Intranasal delivery of recombinant human growth hormone (somatropin) in sheep using chitosan-based powder formulations

The effectiveness of chitosan in promoting the intranasal bioavailability of recombinant human growth hormone (hGH) has been evaluated. hGH was formulated with chitosan to produce a powder blend (Formulation A) and granules (Formulation B) for intranasal administration. The in vivo pharmacokinetic performance of the formulations was evaluated in a group of six sheep in a randomised crossover study. A subcutaneous injection of hGH solution was administered as a control. The intranasal and subcutaneous doses of hGH were 0.3 and 0.03 mg/kg, respectively. The intranasal formulations appeared to be well tolerated. Mean bioavailabilities of hGH from Formulations A and B were 14 and 15%, respectively relative to subcutaneous injection. It is concluded that chitosan-based intranasal powder formulations may provide a practical means for non-injectable delivery of hGH and, potentially, other therapeutic protein molecules.