Human α 1 -proteinase inhibitor (Respreeza ® ) in α 1 -antitrypsin deficiency emphysema: a profile of its use in the EU, Abstract Augmentation therapy with human α1-proteinase inhibitor (Respreeza®) is an effective and generally well tolerated treatment option for patients with severe α1-antitrypsin deficiency. In the 2-year RAPID trial, intravenous Respreeza 60 mg/kg once weekly was associated with a trend towards reduced mean annual rate of lung density loss (as measured by computed tomography) at total lung capacity (TLC) and functional residual capacity (FRC) combined, and at FRC alone, with a significant reduction seen at TLC alone. The continued efficacy of Respreeza in slowing the progression of emphysema was demonstrated in a 2-year open-label extension of the RAPID trial. Although lung density loss was slowed when treatment was initiated later in the disease course, lung density loss prior to treatment was not recovered.