C1 Esterase Inhibitor

• RUCONEST is a C1 esterase inhibitor [recombinant] indicated for the treatment of acute attacks in adult and adolescent patients with hereditary angioedema (HAE). Limitation of Use: Effectiveness was not established in HAE patients with laryngeal attacks.

• RUCONEST is contraindicated in patients with a history of allergy to rabbits or rabbit-derived products. RUCONEST is contraindicated in patients with a history of life-threatening immediate hypersensitivity reactions to C1 esterase inhibitor preparations, including anaphylaxis.contraindicated

For intravenous use after reconstitution only. For Intravenous Use Only. Reconstitute each vial (2100 U) by adding 14 mL sterile Water for Injection per vial to obtain a solution of 150 U per mL. ( 2.3 ) Administer the reconstituted solution at room temperature as a slow intravenous injection over approximately 5 minutes. ( 2.4 ) Appropriately trained patients may self-administer upon recognition of an HAE attack. ( 2.4 ) Recommended dose of RUCONEST for an acute attack Body weight RUCONEST Dose for Intravenous Injection Volume (mL) of Reconstituted Solution (150 U/mL) to be Administered < 84 kg 50 U per kg Body weight in kg divided by 3 ≥ 84 kg 4200 U (2 vials) 28 mL If the attack symptoms persist, an additional (second) dose can be administered at the recommended dose level. Do not exceed 4200 U per dose. No more than two doses should be administered within a 24-hour period. 2.1 Recommended Dosing Training on how to administer RUCONEST should be conducted by a qualified healthcare professional experienced in the treatment of HAE. Appropriately trained patients may self-administer upon recognition of an HAE attack. The recommended dose of RUCONEST is 50 U per kg with a maximum of 4200 U to be administered as a slow intravenous injection over approximately 5 minutes. If the attack symptoms persist, an additional (second) dose can be administered at the recommended dose level. Do not exceed 4200 U per dose. No more than two doses should be administered within a 24-hour period. Table 1.

Hypersensitivity reactions, including anaphylaxis may occur. Should symptoms occur, discontinue RUCONEST and administer appropriate treatment. ( 5.1 ) Serious arterial and venous thromboembolic (TE) events have been reported at the recommended dose of plasma derived C1 esterase inhibitor products in patients with risk factors. Monitor patients with known risk factors for TE events during and after RUCONEST administration. ( 5.2 ) 5.1 Hypersensitivity Severe hypersensitivity reactions may occur . The signs and symptoms of hypersensitivity reactions may include hives, generalized urticaria, tightness of the chest, wheezing, hypotension, and/or anaphylaxis during or after injection of RUCONEST. Should symptoms occur, discontinue RUCONEST and institute appropriate treatment. Because hypersensitivity reactions may have symptoms similar to HAE attacks, treatment methods should be carefully considered. [see Patient Counseling Information (17) ] 5.2 Thromboembolic Events Serious arterial and venous thromboembolic (TE) events have been reported at the recommended dose of plasma derived C1 esterase inhibitor products in patients with risk factors. Risk factors may include the presence of an indwelling venous catheter/access device, prior history of thrombosis, underlying atherosclerosis, use of oral contraceptives or certain androgens, morbid obesity, and immobility. Monitor patients with known risk factors for TE events during and after RUCONEST administration.

The serious adverse reaction in clinical studies of RUCONEST was anaphylaxis. The most common adverse reactions (≥ 2%) reported in all clinical trials were headache, nausea, and diarrhea. The serious adverse reaction reported in clinical trials was anaphylactic reaction. ( 6 ) The common adverse reactions (≥ 2%) reported in clinical trials were headache, nausea, and diarrhea. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Pharming Healthcare Inc. at 1-800-930-5221 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. The RUCONEST clinical development program evaluated a combined total of 940 administrations in 236 subjects (symptomatic and non-symptomatic). In clinical studies, a total of 205 symptomatic HAE patients received treatment with RUCONEST for a combined total of 650 acute angioedema attacks. Among these HAE patients, 83 were treated for a single HAE attack and 122 were treated for multiple attacks. Three randomized, placebo-controlled clinical trials (RCTs) were conducted in which 137 patients experiencing acute HAE attacks received RUCONEST (either an initial 50 U/kg or 100 U/kg body weight dose) or placebo (saline solution). Table 2 shows all adverse reactions (ARs) in the RCTs, compared with the placebo group. Table 2.

