 The Phase I clinical trial in approximately 50 healthy volunteers will be conducted at a single clinical center in two stages. Stage 1 is an open-label, cross-over comparison of a single dose of Staccato Fentanyl and an equivalent dose of intravenous IV fentanyl. Stage 2 is a randomized, doubleblind, placebo-controlled dose escalation of Staccato Fentanyl, evaluating multiple doses of fentanyl. The three primary aims of the Phase I clinical trial are to evaluate the pharmacokinetics PK and absolute bioavailability for Fentanyl, compare the Staccato Fentanyl PK profile to the IV fentanyl PK profile, and examine the tolerability and safety of Staccato Fentanyl in a non-opioid-tolerant, healthy volunteer population. 