Ilaprazole metabolites, ilaprazole sulfone and ilaprazole sulfide decreased the affinity of ilaprazole to bovine serum albumin

► Affinities of IPZ and its metabolites IPZO and IPZI to BSA were investigated. ► Binding of IPZ, IPZO and IPZI to BSA primarily took place in subdomain IIA. ► IPZO and IPZI decreased affinities of IPZ to BSA. ► IPZO and IPZI had competitive binding site with IPZ.