Formulation Screening of Palm-based Nanoemulsion for an Oral Drug Vehicle of Phyllanthin
Phyllanthus amarus is commonly used in traditional medicine, and the major lignins of the plant, namely, phyllanthin and hypophyllanthin, have been reported to possess hepatoprotective activity. However, phyllanthin exhibits low oral bioavailability and requires a large quantity of herbal extract for a longer duration of treatment, limiting the clinical use of phyllanthin. To overcome these drawbacks, nano-sized emulsion systems have gained increasing importance due to their ability to improve the gastrointestinal absorption of hydrophobic drugs. Proper selection of oils and surfactants, along with their suitable hydrophilic-lipophilic balance (HLB) value, is crucial to obtain stable, mild and clinically acceptable nanoemulsions. The focus of the present study is to provide an efficient screening approach for the excipient selection for the optimum nanoemulsion formulation development containing phyllanthin. The selection of oil was based on the solubilizing capacity of phyllanthin by HPLC analysis. The drug solubility in the oil was taken as the criterion for oil selection, and palm kernel oil ester was chosen as the oil phase in the nanoemulsion formulation. Emulsification ability of the surfactant was assessed for surfactant screening. Among them, Tween® 80 and Span® 80 were found to be an effective emulsifier for the oil phase. The desired HLB value for oil-in-water nanoemulsion is between 8 and 18. The nanoemulsion formulation was thermally stable and could be effectively used for drug delivery applications.