Encapsulation of Vitamin A palmitate for animal supplementation: Formulation, manufacturing and stability implications

Two manufacturing methods and numerous formulative approaches have been evaluated to obtain a stable oral pharmaceutical form of Vitamin A palmitate (VAP), a substance very sensitive to light, temperature, humidity and metal ions. The best results were obtained by formulating VAP, stabilized with butylated hydroxytoluene (BHT), in double layer microcapsules constituted by a core of chitosan, Tween 20, CaCl2 and EDTA surrounded by a first chitosan-alginate membrane and an outer membrane of calcium-alginate. This formulation design enabled the production of beads with high drug loading (42% w/w) and high encapsulation efficiency (94%). The stability of VAP-loaded microcapsules was assessed according to EMEA guidelines. This formulation design showed the best performance in terms of VAP recovery (t50% > 360 days) after 1 year of storage at room conditions. This is a very important result considering the poor shelf-life (45 days) of pure VAP stabilized with BHT stored at the same conditions.