The need to administer GH by daily injection has been long known to lower compliance in children, impacting treatment efficacy. An alternate method of delivery has been the “holy grail” for decades. The authors from this report note that advances in aerosol technology that increase particle size and lower their density and tendency to agglomerate have resulted in increased efficiency of deep lung delivery and systemic absorption. In this short-term (7 day) randomized, double-blind, placebo-controlled cross-over trial (sponsored by Eli Lilly and Co.), Walvoord et al. compare somatropin inhaled powder (SIP) to subcutaneous (SC) GH in GH deficient children. The authors note that previous 6-month toxicology studies in primates and studies in healthy adult volunteers demonstrated acute safety and tolerability of SIP, with no negative effects on pulmonary function tests (including studies in patients with asthma). The time course of serum GH concentrations over 12 hrs (pharmacokinetics) was similar between SIP and SC GH, with perhaps somewhat faster absorption of SIP. Increases in serum IGF-1 over baseline (pharmacodynamics) again was similar between SIP and SC GH. It should be noted that SIP doses were selected to be equivalent to SC GH, which previous studies in adults showed required a SIP:SC ratio of 16.7:1. In this study, the “bioavailability” of SIP in children was 3.5%, about half of that in adults. There was no evidence of an effect of SIP on pulmonary function tests, done at 24 hrs and day 8 of the study. By questionnaire, all 22 subjects preferred inhaled GH rather than daily injections. Again, it should be noted that proper use of the inhaler is required, such that the youngest subjects were 6 years of age. In summary, the investigators demonstrated the feasibility of inhaled GH treatment. Issues of relatively low bioavailability in children need to be resolved, and then, presumably, the investigators plan to carry out studies to evaluate the safety of long-term inhaled GH in children. Steve LaFranchi, MD