robust and manufacturable drug delivery strategies.

Soluplus^®, the first polymeric solubilizer and matrix forming polymer, was designed with modern drug development in mind. Offering a unique balance of functionality that supports innovation and practicality, this excipient supports solubility-limited APIs, enables a range of formulation approaches such as hot melt extrusion and spray drying, offers processing flexibility, and is backed by robust quality and regulatory foundations.

Regulatory milestones support development and accelerate progress

As a result of achieving recent regulatory milestones, Soluplus^® is no longer considered a novel excipient in Europe and China. The excipient is officially listed in the European Pharmacopoeia under the monograph title Macrogol poly(vinyl acetate)-poly(vinylcaprolactam) grafted copolymer, marking a significant step forward in global standardization and acceptance. Furthermore, Soluplus^® has been activated in the China DMF system following approval by the National Medical Products Administration (NMPA) as part of a bundling review with a finished drug — opening new doors for developers operating in or entering the Chinese market.

For formulation teams, this regulatory recognition adds an important practical dimension in the consideration of Soluplus^® as an established excipient to support formulation challenges.

A strong fit for amorphous solid dispersion development

One of the most notable application areas for Soluplus^® is the development of amorphous solid dispersions (ASDs). ASDs are widely used to improve the solubility of poorly soluble APIs by dispersing the drug in an amorphous form within a polymeric carrier. The approach can be highly effective, but success depends on the ability of the polymer to support drug dispersion, inhibit recrystallization, and help maintain supersaturation after dissolution.

As an amphiphilic polymeric solubilizer, Soluplus^® can support both molecular-level dispersion of the API and stabilization of the dissolved state. It can therefore contribute to formulation strategies aimed at improving API solubilization while reducing the risk of recrystallization. At the same time, excipient performance remains API-specific and should be confirmed through solid-state characterization, dissolution testing, physical stability studies, and processability assessment.

Processing flexibility: hot-melt extrusion and spray drying

One key advantage of Soluplus^® is its utility across two major ASD manufacturing processes: hot-melt extrusion (HME) and spray drying. This property of processing flexibility allows formulators to accommodate different development and manufacturing methods.

In hot-melt extrusion, polymer selection depends on thermal behavior, melt processability, and the ability to generate homogeneous dispersions without compromising API stability. Designed specifically with HME in mind, Soluplus’ thermal stability and favorable processing profile make it an ideal candidate for this type of manufacturing process. Due to its excellent extrudability at moderate temperatures, strong API-polymer interactions for improved dispersion uniformity, and reliable performance backed by supporting technical data, Soluplus has consistently demonstrated its compatibility with HME.

In spray drying, formulation performance depends on solvent compatibility, feed properties, particle formation, and the resulting solid-state behavior. Soluble in a range of common pharmaceutical solvents, Soluplus^® is applicable as a polymer for spray-dried ASD formulations.

Why formulators should consider Soluplus^®

Digital formulation support with ZoomLab^®

Digital tools can support formulation decisions before resource-intensive lab work begins. ZoomLab^®, BASF’s digital formulation platform, helps to evaluate solubilization strategies, excipient suitability, and ASD feasibility for poorly soluble APIs. For ASD development, predictive apps support early assessment of polymer-API miscibility, solvent selection, and formulation hypotheses. These approaches do not replace experimental studies, but they can help prioritize technically plausible options and make early development more efficient.

Conclusion

Soluplus^® is a unique excipient for addressing poorly soluble APIs, especially where amorphous solid dispersions are under consideration. As an amphiphilic graft copolymer, this excipient offers applicability in hot-melt extrusion and spray drying, and supports formulators with drug solubilization formulation challenges. With regulatory recognition adding to its practical value, and digital tools such as ZoomLab^® supporting smarter pre-screening, Soluplus^® can be positioned as part of a more efficient and development-oriented formulation strategy.

Next steps

Request a sample of Soluplus^® and explore ZoomLab^® to support excipient selection, formulation screening, and ASD development planning.

Source: BASF, website basf.com

If you have any questions or need a sample of a product by BASF, please feel free to contact us at any time: