Population pharmacokinetics of plasma-derived C1 esterase inhibitor concentrate used to treat acute hereditary angioedema attacks.

BACKGROUND: C1 esterase inhibitor (C1-INH) replacement is recommended as a first-line therapy for acute edema attacks in hereditary angioedema (HAE). Only limited pharmacokinetic analyses of the administered C1-INH in plasma are available. OBJECTIVE: To investigate retrospectively the population pharmacokinetics of a plasma-derived C1-INH (pC1-INH) concentrate used to treat acute HAE attacks in a randomized, placebo-controlled phase 2/3 study in patients with HAE. METHODS: Acute abdominal and facial attacks were treated with either a pC1-INH concentrate (Berinert) at single intravenous doses of 10 or 20 U/kg body weight or placebo. Plasma sampling was conducted 0, 1, and 4 hours after dosing. A nonlinear retrospective population pharmacokinetic model was obtained using the assumption of a 1-compartment model. RESULTS: The final population pharmacokinetic model was based on data from 97 patients treated with 10 or 20 U/kg of pC1-INH concentrate. The estimated mean half-life was 32.7 hours (90% confidence interval, 16.6-48.8 hours), and the estimated mean clearance was 0.92 mL/kg/h (90% confidence interval, 0.50-1.33 mL/kg/h). CONCLUSIONS: The half-life of the same pC1-INH concentrate reported in a previous study was confirmed by this retrospective population pharmacokinetic analysis in patients treated for acute HAE attacks. In contrast to other treatment options with shorter half-lives, the long half-life of pC1-INH concentrate may provide an extended period of protection, even after the symptoms of an attack have subsided.

Phase I comparability of recombinant human albumin and human serum albumin.

Recombinant human albumin (rHA) is a highly purified animal-, virus-, and prion-free product developed as an alternative to human serum albumin (HSA), to which it is structurally equivalent. The present investigation compared the safety, tolerability, and pharmacokinetics/pharmacodynamics of rHA with HSA. Two double-blind, randomized trials were performed in healthy volunteers using intramuscular (IM) and intravenous (IV) administration. The IM trial included 500 volunteers, each receiving 5 repeat doses of 5 mg (100 subjects), 15 mg (100 subjects), or 65 mg (300 subjects) of rHA or HSA. Thirty volunteers participated in the IV trial, each receiving ascending doses (10 g, 20 g, and 50 g) of either rHA or HSA. In both trials, all adverse events were recorded and conventionally classified; potential allergic responses were also monitored. Blood samples were taken in both studies to test for IgG or IgE antibodies against test products and potential impurities. For the IV study, pharmacokinetic/pharmacodynamic assessments were performed, including measurement of serum albumin, colloid osmotic pressure, and hematocrit pre- and postinfusion. Nine subjects in the IM study (4 recipients of rHA and 5 of HSA) reported drug-related, potentially allergic events; all but 2 of these were skin related. No serious or potentially allergic events were reported with either product in the IV study. There was no immunological response to either product, and dose level did not influence the study outcomes. Serum albumin, colloid osmotic pressure changes, and hematocrit ratio were as expected, with no differences between rHA and HSA. rHA and HSA exhibited similar safety, tolerability, and pharmacokinetic/pharmacodynamic profiles, with no evidence of any immunological response.