Stability of Recombinant Consensus Interferon to Air‐Jet and Ultrasonic Nebulization

The stability of recombinant consensus α‐interferon (rConIFN) to air‐jet and ultrasonic nebulization was evaluated. Volumes of 10 mL of 0.5mg/mL rConIFN in phosphate‐buffered saline (PBS) at pH 6.3 were nebulized with a Collison three‐jet nebulizer at 40 psig (10 L/min) for up to 25 min. The effects of pH (3.0, 6.3, and 9.0), additive (0.1% w/v Tween 80, 0.1% w/v Tween 20, and 1% w/v PEG 8000), and ionic strength (0, 0.25, and 1.0) were examined. The effects of ultrasonic nebulization were studied using three devices (DeVilbiss “Aerosonic”; Mountain Medical “Microstat”, and Medix “Easimist”). Stability of rConIFN was assessed by size exclusion chromatography and native and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). Structural effects were examined by circular dichroism spectroscopy and bioactivity was assessed by anin vitromitogenic inhibition bioassay. rConIFN is destabilized by air‐jet nebulization. Insoluble noncovalent aggregates are produced rapidly, and only ≈25% of the initial monomeric protein remains after 25 min of nebulization. This correlates with a decrease inin vitrobioactivity. Aggregation during nebulization is influenced by pH (9.0