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Clinical Trial
. 2018 Oct;48(10):1325-1332.
doi: 10.1111/cea.13220. Epub 2018 Aug 26.

Population pharmacokinetics of subcutaneous C1-inhibitor for prevention of attacks in patients with hereditary angioedema

Dipti Pawaskar  1 , Michael A Tortorici  1 , Bruce Zuraw  2 , Timothy Craig  3 , Marco Cicardi  4 , Hilary Longhurst  5 , H Henry Li  6 , William R Lumry  7 , Inmaculada Martinez-Saguer  8 , Joshua Jacobs  9 , Jonathan A Bernstein  10 , Marc A Riedl  11 , Constance H Katelaris  12 , Paul K Keith  13 , Annette Feussner  14 , Jagdev Sidhu  15
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Free article
Clinical Trial

Population pharmacokinetics of subcutaneous C1-inhibitor for prevention of attacks in patients with hereditary angioedema

Dipti Pawaskar et al. Clin Exp Allergy. 2018 Oct.
Free article

Abstract

Background: Long-term prophylaxis with subcutaneous (SC) administration of a highly concentrated plasma-derived C1-esterase inhibitor (C1-INH) formulation was recently approved by the Food and Drug Administration for hereditary angioedema (HAE) attack prevention.

Objective: To characterize the population pharmacokinetics of C1-INH (SC) (HAEGARDA® ; CSL Behring) in healthy volunteers and HAE patients, and assess the variability and influence of covariates on pharmacokinetics.

Methods: C1-INH functional activity data obtained after administration of various C1-INH (intravenous; IV) and C1-INH (SC) doses from 1 study in healthy volunteers (n = 16) and 2 studies in subjects with HAE (n = 108) were pooled to develop a population pharmacokinetic model (NONMEM v7.2). Pharmacokinetic parameters derived from steady-state simulations based on the final model were also evaluated.

Results: C1-INH functional activity following C1-INH (SC) administration was described by a linear one-compartment model with first-order absorption and elimination, with inter-individual variability in all parameters tested. The mean population bioavailability of C1-INH (SC), and pharmacokinetic parameters for clearance (CL), volume of distribution, and absorption rate were estimated to be ~43%, 1.03 mL/hour/kg, 0.05 L/kg and 0.0146 hour-1 , respectively. The effect of bodyweight on CL of C1-INH functional activity was included in the final model, estimated to be 0.74. Steady-state simulations of C1-INH functional activity vs time profiles in 1000 virtual HAE patients revealed higher minimum functional activity (Ctrough ) levels after twice-weekly dosing with 40 IU/kg (~40%) and 60 IU/kg (~48%) compared with 1000 IU IV (~30%). Based on the population pharmacokinetic model, the median time to peak concentration was ~59 hours and the median apparent plasma half-life was ~69 hours.

Conclusions and clinical relevance: Twice-weekly bodyweight-adjusted dosing of C1-INH (SC) exhibits linear pharmacokinetics and dose-dependent increases in Ctrough levels at each dosing interval. In this analysis, SC dosing led to maintenance of higher Ctrough levels than IV dosing.

Keywords: angioedema; clinical immunology; prevention.

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