8.1 Pregnancy Risk Summary There are no adequate and well-controlled studies of RUCONEST in pregnant women. In the U.S. general population, regardless of drug exposure, available data suggest that major birth defects occur in 2 to 4% of the general population and miscarriage occurs in 15 to 20% of clinically recognized pregnancies. Data Human Data Limited available postmarketing safety data with RUCONEST use in pregnant women do not indicate any adverse effects in this population. In a retrospective case collection study, 14 pregnant women aged 17 to 37 years with HAE received RUCONEST at 50 U/kg (max 4200 U) via intravenous administration for treatment of acute atttacks or for prophylaxis during pregnancy. For all 14 women in this study, delivery at full term with the births of healthy babies occurred without complications. No adverse events related to RUCONEST treatment were reported during the pregnancy period. 1,2 However these data cannot definitely establish the absence of any risk because of the small sample size and non-randomized study design. Animal Data Embryo toxicity with 625 U/kg of RUCONEST (12.5 times the human dose) was tested after intravenous dosing of pregnant rats in a segment II (embryofetal toxicity) study design. There were no significant outcomes from this study.

1. 1Hereditary Angioedema97616%
2. 2Intentional Product Use Issue73612%
3. 3Drug Ineffective For Unapproved Indication5108.5%
4. 4Drug Ineffective4307.2%
5. 5Condition Aggravated4096.8%
6. 6Product Use In Unapproved Indication3896.5%
7. 7Pharyngeal Swelling3606.0%
8. 8Weight Decreased2404.0%
9. 9Product Dose Omission Issue2263.8%
10. 10Weight Increased2183.6%
11. 11Vascular Access Site Complication1793.0%
12. 12Maternal Exposure During Pregnancy1552.6%
13. 13Weight Fluctuation1542.6%
14. 14Underdose1522.5%
15. 15Covid-191492.5%

Recent PubMed references pinned to C1 Esterase Inhibitor as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Acquired angioedema due to C1 inhibitor deficiency: real-world clinical characteristics and treatment outcomes.
  Frontiers in immunology · 2026 · Toprak İD, Erdem S, Korkmaz P, et al.
  PMID 42253962DOI 10.3389/fimmu.2026.1836363
• Angioedema due to acquired C1 inhibitor deficiency: patient experience, conceptual disease model, and assessment of patient-reported outcome measures.
  Frontiers in immunology · 2026 · de Lange M, Cohn DM, Gobert D, et al.
  PMID 42220494DOI 10.3389/fimmu.2026.1810851
• Characterization of a unique pathogenic variant in the SERPING1 gene of a patient with hereditary angioedema type I.
  Journal of dermatological science · 2026 · Hisamoto T, Sentoku K, Shimomura Y, et al.
  PMID 41850960DOI 10.1016/j.jdermsci.2026.03.005
• Impact of C1-Inhibitor on Renal Function and Safety Outcomes in Kidney Transplant Recipients: A Meta-Analysis of Randomized Controlled Trials.
  Clinical transplantation · 2026 · Feng X, Zhang D, Qiu Y, et al.
  PMID 41674123DOI 10.1111/ctr.70479
• Novel SERPING1 Genetic Variant in Two Family Members with Hereditary Angioedema.
  Acta medica portuguesa · 2026 · Cosme Ferreira S, Rosa A, Sousa F, et al.
  PMID 41662830DOI 10.20344/amp.24214
• Type II hereditary angioedema with an apparently de novo SERPING1 mutation in China: A case report and family screening.
  Medicine · 2026 · Guan Z, Cai L, Li Y, et al.
  PMID 41560114DOI 10.1097/MD.0000000000047283
• Multiomics Mendelian randomization identifies serpin family G member 1 as a chronic obstructive pulmonary disease modulator.
  Signal transduction and targeted therapy · 2026 · Yi E, Cui J, Wang H, et al.
  PMID 41559025DOI 10.1038/s41392-025-02547-7
• Therapeutic Potential of C1-Inhibitor in Vascular Diseases and Beyond.
  Arteriosclerosis, thrombosis, and vascular biology · 2026 · Sundler Björkman L, Eswaran H, Grover SP, et al.
  PMID 41410053DOI 10.1161/ATVBAHA.125.323743

