Inhaled GH has low bio-availability in children

Growth hormone (GH) can be delivered to paediatric patients via an inhaler but it is not absorbed into the body as effectively as it is in adults, a proof of principle study finds. The randomised, double-blind, double-placebo crossover study, published in the Journal of Clinical Endocrinology and Metabolism, followed 22 children aged 6 to 16 with growth hormone deficiency for 7 days and found “no safety concerns” with the treatment. Each subject in the study received a daily injection and inhalation of 0.01-0.11mg/kg injected Humatrope (Hsc) or 0.16-1.87mg/kg somatropin inhalation powder (SIP). The study’s authors found that GH absorption appeared to be faster in the inhalation group (maximum serum concentrations at 1-4 hours compared to 2-8). They said that their research showed that “increasing doses of inhaled SIP result in increasing serum GH levels that are similar to the serum levels seen after Hsc injection.” Furthermore, all of the children in the study preferred the inhalation method over the injection method. However the study also found that mean relative bioavailability for inhaled GH was 3.5%, which the authors said was less than half what was seen in their previous tests of SIP in adults. “Although children preferred this route of therapy, the bioavailability results of this study have delayed ongoing development of SIP,” the authors said. “Clearly more extensive studies are required to resolve issues related to relatively low bioavailability and to define the long-term efficacy and safety of this novel approach to large molecule, systemic therapy.” Journal of Clinical Endocrinology and Metabolism...