Enteric Coated Oral Delivery of Hydroxyapatite Nanoparticle for Modified Release Vitamin D3 Formulation

Abstract

Vitamin D3 (VD) and calcium phosphate play a vital role in bone homeostasis. Factors such as obesity or gastrointestinal problems can render the use of pure VD and calcium phosphate supplements ineffective. This study investigated the possibility of using VD-loaded hydroxyapatite nanoparticles for the codelivery of VD and Ca3(PO4)2. Due to the high affinity of Ca3(PO4)2 for bone tissue, HA is an ideal delivery system to deliver VD to target tissue. Herein, HA nanoparticles were synthesized and loaded with VD using a vacuum evaporation method. The synthesized HA-VD nanoparticles were morphologically and chemically characterized by SEM, FTIR, and TGA. The system exhibited a two-stage release pattern, which includes a first-day burst release (35%) and sustained release for a further ten days. The cytocompatibility and cell penetrative ability of the nanoparticle system were assessed in vitro using preosteoblast cells: the system is nontoxic and well-tolerated. Finally, the VD-loaded HA nanoparticles were coated with a gastroresistant polymer, hypromellose phtalate-55 (HP-55) in order to protect the pH-sensitive HA from degradation at lower pHs. A coaxial electrospray technique was employed to achieve this. In all, the tested HA-VD system is a viable alternative for codelivery of VD, Ca2+, and PO43- to their target tissues.