C1-Esterase Inhibitor (Recombinant) Injection
C1-esterase inhibitor (recombinant) is a lab-made protein that replaces a missing clotting-system regulator, used to treat acute hereditary angioedema attacks in adults and adolescents.
🧬 Where this information comes from
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Ruconest is a specialist, lab-made (recombinant) copy of C1-esterase inhibitor, the protein missing in hereditary angioedema (HAE), used at the first sign of an acute attack in adults and adolescents to shut down the overactive enzymes that make bradykinin, which causes the leaking and swelling. It is generally well tolerated, with headache, nausea or diarrhea the side effects most likely to show up. Watch for a serious allergic reaction (hives, chest tightness, wheezing, feeling faint), which can mimic an attack, and stop the injection and get emergency help if it happens. Blood clots are the other risk, mostly in people with clotting risk factors such as a past clot, an indwelling IV line or oral birth control.
Clinical pearls
- Ruconest is produced using rabbit-derived technology, so any known or suspected rabbit allergy rules it out.
- It was not proven to work for throat swelling, so a laryngeal attack still needs emergency care, not this medicine alone.
- A second dose is allowed if symptoms persist, but never more than two doses within any 24 hours.
- Home self-injection is fine after proper training, given slowly into a vein over about five minutes.
Patient Information Guide A plain-language walkthrough of C1-Esterase Inhibitor (Recombinant) Injection, written from its FDA label.
What C1-Esterase Inhibitor (Recombinant) Injection Is Used For
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C1-esterase inhibitor (recombinant) is approved for one specific, on-demand use:
- Ruconest (intravenous): Treatment of acute hereditary angioedema (HAE) attacks in adult and adolescent patients
- Ruconest limitation: Effectiveness was not established for HAE attacks affecting the larynx (throat) — do not rely on it as the primary treatment for laryngeal attacks
How C1-Esterase Inhibitor (Recombinant) Injection Works
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People with hereditary angioedema don't have enough working C1-esterase inhibitor (C1INH) — a protein that normally keeps two important systems in check: the complement system and the contact system. Without enough C1INH, these systems become overactive, producing a chemical called bradykinin that makes blood vessel walls leak fluid into surrounding tissue, causing the rapid, painful swelling of an HAE attack. Ruconest replaces the missing C1INH by directly blocking the key enzymes in this chain — including plasma kallikrein, factor XIIa, factor XIa, and activated C1s — to stop the swelling process.
C1-Esterase Inhibitor (Recombinant) Injection Dosage
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Ruconest is given as a slow intravenous (IV) injection over about 5 minutes — it is not a pill or a daily medication. It is used on-demand: you (or a trained caregiver) give it when an HAE attack begins.
- A second dose may be given if symptoms don't improve, but no more than two doses in any 24-hour period
- Patients properly trained by a healthcare professional may self-administer at home
- The dose is based on body weight — follow your prescriber's exact instructions
- There is no food restriction since it is given intravenously, not by mouth
Dosing details from the FDA-approved label
From the C1-Esterase Inhibitor (Recombinant) Injection prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
Reconstitute each vial (2100 U) by adding 14 mL sterile Water for Injection per vial to obtain a solution of 150 U per mL.
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION 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. 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 2.2 Preparation and Handling Store RUCONEST in the original carton and protect from light prior to reconstitution. Do not use after expiration date on the product vial label. Water for Injection is not included in the RUCONEST package. Use aseptic technique to reconstitute, mix the solution, and to combine the reconstituted solution from more than one vial ( see Reconstitution [ 2.3 ] and Administration [ 2.4 ]). Do not mix or administer RUCONEST with other medicinal products or solutions. Discard all partially used vials after treatment.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
C1-Esterase Inhibitor (Recombinant) Injection Side Effects
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Most people tolerate Ruconest well. The most commonly reported side effects in clinical trials were:
Common side effects
- Headache
- Nausea
- Diarrhea
- Back pain
- Sneezing
- Abdominal pain (reported after marketing)
- Rash (reported after marketing)
When to get medical help
- Get emergency help right away if you develop hives, chest tightness, wheezing, low blood pressure, or signs of anaphylaxis (severe allergic reaction) during or after the injection
- Tell your doctor immediately if you notice signs of a blood clot — such as sudden leg pain or swelling, chest pain, shortness of breath, or neurological symptoms — especially if you have known clotting risk factors
- Because allergic reaction symptoms can look like an HAE attack, seek medical help if you are unsure which is occurring
The most serious reaction reported in clinical trials was anaphylaxis (a severe allergic reaction) — seek emergency medical help immediately if you develop hives, chest tightness, wheezing, or low blood pressure during or after your injection.
C1-Esterase Inhibitor (Recombinant) Injection Warnings and Precautions
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- Severe allergic reactions / anaphylaxis: These can happen during or after the injection. Signs include hives, chest tightness, wheezing, low blood pressure, or full anaphylaxis. Because these symptoms can look like an HAE attack, be alert to the difference. Stop the injection and get emergency help if a severe reaction occurs.
- Blood clots (thromboembolic events): Serious clotting events in arteries and veins have been reported with plasma-derived C1-esterase inhibitor products in patients who had clotting risk factors. Risk factors include a history of blood clots, an indwelling venous catheter, use of oral contraceptives or certain androgens, morbid obesity, and immobility. Patients with these risk factors should be monitored during and after Ruconest use.