The 10 most recently updated of 94 ClinicalTrials.gov registrations naming C1 Esterase Inhibitor as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Study of IV Human Plasma-derived C1 Esterase Inhibitor Concentrate in Patients With Congenital C1-INH Deficiency for Treatment and Pre-procedure Preventing of Acute Hereditary Angioedema Attacks
  Recruiting · Phase 3 · Interventional · 124 enrolled · Octapharma
  NCT06361537updated 2026-06-09
• A Study to Learn About the C1-Inhibitor Function as Diagnosis for Hereditary Angioedema
  Recruiting · Interventional · 514 enrolled · Takeda
  NCT07293364updated 2026-05-19
• An Extension Study of Donidalorsen (IONIS-PKK-LRx) in Participants With Hereditary Angioedema
  Completed · Phase 2 · Interventional · 20 enrolled · Ionis Pharmaceuticals, Inc.
  NCT04307381updated 2026-05-08
• Study of Oral Deucrictibant XR Tablet for Prophylaxis and Deucrictibant IR Capsule for On-Demand Treatment of Angioedema Attacks in Adults With Acquired Angioedema Due to C1 Inhibitor Deficiency
  Recruiting · Phase 3 · Interventional · 32 enrolled · Pharvaris Netherlands B.V.
  NCT07266805updated 2026-05-07
• Recombinant Human C1 Esterase Inhibitor (Conestat Alfa) in the Prevention of Acute Ischemic Cerebral and Renal Events After Transcatheter Aortic Valve Implantation
  Completed · Phase 2 · Interventional · 141 enrolled · University Hospital, Basel, Switzerland
  NCT05145283updated 2026-04-22
• Complement and Graft-versus-host Disease
  Completed · Interventional · 70 enrolled · Assistance Publique - Hôpitaux de Paris
  NCT01520623updated 2026-03-05
• Improving Deceased-Donor Kidney Transplant Outcomes Via a Single Intragraft Injection of C1 Esterase Inhibitor (IMPROVE TRIAL)
  Recruiting · Phase 2 · Interventional · 180 enrolled · National Institute of Allergy and Infectious Diseases (NIAID)
  NCT06919003updated 2026-02-27
• Dose-ranging Study of Oral PHA-022121 for Acute Treatment of Angioedema Attacks in Patients With Hereditary Angioedema
  Completed · Phase 2 · Interventional · 74 enrolled · Pharvaris Netherlands B.V.
  NCT04618211updated 2025-12-17
• Study to Evaluate the Benefit of RUCONEST in Improving Neurological Symptoms in Post COVID-19 Infection
  Completed · Phase 2 · Interventional · 40 enrolled · IMMUNOe Research Centers
  NCT04705831updated 2025-08-11
• Dose-ranging Study of Oral PHA-022121 for Prophylaxis Against Angioedema Attacks in Patients With Hereditary Angioedema Type I or Type II
  Completed · Phase 2 · Interventional · 34 enrolled · Pharvaris Netherlands B.V.
  NCT05047185updated 2025-07-30

Frequently asked questions

What is C1 Esterase Inhibitor used for?

According to FDA labeling, C1 Esterase Inhibitor carries indications including: RUCONEST is a C1 esterase inhibitor [recombinant] indicated for the treatment of acute attacks in adult and adolescent patients with hereditary angioedema (HAE). Limitation of Use: Effectiveness was not established in HAE patients with laryngeal attacks.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What are the brand names for C1 Esterase Inhibitor?

C1 Esterase Inhibitor is marketed under brand names including Berinert, Cinryze, Haegarda, Ruconest.

What are the contraindications for C1 Esterase Inhibitor?

C1 Esterase Inhibitor labeling lists contraindications including: RUCONEST is contraindicated in patients with a history of allergy to rabbits or rabbit-derived products. RUCONEST is contraindicated in patients with a history of life-threatening immediate hypersensitivity reactions to C1 esterase inhibitor preparations, including anaphylaxis.. Always consult the full prescribing information and a clinician.