Oral Bioavailability of flutamide from 1-O-alkylglycerol stabilized o/w nanoemulsions

Size of oil globule and emulsifier film covering it are the key factors modifying oral absorption of drugs dissolved/dispersed in oil globules of o/w emulsions. Since oral bioavailability of flutamide (FTM) is poor, nanoemulsions incorporating FTM in oil phase and globules stabilized by a novel lipophilic emulsifier, 1-O-alkylglycerol were developed and characterized. All nanoemulsions had a size around 200 nm. They exhibited considerable release retardation in vitro. Flutamide nanoemulsions were evaluated for oral bioavailability in rabbits and in situ intestinal absorption in rats. Serum level data of flutamide obtained in the in situ experiments indicate higher FTM absorption from nanoemulsions than the aqueous FTM suspension. Among the nanoemulsions, 1-O-alkylglycerol stabilized systems showed higher absorption. The results of bioavailability studies in rabbits indicate increased absorption and decreased elimination of FTM from nanoemulsions, thus improving the bioavailability. Increased rate of absorption of flutamide in the in situ experiments can be attributed to the permeation enhancement effect of 1-O-alkylglycerols. However, size of the oil droplet seems to be the major factor in improving oral bioavailability in rabbits.