Development of Oral Microemulsions of <i>Morus alba</i> Extract for Osteoarthritis

Abstract

This study aimed to develop oral microemulsions (MEs) containing M. alba extract. The stability study of the extract incorporated in the ME was also included. First, pseudo-ternary phase diagrams were constructed using caprylic/capric triglyceride (oil), PEG-8 caprylic/capric glycerides (S), polyglyceryl-3 diisostearate (CoS). Propylene glycol (PG) was used as a cosolvent. Then, the formulations were chosen to incorporate MSE and subjected to stability testing at 4o C, room temperature (RT) and 45o C at 75% RH for 8 weeks. Physical stability of the formulations was assessed by visual observation on the precipitation, phase separation and cloud point. Chemical stability was determined by quantitative analysis of oxyresveratrol using high performance liquid chromatography (HPLC). The results showed that with increasing the ratio of S/CoS, the area of ME existing region in phase diagrams increased. The addition of PG into aqueous phase at ratio 1:1 slightly affected the formation of MEs. Physical stability was not affected by temperature but was influenced by the components of the formulations. However, degradation of the extract was affected by both temperature and components of the formulations. The extract was stable at 4o C and RT. However, at 45o C, it degraded about 16-57%, depending on the components of the formulations. The best ME formulation consisted of 10% caprylic/capric triglyceride, 80% PEG-8 caprylic/capric glycerides and polyglyceryl-3 diisostearate (4:1), and 10% water and PG (1:1).