A Study to Assess Safety and PK of Liquid Alpha₁-Proteinase Inhibitor (Human) in Treating Alpha₁-Antitrypsin Deficiency

Inclusion Criteria: * Be between 18 and 70 years of age, inclusive * Had a diagnosis of congenital AATD * Had a documented total alpha₁-PI level \< 11 µM. If the total alpha₁-PI level had yet to be documented, a blood draw for total alpha₁-PI level was obtained at the Screening Visit * Had a post-bronchodilator Forced expiratory volume in 1 second (FEV1) ≥ 30% and \< 80% of predicted and FEV1/forced vital capacity (FVC) \< 70% * If the subject had received alpha₁-PI augmentation therapy of any kind, he/she must have been be willing to discontinue that treatment at the Week 1 (Baseline) Visit and remain off any kind of alpha₁-PI treatment, other than the investigational products for this study, while participating in the study Exclusion Criteria: * Subject had a moderate or severe pulmonary exacerbation during the 4 weeks before the Week 1 (Baseline) Visit * History of lung or liver transplant * Any lung surgery during the past 2 years (excluding lung biopsy) * Liver cirrhosis confirmed by biopsy * Elevated liver enzymes (aspartate transaminase \[AST\], alanine aminotransferase \[ALT\], and alkaline phosphatase \[ALP\]) equal to or greater than 2.5 times the upper limit of normal * Severe concomitant disease (e.g., congestive heart failure, clinically significant pulmonary fibrosis, malignant disease \[with the exception of skin cancers other than melanoma\], history of acute hypersensitivity pneumonitis reaction, or current chronic hypersensitivity pneumonitis) * Females who were pregnant, breastfeeding or, if of child-bearing potential, unwilling to practice a highly effective method of contraception (oral, injectable or implanted hormonal methods of contraception, placement of an intrauterine device (IUD) or intrauterine system (IUS), condom or occlusive cap with spermicidal foam/gel/film/cream/suppository, male sterilization, or abstinence) throughout the study * Known previous infection with or clinical signs and symptoms consistent with current hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV) infection * Smoking during the past 6 months or a positive urine cotinine test at the Screening Visit that is due to smoking * Participation in another investigational drug study within one month prior to the Week 1 (Baseline) Visit * History of anaphylaxis or severe systemic response to any plasma-derived alpha1-PI preparation or other blood product(s) * Use of systemic steroids above a stable dose equivalent to 5 mg/day prednisone (i.e.,10 mg every 2 days) within the 4 weeks prior to the Week 1 (Baseline) Visit inhaled steroids are not considered systemic steroids) * Use of systemic or aerosolized antibiotics for an exacerbation within the 4 weeks prior to the Week 1 (Baseline) Visit * Known selective or severe Immunoglobulin A (IgA) deficiency