Is zilucoplan FDA-approved, and what does the research show?

What is zilucoplan?

Zilucoplan is a prescription drug for one disease, generalized myasthenia gravis ². The paper on its main trial calls that condition "a chronic, unpredictable, and debilitating rare disease" ¹. The label's own scales measure it as muscle weakness and as loss of everyday functions ². The approved patients are those whose blood carries antibodies against the acetylcholine receptor ². Nerve endings release acetylcholine, which binds to receptors on the muscle ⁵.

The drug itself is, in the label's words, "a 15 amino-acid, synthetic macrocyclic peptide" ². Amino acids are the building blocks of proteins, and macrocyclic means the chain is closed into a ring. UCB, Inc. holds the FDA application, and the product is named Zilbrysq ³, ². It is injected under the skin, which the label calls subcutaneous use ².

Zilucoplan is not a wellness, weight-loss or performance peptide. The label names no use for weight, muscle building or aging ².

Is zilucoplan FDA-approved?

Yes, as a prescription drug for one use. FDA approved Zilbrysq (zilucoplan) on October 17, 2023, under application number NDA 216834 ³. Drugs@FDA lists its marketing status as "Prescription" as of November 9, 2026, the date of the record's data ³.

The label states one indication. Zilbrysq "is indicated for the treatment of generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive" ². Safety and effectiveness in children "have not been established" ².

The approval comes with a restriction. "Because of the risk of serious meningococcal infections," the October 2026 label says, the drug "is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) called ZILBRYSQ REMS" ². Its rules include "Prescribers must enroll in the REMS" and "Pharmacies that dispense ZILBRYSQ must be certified in the REMS and must verify prescribers are certified" ².

The label has been revised since approval. Drugs@FDA records a supplement, a change to an approved application, approved October 15, 2026 ³. The label revised that month lists recent changes only to its dosage and administration sections ². The April 2024 label and the October 2026 label word the indication identically ⁶, ².

See the FDA status of every peptide, updated weekly.

How does zilucoplan work?

Zilucoplan is a complement inhibitor ². Complement is a part of the immune system, a set of blood proteins that act in sequence. The label gives the target: zilucoplan "binds to the complement protein C5 and inhibits its cleavage to C5a and C5b" ². With C5 left whole, the final stage of the sequence cannot form ². The label calls that stage "the terminal complement complex, C5b-9" ².

How this helps in myasthenia gravis is not settled. The label says the precise mechanism "is unknown but is presumed to involve reduction of C5b-9 deposition at the neuromuscular junction," the point where a nerve meets a muscle ², ⁵.

The blocking itself was measured in patients ². In the approval trial, complement inhibition of 97.5 percent was seen by the end of the first week and held through 12 weeks ². In an earlier phase 2 study, a mid-stage trial, inhibition reached 89.1 percent within 3 hours of the first injection, at the higher of two doses tested ². The drug's mean half-life in blood, the time for half of it to clear, was about 172 hours, or 7 to 8 days ².

The same action explains the main risk. The label says the drug "blocks terminal complement activation; therefore, patients may have increased susceptibility to infections, especially with encapsulated bacteria," a group that includes the meningococcus ². Its warnings speak of complement inhibitors as a class ². Pegcetacoplan, which has its own page here, is another complement inhibitor ⁷.

What does the research show?

Approved by FDA for generalized myasthenia gravis on one trial, called RAISE in its paper and Study 1 in the label ¹, ². It was randomized, double-blind and placebo-controlled ¹. Patients were assigned by chance to zilucoplan or a dummy injection, and neither they nor their doctors knew which ¹. It ran for 12 weeks at 75 sites in Europe, Japan and North America, and UCB Pharma funded it ¹.

The trial enrolled adults aged 18 to 74 with antibody-positive generalized myasthenia gravis ¹. Entry required disease graded class II to IV on the Myasthenia Gravis Foundation of America scale ¹. Classes II to IV on that five-class scale run from mild to severe weakness in muscles other than those of the eyes.

