Formulation Screening of Palm-based Nanoemulsion for an Oral Drug Vehicle of Phyllanthin

Phyllanthus amarusis 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 herbalextract for a longer duration of treatment, limiting the clinical use of phyllanthin. To overcomethese drawbacks, nano-sized emulsion systems have gained increasing importance due to theirability to improve the gastrointestinal absorption of hydrophobic drugs. Proper selection of oilsand surfactants, along with their suitablehydrophilic-lipophilic balance(HLB) value, is crucial toobtain stable, mild and clinically acceptable nanoemulsions.The focus of the present study is toprovide an efficient screening approach for the excipient selection for the optimum nanoemulsionformulation development containing phyllanthin. The selection of oil was based on the solubilizingcapacity of phyllanthin by HPLC analysis. The drug solubility in the oil was taken as the criterionfor oil selection, and palm kernel oil ester was chosen as the oil phase in the nanoemulsionformulation. Emulsification ability of the surfactant was assessed for surfactant screening. Amongthem, Tween®80 and Span®80 were found to be aneffectiveemulsifier for the oil phase. Thedesired HLB value for oil-in-water nanoemulsion is between 8 and 18. The nanoemulsionformulation was thermally stable andcouldbe effectively usedfor drug delivery applications.