Blood samples for cortisol dosage are performed immediately before the first session (baseline cortisol = C0), 24 hours after the first session (cortisol after a single dose of etomidate = C1), 24 hours after the third session (cortisol after 3 doses of etomidate = C3) and 24 hours after the sixth session (cortisol after six doses of etomidate = C6). All blood samples are performed at 9 and collected in normal tube.