Zidovudine-cyclodextrin inclusion complex and its permeability across rat stomach and intestinal compartments

The permeability of zidovudine in zidovudine-cyclodextrin inclusion complex across stomach and intestinal compartments of rat was investigated spectrophotometrically. The absorption maximum ( ) for zidovudine in HCl max buffer (pH 1.2) and in phosphate buffer (pH 7.4) were 267 and 268 nm respectively. The inclusion complex wasformed by freeze-drying method and the stoichiometric ratio was determined to be 1:1. Infra-red spectrophotometry was used to confirm the formation of the inclusion complex. Buffered solutions of the inclusion complex were introduced into the stomach (HCl buffer, pH 1.2) and intestine (phosphate buffer, pH 7.4) immersed in appropriatebuffer solution. In the stomach, after 60 min, the transport of zidovudine increased by between 50 and 55 % above that of zidovudine alone; while in the intestine the increase was between 10 and 15 %. In both tissues the steady state condition for zidovudine alone occurred after 4 h while that for the inclusion complex occurred after 3 h. These figuressuggest that B - cyclodextrin facilitated the transport of zidovudine across these tissues and so we intrapolate that Bcyclodextrincan improve the bioavailability of zidovudin