Human C1-esterase inhibitor
Also known as: Berinert, C1-INH, Cinryze, Conestat alfa, Haegarda, Ruconest, SERPING1
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Summary
Human C1‑esterase inhibitor (C1‑INH) is a plasma‑derived or recombinant serpin used to treat hereditary angioedema (HAE), a rare disorder causing recurrent swelling of the skin, gastrointestinal tract, and airway. Approved formulations such as Berinert (plasma‑derived) and recombinant products are administered intravenously for on‑demand relief of acute attacks and, in some regimens, for short‑term prophylaxis.
Mechanism of Action
C1‑INH regulates the complement and contact systems by inhibiting serine proteases including C1r, C1s, plasma kallikrein, and activated factor XII. In HAE, deficient functional C1‑INH leads to unchecked kallikrein activity, excess bradykinin production, and increased vascular permeability. Replacement therapy restores protease inhibition, curtails bradykinin generation, and thereby reduces edema formation.
What the Research Shows
Randomised, double‑blind trials (IMPACT‑1) demonstrated that intravenous plasma‑derived C1‑INH at 20 U/kg produced symptom relief within a median of 0.5 hours, significantly faster than placebo. Extension data (IMPACT‑2) confirmed a median 30‑minute onset in real‑world use and reported improved quality‑of‑life scores with self‑administration. Recombinant C1‑INH, identical in sequence to the native protein, showed efficacy in three placebo‑controlled acute‑attack trials and two open‑label extensions, supporting a 50 U/kg IV dose. A pilot prophylaxis study indicated that weekly 50 U/kg recombinant C1‑INH for eight weeks reduced attack frequency without anti‑drug antibodies. Across studies, both products were well tolerated, with no confirmed viral transmission for plasma‑derived material.
Reported Benefits
Clinical trials consistently show rapid symptom relief for acute HAE attacks, with median onset times of 30–60 minutes. Intravenous administration enables treatment of life‑threatening laryngeal edema. Self‑administration at home improves health‑related quality of life. Recombinant C1‑INH offers a non‑plasma source, eliminating concerns about plasma‑derived contaminants, and has demonstrated prophylactic efficacy in reducing attack frequency.
Limitations of the Evidence
Evidence for prophylactic use is limited to a small pilot study; larger, long‑term trials are lacking. Most efficacy data pertain to intravenous dosing; subcutaneous formulations are not addressed in the cited abstracts. Comparative effectiveness versus other on‑demand agents (icatibant, ecallantide) is not provided. Real‑world data on rare adverse events remain sparse.
Safety Considerations
Both plasma‑derived and recombinant C1‑INH were reported as well tolerated in trial settings. No confirmed cases of viral transmission occurred with plasma‑derived product, and recombinant product did not induce anti‑drug antibodies. Reported adverse events were mild and comparable to placebo, but comprehensive safety profiling in broader populations is limited to the cited studies.
How It Is Administered
Human C1‑INH is supplied as a sterile concentrate for intravenous infusion. The plasma‑derived product is administered as a single IV bolus (e.g., 20 U/kg) for acute attacks. Recombinant C1‑INH is also given intravenously, typically 50 U/kg, and may be used weekly for prophylaxis in clinical study settings. Formulations are provided in vial form for reconstitution.
Routes of Administration
Goals & Uses
- Routine prophylaxis of HAE attacksPreventionHigh
- Pediatric HAE managementTreatmentModerate
- Pre-procedural prophylaxis of HAEPreventionHigh
- Acute treatment of HAE attacksTreatmentHigh
- Hereditary angioedema prophylaxis and acute treatmentIndicationHigh
- Capillary leak syndrome / sepsis-associated inflammationInvestigationalLow
Contraindications
- Uncontrolled disseminated intravascular coagulationCoagulationModerate
- Severe IgA deficiency with anti‑IgA antibodiesImmunologyModerate
- Known hypersensitivity to C1-INH preparationsAllergy / HypersensitivityHigh
- Hypersensitivity to C1-INH productAllergyHigh
- Rabbit allergy (Ruconest/Conestat alfa)AllergyHigh
- History of life-threatening thrombotic events (high-dose off-label use)Thrombotic RiskHigh
Adverse Effects
- Hypersensitivity / anaphylaxisImmunologicalRare
- HeadacheNeurologicCommonPain in the head or upper neck
- Injection/infusion site reactionsLocalCommon
- Thromboembolic eventsCardiovascularRare
- Hypersensitivity reactionImmunologicRare
- NauseaGastrointestinalUncommonFeeling of sickness or urge to vomit
- PyrexiaGeneralUncommon
- Injection site erythemaLocalCommonRedness at the injection site
- ThrombosisHematologicRareFormation of a blood clot
Drug Interactions
- Estrogen‑containing oral contraceptivesModerate
- Estrogen-containing oral contraceptivesModerate
- ACE inhibitorsModerate
- Tissue plasminogen activator (tPA)Low
- Antifibrinolytics (e.g., tranexamic acid)Low
Population Constraints
- Patients with high thrombosis riskCardiovascularRelative
- PregnancyReproductive SafetyRelative
- Pediatric patients <1 yearAgeRelative
- Pregnant womenReproductiveRelative
- Elderly (>75 years)GeriatricRelative
- Neonates / infants (off-label high-dose use)PediatricRelative
Regulatory Status
- European UnionApprovedApproved: Hereditary angioedema prophylaxis, Acute treatment of hereditary angioedemaApproved under EMA for plasma‑derived C1‑INH products.
