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In Vitro Evaluation of Poly(D,L-lactide-co-glycolide) In Situ Gels and Pharmacokinetics Following Subcutaneous
Sandy Van Hemelryck1, Charlotte Vercammen1,2, Eline Seldeslachts1,2
1Clinical Pharmacology and Pharmacometrics, Johnson & Johnson, Turnhoutseweg 30, 2340 Beerse, Belgium.
Pharmaceutics
|February 27, 2026
Summary
This study demonstrates how drug properties and formulation variables influence in vitro drug release from in situ gel (ISG) long-acting injectables (LAIs). It also establishes an in vitro-in vivo correlation (IVIVC) for celecoxib ISGs, aiding LAI development.
Area of Science:
- Pharmaceutical Sciences
- Drug Delivery Systems
- Biomaterials
Background:
- Long-acting injectables (LAIs) are crucial for improving patient compliance.
- In situ gel (ISG) technology offers a promising approach for developing LAIs.
- Understanding drug release kinetics and establishing in vitro-in vivo correlations (IVIVCs) are vital for LAI formulation development.
Purpose of the Study:
- To investigate the impact of drug properties and formulation variables on in vitro drug release (IVR) from ISGs.
- To develop a point-to-point IVIVC for celecoxib-loaded ISGs.
- To support the development of effective LAI formulations using ISG technology.
Main Methods:
- Evaluated IVR of five model drugs (paracetamol, theophylline, felbinac, indomethacin, celecoxib) from ISGs using two poly(D,L-lactide-co-glycolide) (PLGA) grades (50:50 and 85:15 L/G ratios).
- Varied polymer/solvent ratios (30/70% and 40/60% w/w NMP) to assess formulation effects.
- Established a point-to-point IVIVC for celecoxib ISGs in rats by correlating deconvolution-derived fraction absorbed with in vitro fraction dissolved.
Main Results:
- Sustained IVR was observed, with release times varying significantly based on drug solubility and formulation.
- IVR rates increased with decreasing polymer lipophilicity and concentration, and increasing drug solubility.
- A point-to-point IVIVC was successfully established for celecoxib ISGs, demonstrating predictability of in vivo performance from in vitro data.
Conclusions:
- Drug solubility, polymer grade, and concentration significantly influence ISG IVR rates.
- The developed point-to-point IVIVC for celecoxib ISGs provides a valuable tool for formulation optimization.
- This research supports the rational design and development of LAIs utilizing ISG technology.
Keywords:
in situ gelsin vitro releasein vitro–in vivo correlationpharmacokineticssolubilitysustained releaseMore Related Videos
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