The study objective was to describe the pharmacokinetics (PK) of one or two doses of C1 esterase inhibitor (C1INH-nf) in hereditary angioedema (HAE) subjects who were not experiencing an HAE attack.

Inclusion Criteria:

• Enrolled in LEVP2005-1 (current or in the past)

Exclusion Criteria:

• C1 inhibitor infusion within the last 7 days
• Signs of any HAE attack
• HAE attack within 7 days before actual infusion of C1INH-nf
• Change in the dosage of androgens in the last 14 days before the study
• Use of antifibrinolytics in the last 7 days before the study
• Change in oral conceptive medication in the last two months before the study
• History of clinically relevant antibody development to C1 inhibitor
• Use of oral anticoagulant medication in the last 14 days
• Use of heparin within the last two days prior to the study
• History of allergic reaction to C1 inhibitor or other blood products
• Current participation (or within the past 90 days) in any investigational drug study other than those sponsored by Lev Pharmaceuticals
• Pregnancy or lactation
• B-cell malignancy
• Any clinically significant medical condition, such as renal failure, that in the opinion of the investigator would interfere with the subject's ability to participate in the study