Recombinant human
interleukin-11 (rhIL-11) is a licensed
biological therapeutic product in at least one country and is used to combat
thrombocytopenia during chemotherapeutic regimens, as well as undergoing clinical trials for a range of other disorders. Following attempts to lyophilize
IL-11 at low concentrations, it was clear that a significant loss of recoverable
biological activity occurred. Investigation of a variety of factors, including the type of container in which the
rhIL-11 was lyophilized, revealed that surface adsorption to glass was a major factor resulting in loss of activity of
rhIL-11 in
solution (> 40% reduction after 3 h at room temperature), in addition to losses of activity post-lyophilization. To overcome this problem, different formulations containing combinations of
human serum albumin (HSA),
trehalose and Tween-20 have been investigated. Two formulations were successful in entirely preserving the
biological activity of
rhIL-11 through lyophilization and subsequent reconstitution (potency estimates of formulated relative to original material being > or =0.97). Accelerated degradation studies, performed at intervals over a six-month period, demonstrated the stability of freeze-dried
rhIL-11 using these formulations (predicted annual reduction in potency after storage at -20 degrees C < or =1.4%). In conclusion, we have developed a working combination of
excipients (0.5% HSA, 0.1%
trehalose and 0.02%
Tween-20 in
potassium phosphate buffer (pH 7.4)) to formulate a stable
rhIL-11 freeze-dried product in glass containers, with no loss in potency. These findings should facilitate development of low dose
rhIL-11 products and be an
indicator of caution to those using this and other material with similar physical properties, without taking appropriate precautions to avoid losses through adsorption.