Enhancement of bioavailability of cinnarizine from its beta-cyclodextrin complex on oral administration with DL-phenylalanine as a competing agent.
The present investigation is concerned with an improvement of the bioavailability of cinnarizine by administering its beta-cyclodextrin complex together with another compound which competes with the beta-cyclodextrin molecule in complex formation in aqueous solution (competing agent). The bioavailability of cinnarizine on oral administration of the cinnarizine-beta-cyclodextrin inclusion complex was enhanced by the simultaneous administration of DL-phenylalanine as a competing agent, e.g., the AUC was 1.9 and 2.7 times as large as those of the cinnarizine-beta-cyclodextrin complex alone and cinnarizine alone, respectively. The enhancement of AUC and Cmax completely depended on the dose of DL-phenylalanine. It was found from these results that DL-phenylalanine acted as a competing agent in the GI tract and the minimum effective dose required of DL-phenylalanine might be 1 g for 50 mg of cinnarizine in the cinnarizine-beta-cyclodextrin complex. Evaluating the competing effect of DL-phenylalanine in vitro using an absorption simulator, it was found that the decreased penetration rate of cinnarizine through the artificial lipid barrier with addition of beta-cyclodextrin was restored with the addition of DL-phenylalanine.
D000284:Administration, Oral; D000818:Animals; D001667:Binding, Competitive; D001682:Biological Availability; D002936:Cinnarizine / Q000378:metabolism*; D003505:Cyclodextrins; D004285:Dogs; D007408:Intestinal Absorption; D010649:Phenylalanine / Q000378:metabolism*; D013997:Time Factors; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D047392:beta-Cyclodextrins; D002936:Cinnarizine; D010649:Phenylalanine; C031215:betadex