Comparison of the pharmacokinetics, safety and tolerability of two concentrations of a new liquid recombinant human growth hormone formulation versus the freeze-dried formulation

BACKGROUND: Somatropin is recombinant human growth hormone (GH) used for the treatment of growth failure in children and GH deficiency in adults. Two concentrations of a liquid formulation have been developed: 5.83 and 8.0 mg/mL. This trial compared the pharmacokinetics (PK), safety and tolerability of these two liquid concentrations against the freeze-dried (FD) formulation in healthy volunteers. METHODS: In an open-label, single-centre, three-way crossover study, volunteers (aged 18-45 years) were given subcutaneous injections of the reconstituted FD and two liquid formulations in random sequential order, each at 4 mg/dose, with a 1-week wash-out period between doses. To suppress endogenous GH secretion, intravenous somatostatin was infused continuously 1 hour before to 24 hours after each dose, achieving a cumulative dose of 3 mg. Primary PK endpoints were area under the serum concentration-time curve (AUC(0-t)) and maximum serum concentration (C(max)). For each of the two liquid formulations, bioequivalence with the FD formulation was concluded if the 95% confidence intervals (CIs) for the estimated test/reference ratios of geometric means of AUC(0-t )and C(max )were within the standard pre-specified acceptance range (0.80-1.25). RESULTS: Fifteen men and 15 women enrolled (safety population, n = 30; PK population, n = 28). Bioequivalence with the FD formulation could be shown for both liquid formulations. The ratios of geometric means (95% CI) were 1.046 (0.980, 1.117) and 0.991 (0.929, 1.058) for AUC(0-t )and 0.954 (0.875, 1.040) and 0.955 (0.876, 1.041) for C(max )for the 5.83 and 8.0 mg/mL formulations, respectively. No significant differences between the three treatments in half-lives, time to reach C(max), clearance or volume of distribution were observed. After injection, the most common side-effects were pain or injection-site reactions (all of mild intensity). There were no clinically significant abnormal vital signs, ECG or laboratory findings. There were 56 treatment-related adverse events (AEs): 49 mild, 6 moderate and 1 severe (vomiting). No serious AEs occurred. The pattern of AEs was as expected and all resolved by study end. CONCLUSION: Both concentrations of a new liquid multi-dose formulation are bioequivalent to the FD reference formulation and all are well tolerated. TRIAL REGISTRATION NUMBER: NCT01034735.