text: Abstract 1. We investigated the effects of the dose of and the number of times an inducer was administered and the duration of induction of hepatic and intestinal cytochrome P450 3A (<< CYP3A >>) in rats using [[ dexamethasone 21-phosphate ]] (DEX-P) and midazolam (MDZ) as an inducer and a substrate to CYP3A, respectively.