The objective of this study was to evaluate the safety and pharmacokinetics of unit dose budesonide (UDB), an aqueous dispersion of submicron-sized budesonide particles, and a commercially available budesonide suspension formulation. This was a randomized, double-blind, active-controlled, 4-period, 4-way crossover trial in 16 healthy, adult volunteers. Subjects received UDB 0.24, 0.12, and 0.06 mg or commercial budesonide 0.25 mg via a jet nebulizer. T-max was significantly (p < 0.05) earlier for UDB 0.06, 0.12, and 0.24 mg (4.5 +/- 3.3, 3.1 +/- 1.5, 3.7 +/- 1.5 min) vs. commercial budesonide (9.1 +/- 7.1 min). C-max was significantly (p < 0.05) higher for IUDB 0.24 mg vs. commercial budesonicle 0.25 mg (434.5 +/- 246.9 pg/mL vs. 303.5 +/- 177.4 pg/mL) but not between UDB 0.12 mg (239.9 +/- 140 pg/mL) and commercial budesonide 0.25 mg (p = 0.448). AUC(0-infinity) was marginally, but significantly lower for UDB 0.24 mg than commercial budesonicle 0.25 mg. AUCs for UDB 0.12mg were lower than commercial budesonicle 0.25 mg. UDB 0.24mg was absorbed more rapidly and achieved higher peak concentrations than commercial budesonide 0.25 mg, but had a lower AUC(0-infinity). UDB 0.12 mg also was absorbed more rapidly but had lower C-max and AUCs than commercial budesonicle 0.25 mg. (C) 2008 Published by Elsevier B.V.