Phase-separated polymer blends for controlled drug delivery by tuning morphology

Controlling drug release rate and providing physical and chemical stability to the active pharmaceutical ingredient are key properties of oral solid dosage forms. Here, we demonstrate a formulation strategy using phase-separated polymer blends where the morphology provides a route for tuning the drug release profile. By utilising phase separation of a hydrophobic and a hydrophilic polymer, the hydrophilic component will act as a channelling agent, creating a porous network upon dissolution that will dictate the release characteristics. With ptychographic X-ray tomography and scanning transmission X-ray microscopy we reveal how the morphology depends on both polymer fraction and presence of drug, and how the drug is distributed over the polymer domains. Combining X-ray imaging results with dissolution studies reveal how the morphologies are correlated with the drug release and showcase how tuning the morphology of a polymer matrix in oral formulations can be utilised as a method for controlled drug release.

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Preparations of melt-extruded filaments

Nicotinamide (Thermo Fisher, Germany), AFFINISOL HPMC HME 4M (Dow Wollf, Germany) and PLA (NatureWorks LLC, USA) were weighed and physically mixed in a 6 g batch with 0 and 10 wt% nicotinamide in polymer fractions of 30/70, 50/50 and 70/30 PLA/HPMC. The AFFINISOL HPMC HME 4M was selected due to the significantly lower glass transition temperature and melt viscosity as compared to other available grades of HPMC. The mixtures were fed via a hopper into the barrel of a 5 mL capacity Xplore micro compounder with two conical mixing screws and a circular die of ∅ = 1.5 mm. The barrel temperature was set to 180 °C, screw speed of 50 rpm, with a mixing time of 6 min.

Olsson, M., Storm, R., Björn, L. et al. Phase-separated polymer blends for controlled drug delivery by tuning morphology. Commun Mater 5, 231 (2024). https://doi.org/10.1038/s43246-024-00678-y