Zilucoplan (Zilbrysq)_Dosage, benefits & legal status
Also known as Zilbrysq, RA101495, RA-101495, zilucoplan sodium
A 15-residue ring-shaped lipopeptide that stops complement attacking the nerve-muscle junction. Approved in 2023 and sold only through a safety programme.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Zilucoplan (Zilbrysq)?
Plain language first. The technical label stays, but it never stands alone.Overview
In generalised myasthenia gravis, antibodies attack the receptors nerves use to switch muscles on, and complement does much of the damage. In the 174-person RAISE trial, a daily injection improved the daily-activities score by 4.39 points against 2.30 on placebo over 12 weeks. Like every C5 blocker, it raises the risk of meningococcal infection, so vaccination comes first.
Zilucoplan is a 15-residue macrocyclic peptide, closed by a lactam bridge between residues 1 and 6, with four non-natural amino acids and a palmitic acid tail on a 24-unit PEG linker at its last lysine. It binds complement protein C5 at about 0.43 nanomolar, so C5 cannot be cut into C5a and C5b, and it also stops any C5b that forms from joining C6. Ra Pharmaceuticals discovered it; UCB bought Ra Pharma in April 2020.
What it's used for
A prescription daily self-injection for generalised myasthenia gravis in adults who test positive for acetylcholine receptor antibodies.
How does Zilucoplan (Zilbrysq) work?
What it does in the body, and where.Zilucoplan stops complement, part of the innate immune system, from punching holes in the muscle membrane at the nerve-muscle junction.
- 01The damageIn acetylcholine receptor antibody myasthenia gravis, antibodies stuck to the muscle side of the junction switch on complement. Its end product, the membrane attack complex (C5b-9), damages the receptor-rich membrane, so nerve signals get through less well.
- 02Two blocks on C5Zilucoplan binds C5 at a site away from where eculizumab binds, so C5 cannot be cut into C5a and C5b. It also stops any C5b that forms from joining C6. Complement activity fell 97.5% within a week in RAISE, though the label says the exact mechanism in myasthenia gravis is unknown.
- 03Why a daily jab worksThe palmitic acid tail and PEG linker stretch the half-life to about 7 days, so a small daily injection keeps levels steady. At about 3.6 kDa it is roughly a fortieth the size of an antibody such as eculizumab (about 148 kDa).
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Phase 3 RAISE
FDA-approved- Human trialMG-ADL fell 4.39 points against 2.30 at 12 weeks, and QMG 6.19 against 3.25.
- Human trial73.1% against 46.1% improved by 3 or more MG-ADL points without rescue treatment.
- No dataMinimal symptom expression was not significantly different (14.0% against 5.8%, p=0.0885).
Long-term use
FDA-approved- Human trialIn RAISE-XT, about 6 points of MG-ADL improvement from baseline held to week 60.
Long-term safety
FDA-approved- No dataIn the open-label extensions, morphoea appeared in 10 of 213 people, mostly after a year, and pancreatitis or pancreatic cysts in 3.3%.
ALS
tested-and-failed- Human trialHEALEY platform trial, 162 people: stopped for futility, with no slowing of decline (disease rate ratio 1.08).
Japan approved it before the US: 25 September 2023, against 17 October 2023. The boxed warning covers meningococcal infection only; pancreatitis and morphoea sit elsewhere in the label, and the UK and EU labels list enzyme rises rather than pancreatitis itself. Injection-site reaction rates are quoted as 29%, 26.7% or 16% (bruising alone) depending on how terms are grouped. The phase 2 met its primary endpoint only against a lenient one-sided alpha of 0.10 (QMG p=0.05, MG-ADL p=0.04, both one-sided), so calling it positive needs that context. It has 15 residues, not the 110 one peptide wiki lists. 3,562 Da is the free acid; the marketed tetrasodium salt is 3,650 Da. Vaccination lowers the meningococcal risk but does not remove it.
The published record
Papers and trials about Zilucoplan (Zilbrysq)
70 papers tagged human · 31 not reviews or lab · 8 clinical trial publications
19 registered trials · 12 with posted results
Furthest stage reached: Approved in the US
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about Zilucoplan (Zilbrysq)
Evidence
FDA-approved
Category
Immune support
Common vial
Varies
Half-life
About 172 hours (7 days)
How much, and do you cycle it?
The range, and whether you take breaks.16.6, 23 or 32.4 mg daily, by body weight (label), once daily. Continuous, open-ended FDA label
Taken every day for as long as it controls symptoms. Patients carry a safety card during treatment and for 2 months after the last dose.
How long does it stay in the body?
