White beeswax microspheres: a comparative in vitro evaluation of cumulative release of the anticancer agents fluorouracil and ftorafur.

White beeswax microspheres were investigated as a vehicle for the controlled release of anticancer agents. The in vitro diffusion of fluorouracil (1) and its prodrug ftorafur (2) was studied. The transfer rate constants from simulated gastro-intestinal juices to simulated plasma, throughout artificial wall lipid membranes, were defined. The constant's values suggested that the two drugs are poorly absorbed from stomach and main absorption occurred in the intestinal tract. Microspheres of 1 and 2 were prepared by a meltable dispersion of white beeswax and a wetting agent. The method is simple, inexpensive, rapid and reproducible. The drug release from the prepared microspheres was evaluated in vitro. More than 95% of the isolated microspheres were of particle size range 100-425 microns. The average drug content was 4%. Drug dissolution was greatly retarded as a result of microsphere formation.