Novel approach for overcoming the stability challenges of lipid-based excipients. Part 2: Application of polyglycerol esters of fatty acids as hot melt coating excipients

Filament-based 3D-printing of placebo dosage forms using brittle lipid-based excipients

In order to expand the limited portfolio of available polymer-based excipients for fabricating three-dimensional (3D) printed pharmaceutical products, Lipid-based excipients (LBEs) have yet to be thoroughly investigated. The technical obstacle of LBEs application is, however their crystalline nature that renders them very brittle and challenging for processing via 3D-printing. In this work, we evaluated the functionality of LBEs for filament-based 3D-printing of oral dosage forms. Polyglycerol partial ester of palmitic acid and polyethylene glycols monostearate were selected as LBEs, based on their chemical structure, possessing polar groups for providing hydrogen-bonding sites. A fundamental understanding of structure-function relationship was built to screen the critical material attributes relevant for both extrusion and 3D-printing processes. The thermal behavior of lipids, including the degree of their supercooling, was the critical attribute for their processing. The extrudability of materials was improved through different feeding approaches, including the common powder feeding and a devised liquid feeding setup. Liquid feeding was found to be more efficient, allowing the production of filaments with high flexibility and improved printability. Filaments with superior performance were produced using polyglycerol ester of palmitic acid. In-house designed modifications of the utilized 3D-printer were essential for a flawless processing of the filaments.

Going green: Development of a sustainable lipid-based enteric coating formulation for low-dose aspirin multiparticulate systems

There is a rising awareness of pharmaceutical industry of both patient-centric and sustainable product development. Manufacturing of multiparticulate systems (MPS) with functional coating via solvent-free hot melt coating (HMC) can fulfill both requirements. An innovative lipid-based formulation was developed with the composition of palmitic acid and Grindsted® citrem BC-FS (BC-FS) for enteric coating of acetylsalicylic acid (ASA). The ASA crystals were directly hot melt coated to produce user-friendly low-dose ASA MPS for thromboembolism prophylaxis. Prior to HMC, rational boundaries for the process temperature were defined based on the melting and crystallization behavior of coating blend. Stability of coating in terms of resistance to heat stress and solidstate stability were screened via Fourier-transform infrared spectroscopy and x-ray diffraction. Exposure of coating blend to 100 °C for two hours did not cause any chemical degradation. Crystal growth of palmitic acid and polymorphic transformation in BC-FS were observed after storage under accelerated conditions, however did not significantly affect the ASA release from coating. The developed formulation is a unique solvent-free, lipid-based enteric composition and paves the way for sustainable green pharmaceutical manufacturing.

Lipid-microparticles for pulmonary delivery of active pharmaceutical ingredients: Impact of lipid crystallization on spray-drying processability

Spray-drying is an extensively used technology for engineering inhalable particles. Important technical hurdles are however experienced when lipid-based excipients (LBEs) are spray-dried. Stickiness, extensive wall deposition, or simply inability to yield a solid product have been associated to the low melting points of LBEs. In this work, solutions containing polyglycerol esters of behenic acid (PGFA-behenates), or other high melting point LBEs, were spray-dried to produce ibuprofen (IBU)-loaded inhalable lipid-microparticles. Prior to spray-drying, rational boundaries for the outlet temperature of the process were defined using LBE-IBU phase diagrams. Despite spray-drying the solutions at outlet temperatures below the boundaries, process performance and yield among LBEs were entirely different. Lipid crystallization into polymorphs or multi-phases negatively impacted the yield (10-47%), associated to liquid fractions unable to recrystallize at the surrounding gas temperature in the spray-dryer. The highest yields (76-82%), ascribed to PGFA-behenates, resulted from monophasic crystallization and absence of polymorphism. Lipid-microparticles, composed of a PGFA-behenate, were characterized by a volume mean diameter of 6.586 µm, tap density of 0.389 g/cm³ and corrugated surface. Application as carrier-free dry powder for inhalation resulted in high emitted fraction (90.9%), median mass aerodynamic diameter of 3.568 µm, fine particle fraction of 45.6% and modified release in simulated lung fluid.