Calcium Phosphate Microcapsules as Multifunctional Drug Delivery Devices

Abstract More challenging active pharmaceutical ingredients are entering the market, spurring the introduction of novel drug delivery strategies that necessitate a paradigm shift from exhausted excipients to materials with combined actions and multiple functionalities. In this study, an inorganic calcium phosphate microparticle with a hollow internal structure is introduced as a biocompatible and multifunctional microcapsule: the template inverted particle (TIP). A robust process is presented to create a unique particle geometry, which is characterized by a particle size of 20 µm and a hollow cavity enclosed by a specially engineered porous shell. This study focuses on the characterization of TIP as an excipient for the design of solid dosage forms. The cavities in the particle centers serve as an encapsulation space, resulting in boosted water uptake capacity of 5.3 cm 3 g −1 . Benefiting from the material's high wettability and water uptake rates, TIP tablets immediately disperse in the oral cavity. Mechanistic studies reveal a viscoelastic behavior of empty TIP microcapsules in accordance with the Kelvin–Voigt model of a parallel spring‐dashpot configuration. The unique particle geometry is maintained during compaction thanks to its exceptional structural integrity. This study demonstrates how multifunctional TIP microcapsules can be applied as a pharmaceutical drug delivery device.