C1-Esterase Inhibitor (Recombinant) Injection Interactions
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The Ruconest label does not identify specific drug, food, or supplement interactions. However, there are important handling precautions to note:
- Do not mix Ruconest with other medications in the same syringe or infusion line — it must always be administered through a separate line
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before Taking C1-Esterase Inhibitor (Recombinant) Injection
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- Rabbit allergy: Do not use Ruconest if you have a known or suspected allergy to rabbits or rabbit-derived products — Ruconest is produced using recombinant rabbit technology
- Prior severe allergic reaction to C1-esterase inhibitor: Do not use if you have ever had a life-threatening allergic reaction (anaphylaxis) to any C1-esterase inhibitor preparation
- Blood clot risk factors: Tell your doctor if you have a history of thrombosis (blood clots), use an indwelling catheter, take oral contraceptives or certain androgens, have morbid obesity, or have limited mobility
- Pregnancy: Limited data from a small study did not show adverse outcomes, but there is not enough evidence to rule out all risk. Discuss the benefits and risks with your doctor
- Breastfeeding: No data exist on whether Ruconest passes into human milk. Talk to your doctor before using it while breastfeeding
- Adolescents (ages 13–17): Safety and efficacy have been evaluated in this age group; use in younger children is not established
- Older adults (65+): Only a small number of patients over 65 were included in clinical studies — too few to draw firm conclusions about whether they respond differently
What C1-Esterase Inhibitor (Recombinant) Injection Does in the Body
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Ruconest works by raising the level of functional C1-esterase inhibitor activity in the blood. People with HAE have low levels of a blood protein called C4 — a marker that reflects overactivation of the complement system. Ruconest restores C4 levels toward normal in a dose-dependent way, meaning higher doses produce a greater effect. A standard dose of 50 U/kg raises C1INH activity above the lower limit of normal (0.7 U/mL) in HAE patients.
How Your Body Processes C1-Esterase Inhibitor (Recombinant) Injection
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After a standard intravenous dose of 50 U/kg, Ruconest reaches peak C1INH activity in the blood in about 18–19 minutes, with an elimination half-life (the time it takes the body to clear half the drug) of roughly 2.5 hours. The drug is cleared from the body faster at lower doses than at higher doses — meaning clearance is nonlinear. Studies have not been conducted in special populations such as pediatric patients, older adults, or people with kidney or liver impairment.
How to Store C1-Esterase Inhibitor (Recombinant) Injection
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Store in the original package in order to protect from light. stored at 36ºF - 77ºF (2ºC - 25ºC). Do not freeze.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
C1-Esterase Inhibitor (Recombinant) Injection: Pharmacist Answers to Common Questions
Quick, plain-English answers to the questions patients ask most about C1-Esterase Inhibitor (Recombinant) Injection — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Ruconest and why has it been prescribed to me?
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How do I actually take it — is it a shot I give myself?
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What side effects should I expect, and when should I be worried?
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I'm allergic to rabbits — is that a problem?
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Can I use it if I'm pregnant or breastfeeding?
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Are there medicines I should avoid mixing with Ruconest?
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Is C1-Esterase Inhibitor (Recombinant) Injection available over the counter?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More About C1-Esterase Inhibitor (Recombinant) Injection on HelloPharmacist
C1-Esterase Inhibitor (Recombinant) Injection on the U.S. Market: Products, Makers and Brands
How C1-Esterase Inhibitor (Recombinant) Injection appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
The FDA lists C1-Esterase Inhibitor (Recombinant) Injection products. Brand names on the directory include Ruconest, Haegarda, Cinryze and 1 more; the rest are generics.
How Widely C1-Esterase Inhibitor (Recombinant) Injection Is Used (Medicaid Data)
A general measure of how commonly C1-Esterase Inhibitor (Recombinant) Injection is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely C1-Esterase Inhibitor (Recombinant) Injection is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is C1-Esterase Inhibitor (Recombinant) Injection prescribed? Of the 1,603 medications we measure, C1-Esterase Inhibitor (Recombinant) Injection ranks #1,400 by Medicaid prescriptions — more than 13% of them.
Utilization by C1-Esterase Inhibitor (Recombinant) Injection product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
C1 esterase inhibitor (recombinant) 2100 UNT Injection
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1599836
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of C1-Esterase Inhibitor (Recombinant) Injection, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 2 listed C1-Esterase Inhibitor (Recombinant) Injection NDCs with Medicaid activity.
C1-Esterase Inhibitor (Recombinant) Injection Side Effects Reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for C1-Esterase Inhibitor (Recombinant) Injection — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists C1-Esterase Inhibitor (Recombinant) Injection in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
C1-Esterase Inhibitor (Recombinant) Injection FDA Approval History
How C1-Esterase Inhibitor (Recombinant) Injection went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
C1-Esterase Inhibitor (Recombinant) Injection Recall History
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no C1-Esterase Inhibitor recalls since July 2021.
✅No C1-Esterase Inhibitor recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Oct 8, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 1599832 1 dose form · 4 strengths
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Dose form (SCDF) Injection RxCUI 1729335No current FDA listingClinical drug / strength (SCD) (human) 2000 UNTRxCUI 1926818(human) 3000 UNTRxCUI 1926825(human) 500 UNTRxCUI 1729336(recombinant) 2100 UNTRxCUI 1599836
Look up RxCUI 1599832 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
C1-Esterase Inhibitor (Recombinant) Injection Supply and Shortage Status
Whether C1-Esterase Inhibitor (Recombinant) Injection is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
C1-Esterase Inhibitor (Recombinant) Injection Brand Names
C1-Esterase Inhibitor (Recombinant) Injection is sold under 4 brand names in the FDA directory — Ruconest, Haegarda, Cinryze, Berinert. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
C1-Esterase Inhibitor (Recombinant) Injection Drug Class (RxNorm)
C1-Esterase Inhibitor (Recombinant) Injection belongs to the Human C1 Esterase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for This C1-Esterase Inhibitor (Recombinant) Injection Page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Pharming Healthcare Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →