Optimization of bilayer tablet manufacturing process for fixed dose combination of sustained release high-dose drug and immediate release low-dose drug based on quality by design (QbD)

A fixed dose combination (FDC) bilayer tablet, consisting of high-dose metformin HCl in a sustained release layer and low-dose evogliptin tartrate in an immediate release layer, was developed based on a quality by design (QbD) approach. To implement QbD approach, the bilayer tableting process parameters judged as high risk through risk analysis were optimized by a central composite face-centered design as a design of experiment (DOE) methodology. Using DOE, the optimized conditions of the tableting process for drug products that satisfy the established quality target product profiles were obtained. The content uniformity of low-dose evogliptin tartrate in the optimized bilayer tablet prepared on a large scale was confirmed by at-line transmittance Raman spectroscopy as a process analytical technology. In addition, the in vitro drug release and in vivo pharmacokinetic studies showed that metformin HCl and evogliptin tartrate in the bilayer tablet is bioequivalent to those of the respective reference drugs. Furthermore, the physicochemical stability of the optimized bilayer tablet during storage under long-term and accelerated conditions was also confirmed. Therefore, it can be concluded that the QbD approach is an effective way to develop a new FDC bilayer tablet that is easy to scale up for successful commercialization.