The pharmacokinetics of chelerythrine solution and chelerythrine liposomes after oral administration to rats.

Chelerythrine is a quaternary benzo[c]phenanthridine alkaloid which has many potent pharmacological effects and can dissolve well in water; dihydrochelerythrine has recently been identified as a chelerythrine metabolite in rat. Most methods of preparation of liposomes suffer from the drawback of poor incorporation of water-soluble drugs. The emulsion/solvent evaporation method is a relatively simple and efficient way to prepare liposomes loaded with hydrophilic drugs. The aim of this study was therefore to find a suitable formulation to enhance the incorporation of chelerythrine into liposomes by the emulsion/solvent evaporation method and so improve the therapeutic efficacy of chelerythrine. Results showed that the chelerythrine-liposome has been successfully prepared by the emulsion/solvent evaporation method: the entrapment efficiency of chelerythrine was higher at 78.6 %, and the drug loadings reached 7.8 %. The relative bioavailability of chelerythrine and its dihydro derivative in liposomes was significantly increased compared with that of the chelerythrine solution. The area under the plasma concentration-time curve values of chelerythrine and dihydrochelerythrine after oral administration of chelerythrine-liposomes were 4.83-fold and 2.02 higher than those obtained with the chelerythrine solution. The half time and peak concentrations of chelerythrine and dihydrochelerythrine were also higher for chelerythrine-liposomes than that for chelerythrine. In contrast, the total body clearance and apparent volume of distribution were lower for chelerythrine-liposomes in comparison to the respective parameters for the chelerythrine solution. It can thus be concluded that incorporation into liposomes prolonged chelerythrine retention within the systemic circulation. Georg Thieme Verlag KG Stuttgart · New York.