Nebulized Fentanyl in Healthy Volunteers

3 administrations based on a weight-dependent threshold (40 µg per administration for a weight \< 70kg and 50 µg per administration for a weight ≥ 70kg).

3 administrations based on a weight-dependent threshold (20 µg/administration and for a weight \< 70kg and 30 µg/administration for a weight ≥ 70kg). The dose of each bolus will be distributed at equivalent volume in both nasal pits