Sterilisation of biopharmaceuticals: Effect of gamma irradiation, e-beam irradiation and nitrogen dioxide on human insulin

Biopharmaceuticals are administered parenterally and therefore sterility is required. Sterility can be obtained via different processes including exposure to steam or dry heat. Sterilisation studies on biopharmaceuticals, which are highly sensitive medicinal products, are scarce. This study investigates the effect of different sterilisation processes on recombinant human insulin in solid state (gamma and e-beam irradiation (w/wo dry ice), nitrogen dioxide (NO₂)) and in aqueous solution (gamma irradiation (w/wo dry ice, w/wo glycerin)) using ultra-high performance liquid chromatography-diode array detection-mass spectrometry. It is observed that NO₂ substantially degrades the solid samples, while gamma and e-beam irradiation result in lower levels of degradation (mean normalized peak areas of 95.2-96.2 % with respect to the non-sterilised samples). Gamma irradiation of insulin solutions with and without dry ice at 2.5 kGy results in mean normalised peak areas of 85 % and <40 % with respect to the non-sterilised samples, respectively. It is concluded that sterilisation using ionising radiation of liquid biopharmaceuticals with insulin and sterilisation of insulin dry powder using NO₂ is less suitable with the set-ups used here because of substantial degradation. In contrast, evidence is presented in favour of sterilisation of insulin dry powder using ionising radiation.