Vitamin B₃ Intercalated in Layered Double Hydroxides: A Drug Delivery System for Metabolic Regulation

The organic compound niacin or nicotinic acid, also known as vitamin B₃ (VitB₃), is essential for human nutrition and metabolic regulation. However, in high doses, it can provoke side effects, such as hyperglycemia, liver damage, and flushing. Development of a controlled release system that slowly releases VitB₃ into the organism would avoid high dosing peaks, thus contributing to decrease the occurrence of side effects in nutritional supplementation. Here, we show that the slow and controlled release of VitB₃ in an acid environment can be achieved via its intercalation in layered double hydroxides (LDHs). The synthesis of a ZnAl-VitB₃ system is shown, in which VitB₃ is intercalated in a ZnAl LDH. The presence of VitB₃ in the ZnAl-VitB₃ system was confirmed by elemental analysis, infrared (FTIR) and NMR spectroscopy, while successful intercalation in the LDHs was revealed by powder X-ray diffraction (PXRD). In vitro release tests were carried out in a concentrated HCl solution of pH 1.5, a pH similar to the human stomach environment. The results showed a steady release of VitB₃ from the LDH host, with 90% of the vitamin liberated in the first 60 min after the suspension of the LDH in the acidic solution.