EvaLuation of Intestinal Absorption of Ginsenoside Rg1 incorporated in microemulison using parallel artificial membrane permeability assay

Abstract

In the present study, ginsenoside Rg1 (Rg1), a naturally occurring drug which is hardly absorbed in gastrointestinal (GI) tract due to its high hydrophilicity and low membrane permeability, was incorporated in different compositions of water-in-oil microemulsions (MEs). And parallel artificial membrane permeability assay (PAMPA) that have been mainly utilized for the evaluation of in vitro permeability of early drug candidates was introduced in present study, as well as rat in vivo pharmacokinetics and in vitro permeability measurements, to investigate the effect of w/o ME on Rg 1 absorption. Correlation between various models as mentioned above was further performed to estimate the feasibility of PAMPA in the application of pharmaceutical preparation studies. After being administrated intraduodenally to rats, most of MEs can enhance the intestinal absorption of Rg1 to various extents with relative bioavailability (Fre) ranging from 268 to 1270% using drug solution as control. This enhanced absorption of Rg 1 may be related to its increased membrane permeability induced by ME as exhibited in the PAMPA and rat in vitro permeability measurements. Meanwhile, rat in vivo pharmacokinetics-PAMPA correlation (r2=0.6082) is significant (p<0.05) for ME, representing a potential prospect for the application of PAMPA in the study of pharmaceutical preparation in some conditions. © 2009 Pharmaceutical Society of Japan.