The Myasthenia Gravis Activities of Daily Living (MG-ADL) scale rates eight daily functions from 0 to 3 each, for a total of 0 to 24, and higher is worse ². The Quantitative Myasthenia Gravis (QMG) score grades muscle weakness on 13 items, for a total of 0 to 39 ². Entry also required at least 6 on the MG-ADL and at least 12 on the QMG ¹.

Of 239 patients screened, 174 were randomized: 86 to zilucoplan and 88 to placebo ¹. Each injected the study drug under the skin once a day ¹. The mean starting MG-ADL score was 10.6 ².

Patients already on other treatment kept it at a stable dose ². About 85 percent in each group took cholinesterase inhibitors, 63 percent took steroids and 51 percent took other immune-suppressing drugs ². Cholinesterase inhibitors are drugs that slow the breakdown of acetylcholine, the chemical a nerve uses to signal a muscle.

After 12 weeks, the MG-ADL score had fallen by 4.39 points in the zilucoplan group and by 2.30 in the placebo group ¹, ². The difference was 2.09 points in zilucoplan's favor ¹. Its 95 percent confidence interval, the range the true difference probably lies in, ran from 0.95 to 3.24 ¹. The paper gives p=0.0004, meaning a gap this size would rarely arise by chance ¹. The QMG score fell by 6.19 points with zilucoplan and by 3.25 with placebo, a difference of 2.94 ².

The label also counts responders at week 12, without rescue therapy ². In the zilucoplan group, 73.1 percent improved by at least 3 MG-ADL points, against 46.1 percent on placebo ². On the QMG, 58 percent improved by at least 5 points, against 33 percent on placebo ².

The placebo comparison lasted 12 weeks ². Across the myasthenia gravis studies, 212 patients were treated at 0.3 mg/kg, 137 for at least 6 months and 87 for at least a year ². Patients who finished the trials could join an open-label extension, in which every patient takes zilucoplan ⁸. The label reports safety findings from the extension studies and no efficacy figures ². In the extension's interim report, patients first given zilucoplan kept a 6.04-point fall in MG-ADL score through week 60 ⁸.

Studied in people with ALS, which its trial paper calls "a fatal neurodegenerative disease": a randomized, double-blind, placebo-controlled platform trial, published online February 3, 2025 ⁴. A platform trial tests several drugs at once and shares placebo data between them ⁴. It randomized 162 participants, 122 to zilucoplan and 40 to its own placebo, for a planned 24 weeks ⁴. The zilucoplan group was compared with a shared placebo group of 164 ⁴.

The measure was a disease rate ratio combining a function score and survival, where a value below 1 would indicate benefit ⁴. The estimate was 1.08, with a 95 percent credible interval of 0.87 to 1.31 ⁴. A credible interval is the range that, under the trial's statistical model, holds the true value with 95 percent probability. The trial "was stopped early for futility," and the authors concluded that "treatment did not alter disease progression" ⁴.

Some things have not been studied. The label says its studies "did not include sufficient numbers of patients aged 65 and older" to show whether they respond differently ². No clinical drug-interaction studies have been performed, and no studies of cancer-causing potential have been conducted ². Neither the label nor the published summary of either trial reports a change in body weight ¹, ², ⁴. A PubMed search on November 10, 2026, for clinical-trial records with zilucoplan in the title returned eight, none on weight, muscle building, aging or performance.

What are the side effects?

The October 2026 label opens with a boxed warning, set in a box above everything else ². It reads: "ZILBRYSQ, a complement inhibitor, increases the risk of serious infections caused by Neisseria meningitidis" ². That bacterium, the meningococcus, causes infections the label names as "septicemia and/or meningitis" ². Septicemia is an infection of the blood, and meningitis is an infection of the lining of the brain.