- United StatesApprovedApproved: Hereditary angioedema prophylaxis, Acute treatment of hereditary angioedemaCinryze (SC), Berinert (IV), Haegarda (SC) approved.
- United KingdomApprovedApproved: Hereditary angioedema prophylaxis, Acute treatment of hereditary angioedemaApproved by MHRA.
FDA‑approved (Cinryze, Berinert, Haegarda); EMA‑approved; indicated for HAE types I and II.
Evidence & Sources
- Journal ArticleModerateKeating GM2009-01-01T00:00:00.000000Z
- Journal ArticleModerateRiedl M2015-01-01T00:00:00.000000Z
- Journal ArticleModerateCohn DM, et al.2025-01-01T00:00:00.000000Z
- Journal ArticleModerateCaballero T2021-01-01T00:00:00.000000Z
- Journal ArticleModerateHsu D, Shaker M2012-01-01T00:00:00.000000Z
Frequently Asked Questions
What triggers hereditary angioedema attacks?
HAE attacks are precipitated by factors that increase bradykinin production, such as trauma, stress, hormonal changes, or certain medications. The underlying deficiency of functional C1‑INH allows uncontrolled activation of the kallikrein‑kinin pathway, leading to swelling.
How quickly does C1‑INH relieve symptoms?
In randomized trials, intravenous C1‑INH reduced symptoms within a median of 30 to 60 minutes, with many patients experiencing relief as early as 15 minutes after infusion.
Can patients administer C1‑INH themselves?
Yes, both plasma‑derived and recombinant C1‑INH are approved for self‑administration via intravenous infusion, enabling patients to treat attacks at home and improve quality of life.
What are the common side effects of C1‑INH therapy?
Reported side effects are generally mild and include infusion‑related reactions such as headache, nausea, or transient fever. No serious adverse events or viral transmission have been confirmed in the cited studies.
Is C1‑INH used for long‑term prevention of attacks?
A pilot study showed that weekly intravenous recombinant C1‑INH reduced attack frequency, suggesting a prophylactic role, but larger trials are needed to establish routine long‑term use.
What is Human C1-esterase inhibitor?
Human C1‑esterase inhibitor (C1‑INH) is a plasma‑derived or recombinant serpin used to treat hereditary angioedema (HAE), a rare disorder causing recurrent swelling of the skin, gastrointestinal tract, and airway. Approved formulations such as Berinert (plasma‑derived) and recombinant products are administered intravenously for on‑demand relief of acute attacks and, in some regimens, for short‑term prophylaxis.
What is Human C1-esterase inhibitor used for?
Human C1-esterase inhibitor is educationally associated with: Routine prophylaxis of HAE attacks, Pediatric HAE management, Pre-procedural prophylaxis of HAE, Acute treatment of HAE attacks, Hereditary angioedema prophylaxis and acute treatment, Capillary leak syndrome / sepsis-associated inflammation. Educational only — not medical advice.
How is Human C1-esterase inhibitor administered?
Recorded routes of administration: Intravenous, Subcutaneous.
What are the potential side effects of Human C1-esterase inhibitor?
Reported adverse effects include: Hypersensitivity / anaphylaxis, Headache, Injection/infusion site reactions, Thromboembolic events, Hypersensitivity reaction, Nausea, Pyrexia, Injection site erythema, Thrombosis. This list is not exhaustive — consult a qualified clinician.
Who should avoid Human C1-esterase inhibitor?
Recorded contraindications: Uncontrolled disseminated intravascular coagulation, Severe IgA deficiency with anti‑IgA antibodies, Known hypersensitivity to C1-INH preparations, Hypersensitivity to C1-INH product, Rabbit allergy (Ruconest/Conestat alfa), History of life-threatening thrombotic events (high-dose off-label use). Consult a qualified clinician before use.