Dietary supplements containing vitamins and minerals: Formulation, optimization and evaluation

The regular diet of common man is often deficient in certain nutrients, so dietary supplements are commonly prescribed. In this study, a combination of vitamins and minerals in the form of a bilayer tablet is proposed as a dietary supplement. A film-coated bilayer tablet in which one layer contains premixed vitamins (A, D, E, C, B1, B2, B3, B5, B6, B7, B9 and B12) and the other layer contains premixed minerals (magnesium, manganese, molybdenum, iodine, zinc, silicon and copper) was formulated by direct compression method. This uniquely formed bilayer tablet was assessed for physiochemical properties, microbial load and stability studies. FTIR studies revealed that there was no interaction between the vitamins, minerals and excipients used in the study. In vitro dissolution test revealed that >85% of folic acid and zinc sulphate were released in 60 min at pH 6.5–7.5. The release of folic acid was found to follow a first-order and Higuchi model, whereas zinc sulphate followed a first-order and Korsemeyer-Peppas model, indicating diffusion and erosion mechanism. The results of the long term and accelerated stability studies showed that, there were no changes in physicochemical properties and release pattern of bilayer tablets. Furthermore, the optimized formulation showed increase in the stability period for about 24 months. This nutritional supplement based on oral delivery of bilayer tablets is expected to gain more acceptance among the commercially available products due to better release properties and combination therapy.