Bioequivalence of two recombinant interferon alpha-2b liquid formulations in healthy male volunteers.

Objective: Interferon (IFN) alpha-2b is a protein with antiviral, antiproliferative and immunoregulatory properties that is approved for several clinical indications. A new liquid, albumin-free, IFNalpha-2b formulation has recently been developed. This study aimed to evaluate the equivalence of the pharmacokinetic, pharmacodynamic and safety properties of the new formulation with a reference one in healthy male volunteers.
Methods: A randomised, crossover, double-blind study with a 3-week washout period was performed in which Heberon Alfa R (formulation A) and Viraferon (formulation B) were compared. A single 20 x 10(6) IU IFNalpha-2b dose was administered subcutaneously to 14 apparently healthy male subjects. Serum IFN level was measured over 48 hours by enzyme immunoassay (EIA) and by antiviral activity titration. Clinical and laboratory variables were determined, as were pharmacodynamic and safety criteria.
Results: Groups were homogeneous with regard to all demographic and baseline variables. Pharmacokinetic comparison by EIA did not show differences between the formulations: area under the curve (AUC) 2572 versus 2561 ng x h/L, maximum plasma concentration (Cmax) 318 versus 354 ng/L, time to Cmax (tmax) 8.2 versus 8.5 h, elimination half-life (t(1/2)) 5.87 versus 6.08 h, terminal elimination rate (lambda) 0.122 versus 0.118 h(-1), and mean residence time (MRT) 10.9 versus 12.0 h for formulations A and B, respectively. The differences never reached 20%, which is the clinically significant threshold. The 90% confidence interval of the ratio between them was in all cases within the 0.8, 1.25 range. The two formulations were clinically equivalent with regard to serum IFN antiviral activity titration (0.8, 1.25 criterion) regarding their pharmacokinetic parameters. There were no significant differences with respect to the pharmacodynamic variables: serum beta2-microglobulin and temperature increase. Heart rate and blood pressure changes did not differ either. Both products provoked similar haematological count decreases and had similar safety profiles. The most frequent adverse reactions were fever, tachycardia, headache and arthralgias.
Conclusion: The overall analysis strongly suggests the bioequivalence of these two products.
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