The warning continues: "Life-threatening and fatal meningococcal infections have occurred in patients treated with complement inhibitors" ². Such infections "may become rapidly life-threatening or fatal if not recognized and treated early" ².

The warning's instruction to prescribers reads: "Complete or update vaccination for meningococcal bacteria (for serogroups A, C, W, Y, and B) at least 2 weeks prior to the first dose of ZILBRYSQ, unless the risks of delaying therapy outweigh the risk of developing a serious infection" ². The label adds that patients "are at increased risk for invasive disease caused by Neisseria meningitidis, even if they develop antibodies following vaccination" ².

The label tells patients to seek immediate medical care for signs of infection ². Its list includes "fever and a rash," "headache with a stiff neck or stiff back," "confusion" and "eyes sensitive to light" ². Under the REMS, patients are told to carry a Patient Safety Card "at all times during and for 2 months following treatment discontinuation" ².

The October 2026 label has one contraindication, a situation in which the drug must not be started ². Zilbrysq "is contraindicated for initiation in patients with unresolved serious Neisseria meningitidis infection" ². The label also warns of other infections, naming Streptococcus pneumoniae, Haemophilus influenzae and Neisseria gonorrhoeae, the bacterium of gonorrhea ². Its instruction is to "Use caution when administering ZILBRYSQ to patients with any other systemic infection" ².

A second warning concerns the pancreas. Pancreatitis, an inflammation of the pancreas, and pancreatic cysts "have been reported in patients treated with ZILBRYSQ" ². In the open-label extension studies, 7 patients (3.3 percent) had pancreatic events: 4 had pancreatitis and 3 had cysts ². The label says to "Discontinue ZILBRYSQ in patients with suspected pancreatitis" until it is ruled out or has resolved ².

In the 12-week trial, a raised level of lipase, a pancreatic enzyme measured in blood, was reported in 6 zilucoplan patients (6.9 percent) and in none on placebo ². Raised amylase, a second such enzyme, was reported in 4 zilucoplan patients (4.7 percent) and 1 placebo patient (1.1 percent) ².

The common reactions come from the same trial, with 86 patients on zilucoplan and 88 on placebo ². Injection site reactions were reported in 29 percent of the zilucoplan group and 16 percent of the placebo group ². Upper respiratory tract infections were reported in 14 and 7 percent, and diarrhea in 11 and 2 percent ². Urinary tract infection was reported in 8 and 5 percent, and nausea or vomiting in 8 and 7 percent ².

The trial paper counts adverse events of any kind in 66 zilucoplan patients (77 percent) and 62 placebo patients (70 percent) ¹. Serious events and serious infections were similar in the two groups ¹. One patient died in each group, of COVID-19 on zilucoplan and of a brain hemorrhage on placebo ¹. Neither death was considered related to the study drug ¹.

Longer use has shown one more reaction. Morphea, a form of localized scleroderma that NIH calls "patches of scleroderma," was seen in 10 of 213 patients (5 percent) in the open-label extension studies, by the label's count ², ⁹. Most cases began more than a year into treatment and were mild to moderate, and one patient stopped the drug because of it ².

The ALS trial compared zilucoplan with placebo in a different group of patients, for a planned 24 weeks ⁴. Its authors wrote that "No unexpected treatment-related risks were identified" ⁴.

There are no data on use in pregnant women ². In pregnant monkeys, zilucoplan increased embryofetal death at exposures similar to those in people, and the label's summary is "Based on animal data, may cause fetal harm" ². In male monkeys it depleted the sperm-forming cells of the testes, and the loss had not reversed after an 8-week recovery period ².

In sport

Zilucoplan is not named on WADA's 2026 Prohibited List ¹⁰. WADA, the World Anti-Doping Agency, lists peptide hormones, growth factors, related substances and mimetics in section S2, and zilucoplan is not among them ¹⁰. No section of the list names complement inhibitors as a class ¹⁰.

What JumpstartMD offers

JumpstartMD does not prescribe zilucoplan. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.