Improved Oral Absorption of Carbamazepine from 1-O-Alkylglycerol Stabilized o/w Nanoemulsions

Absorption of carbamazepine (CBZ) from gastrointestinal tract is slow and erratic. In order to improve oral absorption of CBZ, 1-O-alkylglycerol/lecithin stabilized o/w nanoemulsions incorporating CBZ in oil phase were prepared and characterized. Nanoemulsions had a size around 200 nm. Their oral bioavailability in rabbits and in situ intestinal absorption in rats were evaluated. In in situ studies, the test and control systems were charged into intestine and instead of lumenal samples, blood samples from tail vein were analyzed for CBZ content. These results indicated faster rate and higher extent of absorption for nanoemulsions than control (a micron sized aqueous CBZ suspension). The high rate of release from and adherence of nano-oil particles to mucosa seems to have enhanced absorption of CBZ in this model. Among nanoemulsions 1-O-decylglycerol/lecithin stabilized system showed faster rate of absorption, higher Cmax and area under the curve (AUC). Improvement in oral absorption of CBZ from nanoemulsions was also evident from the bioavailability study conducted on rabbits. Peak serum concentration (Cmax) and AUC were higher for nanoemulsions than control. This study indicated increase in absorption and decrease in disposition of CBZ when administered as nanoemulsions. Broadly the globule size and permeabilization effect due to 1-O-alkylglycerols seem to be the factors responsible for enhanced absorption due to nanoemulsions in in situ and in vivo experiments. However the permeability effect of 1-O-alkylglycerol was prominent only in in situ experiments.