Development and in vitro/in vivo performance of self-nanoemulsifying drug delivery systems loaded with candesartan cilexetil.
The intestinal absorptive characteristics and the efflux mechanisms of candesartan (CDS), a novel angiotensin II type 1 receptor blocker, were investigated. The Caco-2 cells were used as models of the intestinal mucosa to assess uptake and transport of CDS. The determination of CDS was performed by HPLC-Flu. In the Caco-2 cells, the uptake and absorptive transport of CDS were pH-independent (in the pH range 6.0-8.0). Passive membrane diffusion dominates the absorptive transport behavior of CDS across Caco-2 cells, while secretory transport was a concentration-dependent and saturable process. In the presence of cyclosporin A and verapamil, potent inhibitors of P-glycoprotein (P-gp), the P(ratio) decreased from 3.8 to 2.3 and 1.8, respectively, and permeation of apical to basolateral was enhanced. Overall, the current study suggests that efflux transporters are capable of mediating the absorption and secretion of CDS, and they may play significant roles in limiting the oral absorption of CDS.