The effect of formulation variables on the physicochemical and antimicrobial properties of cream formulations of Phyllanthus amarus whole plant extract

Background: Phyllanthus amarus Schum and Thonn (Euphorbiaceae) is a plant of ethnomedicinal importance whose cream formulations have shown antimicrobial properties in a previous study.

Objective: To determine the quantitative effects of formulation additives on the physicochemical and antimicrobial properties of Phyllanthus amarus cream.

Methods: The ethanol extract of Phyllanthus amarus was prepared by maceration for 72 hours and the cream formulated and assessed using established procedures. The individual and interaction effects of nature (N) of humectant, concentration (C) of humectant and extract concentration (E) on the physicochemical and in vitro antimicrobial properties of the cream formulation were determined using a 23 factorial experimental design.

Results: The independent coefficient values ranked N>C >E on viscosity, E>N>C on globule size and C >E > N on spreadability. The ranking on antibacterial property was E > N > C, while on fungi it changed to E > C > N. The physicochemical properties of the formulations were differently influenced by N, C and E. The individual and interaction effects on the physicochemical and antimicrobial properties were found to be significant (p<0.05). 

Conclusion: In the design of P. amarus cream, careful consideration of formulation variables is required to obtain optimum physicochemical and antimicrobial properties.