The half-life, and where the figure comes from.About 172 hours (7 days)FDA label
The label gives a mean of about 172 hours; single-dose studies in healthy volunteers gave 156 to 185. Peak 3 to 6 hours after injection; levels build about 3-fold over 2 weeks of daily dosing. More than 99% is bound to plasma proteins. Broken down by proteases; an active metabolite made by CYP4F2 lasts about 220 hours. Under 1% leaves in urine and faeces.
Source: Zilbrysq US prescribing information section 12.3; UK SmPC 5.2; TGA AusPAR
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.Zilucoplan (Zilbrysq) is not reconstituted
It is not supplied as a powder measured in milligrams, so there is no water-to-powder math and no draw to calculate here. Doses are written in mg, in a ready-filled syringe.
Typical dose: 16.6, 23 or 32.4 mg daily, by body weight (label)
One pre-filled syringe a day, chosen by actual body weight: 16.6 mg under 56 kg, 23 mg from 56 to under 77 kg, and 32.4 mg at 77 kg and over, close to the trial dose of 0.3 mg/kg. No titration. Meningococcal vaccination at least 2 weeks before the first dose, and lipase and amylase checked first. A missed dose is taken as soon as possible, never more than one a day. No dose change for kidney impairment or moderate liver impairment. Supplied ready to inject, so there is nothing to mix.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Zilucoplan (Zilbrysq) keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Solubility, computed: 60% charged residues, 33% hydrophobic. Water usually sufficient.
A first-pass rule from peptide manufacturers' guidance. It does not account for disulfide bridges, salt form or how the powder was dried, and it predicts what should be easy rather than what will happen in your vial.
Who should avoid it
- Unresolved serious meningococcal (Neisseria meningitidis) infection: treatment must not start
- No meningococcal vaccination (serogroups A, C, W, Y and B) at least 2 weeks before the first dose, unless delay is riskier and antibiotics are given meanwhile
- Pregnancy: in monkeys it increased fetal deaths at exposures similar to the top human dose, and there are no human data
- Pancreatitis: the US label asks for lipase and amylase before starting and says to stop if pancreatitis is suspected
Stop and get help
- Fever, headache with a stiff neck, sensitivity to light, a rash or confusion: possible meningococcal infection, an emergency even after vaccination
- Severe upper abdominal pain spreading to the back, with nausea or vomiting: possible pancreatitis
Common effects
- Injection-site reactions in 29% against 16% on placebo
- Upper respiratory tract infection in 14% against 7%, and diarrhoea in 11% against 2%
- Raised lipase in 7% against 0% and raised amylase in 5% against 1%; in long-term use, 3.3% had pancreatitis or pancreatic cysts
- Morphoea (patches of hardened skin) in 5% in the long-term extensions, mostly after more than a year
- Urinary tract infection in 8% against 5%
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Zilucoplan (Zilbrysq) approved?
And where the numbers on this page come from.Yes. Zilucoplan (Zilbrysq) is FDA approved and available on prescription in the United States. It is also approved in Japan, the European Union, the United Kingdom, Canada, and Australia.
- Approval statusFDA-approved
- RouteUnder the skin (subcutaneous)
- Checked14 October 2026
- Approved outside the USJapan, European Union, United Kingdom, Canada, Australia: Japan 25 September 2023 (first worldwide, after steroids or immunosuppressants fail), EU 1 December 2023 and Great Britain 15 January 2024 as add-on therapy, Canada 11 July 2024 and Australia 31 July 2024. Also approved in the US.This does not change the United States position above.
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesZilbrysq US prescribing information (1/2026)Drugs@FDA, NDA 216834EMA, Zilbrysq EPAREMA, Zilbrysq public assessment reportFDA GSRS substance record, zilucoplan (UNII YG391PK0CC)Howard JF Jr et al., Lancet Neurology 2023;22:395-406 (RAISE)ClinicalTrials.gov, RAISE posted results (NCT04115293)Howard JF Jr et al., JAMA Neurology 2020;77:582-592 (phase 2)Howard JF et al., Therapeutic Advances in Neurological Disorders 2024 (RAISE-XT)UCB, approval in Japan (25 Sep 2023)TGA, Australian public assessment reportUK summary of product characteristics (emc)Tang GQ et al., Frontiers in Immunology 2023;14:1213920Paganoni S et al., JAMA Network Open 2025 (HEALEY ALS, regimen A)ClinicalTrials.gov, IMNM posted results (NCT04025632)De Leeuw E et al., Respiratory Research 2022;23:202 (ZILU-COV)UCB completes acquisition of Ra Pharmaceuticals (SEC exhibit, Apr 2020)
What has happened recently
Japan approved it first, on 25 September 2023, for adults whose disease is not controlled by steroids or other immunosuppressants. The FDA approved it on 17 October 2023 (NDA 216834, orphan drug) for adults with generalised myasthenia gravis who are acetylcholine receptor antibody positive, with a boxed warning for meningococcal infection; it is available only through the ZILBRYSQ REMS, a programme that checks vaccination. The EU authorised it on 1 December 2023 as an add-on to standard therapy, followed by Great Britain (15 January 2024), Canada (11 July 2024) and Australia (31 July 2024). The EU medicines committee backed a pre-filled pen in March 2026; the US product is a pre-filled syringe. UCB holds it after buying Ra Pharmaceuticals in April 2020 at $48 a share. No generic exists.
