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Updated: Jan 15, 2026

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Development, Characterization, and Evaluation of CAGE-based Ionic Liquid Systems for Transdermal Delivery
Published on: September 26, 2025
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Ultra-high concentration low-viscosity subcutaneous antibody formulations using ionic liquids.
Anujan Ramesh1, Metecan Erdi1, Shuyang Zhang1
1Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Allston, MA 02134, USA.
Summary
Ionic liquids enable ultra-high concentration monoclonal antibody (mAb) formulations exceeding 200 mg/ml. These novel subcutaneous formulations offer improved stability and bioavailability, addressing an unmet need in therapeutic delivery.
Area of Science:
- Biotechnology
- Pharmaceutical Sciences
- Materials Science
Background:
- Monoclonal antibodies (mAbs) are a major class of therapeutics for oncology, immunology, and neurology.
- Current subcutaneous mAb formulations face limitations due to protein-protein interactions, restricting concentrations to ~150 mg/ml.
- Developing high-concentration, low-viscosity, and stable subcutaneous mAb formulations is a critical unmet need.
Purpose of the Study:
- To investigate the use of ionic liquids (ILs) for formulating monoclonal antibodies at ultra-high concentrations.
- To assess the impact of ILs on antibody stability, viscosity, and bioavailability for subcutaneous administration.
Main Methods:
- Formulation of monoclonal antibodies (IgG) using specific ionic liquids (ILs).
- Characterization of IgG-IL formulations for concentration, viscosity, and stability at various temperatures.
- Evaluation of subcutaneous bioavailability of IgG-IL formulations compared to saline.
Main Results:
- Ionic liquids enabled the formulation of antibodies at concentrations exceeding 200 mg/ml.
- IgG-IL formulations maintained viscosity below the injectable threshold (<20 cP).
- Formulations demonstrated stability at room temperature and 37°C, with improved subcutaneous bioavailability.
Conclusions:
- Ionic liquids are effective in mitigating protein-protein interactions for ultra-high concentration mAb formulations.
- IL-based formulations offer a promising approach for stable, low-viscosity subcutaneous delivery of therapeutic antibodies.
- This technology addresses key challenges in mAb formulation, potentially enhancing therapeutic efficacy and patient convenience.

