Stabilization benefits of single and multi-layer self-nanoemulsifying pellets: A poorly-water soluble model drug with hydrolytic susceptibility

Solidified self-nanoemulsifying drug delivery systems (SNEDDS) offer strong option to enhance both drug aqueous solubility and stability. The current study was designed to evaluate the potential stabilization benefits of solidifying cinnarizine (CN) liquid SNEDDS into single and multi-layer self-nanoemulsifying pellets (SL-SNEP and ML-SNEP, respectively). The selected formulations were enrolled into accelerated, intermediate and long-term stability studies. The chemical stability was assessed based on the % of intact CN remaining in formulation. The physical stability was assessed by monitoring the in-vitro dissolution and physical appearance of the formulations. The degradation pathway of CN within lipid-based formulation was proposed to involve a hydroxylation reaction of CN molecule. The chemical stability study revealed significant CN degradation in liquid SNEDDS, SL-SNEP and ML-SNEP (lacking moisture-sealing) within all the storage conditions. In contrast, the moisture sealed ML-SNEP showed significant enhancement of CN chemical stability within the formulation. In particular, ML-SNEP coated with Kollicoat Smartseal 30D showed superior CN stabilization and no significant decrease in dissolution efficiency, at all the storage conditions. The observed stability enhancement is owing to the complete isolation between CN and SNEDDS layer as well as the effective moisture protection provided by Kollicoat Smartseal 30D. Hence, the degradation problem could be eradicated completely. The incorporation of silicon dioxide had an important role in the inhibition of pellet agglomeration upon storage. Accordingly, ML-SNEP coated with Kollicoat Smartseal 30D and/or silicon dioxide could be an excellent dosage form that combine dual enhancement of CN solubilization and stabilization.