You can compare this against the whole library, or read how to check a seller.
What else is like Zilucoplan (Zilbrysq)?
Others in Immune support, side by side.If you're weighing Zilucoplan (Zilbrysq), it's worth reading Thymosin Alpha-1, Glutathione, and LL-37 in the same class.
A 15-residue ring-shaped lipopeptide that stops complement attacking the nerve-muscle junction. Approved in 2023 and sold only through a safety programme.
- Dose
- 16.6, 23 or 32.4 mg daily, by body weight (label)
- How often
- Once daily
A well-studied shot that tunes up the immune system.
- Dose
- 1.6 mg per dose
- How often
- 2x per week
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- Dose
- 250 up to 1000 mg per day
- How often
- Daily (oral)
A natural germ-fighting peptide for stubborn infections and wound healing.
- Dose
- 0.1 up to 0.5 mg per dose (start low, increase slowly)
- How often
- Daily, short courses
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- Zilbrysq US prescribing information (1/2026)(2026)Weight-band doses; boxed meningococcal warning and REMS; injection-site reactions 29% against 16%; pancreatic events 3.3%; morphoea 5%; half-life 172 hours; embryofetal deaths in monkeys.
- Drugs@FDA, NDA 216834(2026)Approved 17 October 2023 as a new molecular entity with orphan status.
- EMA, Zilbrysq EPAR(2026)EU authorisation 1 December 2023 as add-on therapy; orphan designation withdrawn at authorisation.
- EMA, Zilbrysq public assessment report(2023)Full residue list, including N-methyl-aspartate at position 7; tetrasodium salt weight 3,650 Da.
- FDA GSRS substance record, zilucoplan (UNII YG391PK0CC)(2026)Recommended INN; CAS 1841136-73-9; 16 defined stereocentres.
- Howard JF Jr et al., Lancet Neurology 2023;22:395-406 (RAISE)(2023)174 adults: MG-ADL change -4.39 against -2.30 at 12 weeks (difference -2.09, p=0.0004); serious side effects 12.8% against 14.8%.
- ClinicalTrials.gov, RAISE posted results (NCT04115293)(2023)QMG -6.19 against -3.25; MG-ADL responders 73.1% against 46.1%; minimal symptom expression 14.0% against 5.8% (p=0.0885).
- Howard JF Jr et al., JAMA Neurology 2020;77:582-592 (phase 2)(2020)45 adults: placebo-corrected QMG -2.8 (one-sided p=0.05) and MG-ADL -2.3 (p=0.04), against a prespecified one-sided alpha of 0.10.
- Howard JF et al., Therapeutic Advances in Neurological Disorders 2024 (RAISE-XT)(2024)200 people in the open-label extension: MG-ADL about 6 points better than baseline at week 60.
- UCB, approval in Japan (25 Sep 2023)(2023)First approval worldwide, for adults inadequately controlled on steroids or immunosuppressants.
- TGA, Australian public assessment report(2025)Australian approval 31 July 2024; morphoea in 10 people, onset from day 430.
- UK summary of product characteristics (emc)(2026)Great Britain authorisation 15 January 2024; lipase and amylase rises listed, pancreatitis not listed as such.
- Tang GQ et al., Frontiers in Immunology 2023;14:1213920(2023)Binds human C5 at 0.43 nM; blocks C5 cleavage and C5b-C6 binding; four non-natural amino acids. UCB-funded lab study.
- Paganoni S et al., JAMA Network Open 2025 (HEALEY ALS, regimen A)(2025)162 randomised; stopped for futility; disease rate ratio 1.08.
- ClinicalTrials.gov, IMNM posted results (NCT04025632)(2022)Creatine kinase change -9.86% against -20.72% on placebo (p=0.464).
- De Leeuw E et al., Respiratory Research 2022;23:202 (ZILU-COV)(2022)COVID-19 with low oxygen: no significant gain in oxygenation or survival.
- UCB completes acquisition of Ra Pharmaceuticals (SEC exhibit, Apr 2020)(2020)Closed 2 April 2020 at $48 cash per share.
Beyond these, 107 records are indexed. Browse the records