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Evidence: HighPeptideDiscontinuedAntimicrobial peptide (indolicidin analogue)Topical gel · never approvedCatheter infection · rosacea

Omiganan

A 12-residue antimicrobial peptide built on bovine indolicidin: two catheter-infection phase 3 trials, two rosacea phase 3 trials, and no approval

Omiganan is a synthetic cationic peptide modelled on indolicidin, an antimicrobial peptide from cow neutrophils, and it was only ever developed as a topical gel. In the laboratory it killed a wide range of bacteria and yeasts, including resistant staphylococci. In the clinic it came close without succeeding: its second catheter trial, in 1,859 patients, missed its primary endpoint while reducing catheter colonisation, and of two rosacea phase 3 trials one met its endpoints and one did not. No regulator has approved it.

View Dosing Data Read Research →
Overview

What is it?

Omiganan is a 12-amino-acid analogue of indolicidin, a tryptophan-rich antimicrobial peptide from the granules of cow neutrophils. It carries five positive charges and four tryptophans, and like other cationic antimicrobial peptides it acts on microbial membranes: in vesicle models it bound negatively charged, bacteria-like membranes roughly an order of magnitude more strongly than neutral, mammalian-like ones. Against clinical isolates it killed gram-positive and gram-negative bacteria and yeasts, and resistance to methicillin, vancomycin or azoles barely changed its potency, at concentrations far below the 10,000 µg/mL in a 1% gel.

Its first use was to protect the skin around central venous catheters. Micrologix (later Migenix) and Fujisawa began a phase 3 trial against 10% povidone-iodine in September 2000 and completed it in February 2003: in 1,407 patients at 27 US centres it missed its primary endpoint, catheter-related bloodstream infection, while significantly reducing local catheter-site infections and catheter colonisation. Cadence Pharmaceuticals licensed the gel as Omigard in July 2004 and ran a confirmatory trial, CLIRS, in 1,859 patients from 2005 to 2008. Local catheter-site infection, now the primary endpoint, occurred in 6.3% on omiganan and 8.6% on povidone-iodine (P=0.082); microbiologically confirmed site infections (3.9% against 7.6%) and colonisation (43.7% against 55.1%) were significantly lower. Development for catheters ended in 2009.

Dermatology came next. Cutanea Life Sciences took the peptide into rosacea as CLS001 and, after two phase 2 studies, ran two phase 3 trials of a once-daily gel in severe papulopustular rosacea from 2015 to 2017, now listed under Maruho. In 463 patients the gel beat vehicle on both co-primary endpoints: inflammatory lesions fell by 18.1 against 13.5 (P=0.043), and 26.3% against 16.9% improved by two grades (P=0.019). In 263 patients it did not: lesions fell by 19.8 against 20.9, and 24.6% against 25.6% improved by two grades. A 307-patient open-label extension followed long-term safety. None of these phase 3 results has appeared as a paper in PubMed.

Later trials tested its effects on the skin microbiome and immune system. In atopic dermatitis it moved lesional skin bacteria towards those of healthy skin and cut cultured Staphylococcus aureus by 93.5%, but clinical scores did not improve in the larger 80-patient trial; it did not help facial seborrhoeic dermatitis, where ketoconazole did; and in genital warts it lowered human papillomavirus load without shrinking lesions. Studies in human cells and volunteers found that it amplifies interferon responses to toll-like receptor signals, one reason it was paired with imiquimod. Omiganan has never been approved: Drugs@FDA holds no application for it, and EMA's register of centrally authorised medicines has no entry.

1,859
CLIRS participants
catheter trial against povidone-iodine, 2005-2008
6.3% vs 8.6%
Local catheter-site infection
primary endpoint missed (P=0.082)
26.3% vs 16.9%
Two-grade improvement, rosacea
phase 3, 463 patients (P=0.019)
24.6% vs 25.6%
Same endpoint, second rosacea trial
phase 3, 263 patients, no difference
Science

Mechanism of Action

Omiganan's first job is to break microbial membranes. Later work found a second, immune effect that its dermatology trials set out to use.

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Membrane binding and disruption

Positively charged and rich in tryptophan, omiganan partitions into negatively charged, bacteria-like membranes roughly an order of magnitude more readily than into neutral, mammalian-like ones. At low lipid-to-peptide ratios the membranes saturated, a behaviour its investigators linked to the minimum inhibitory concentration.

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Broad bactericidal and fungicidal activity

Its bactericidal and fungicidal concentrations were equal to, or two to four times, its inhibitory ones, and kill curves were clearly bactericidal. Methicillin or vancomycin resistance in staphylococci, vancomycin resistance in enterococci, and azole or echinocandin resistance in fungi hardly changed its activity.

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Amplifying interferon signals

In human blood cells omiganan increased interferon-alpha release in response to ligands of toll-like receptors 3, 7, 8 and 9, as the human cathelicidin LL-37 does, and on volunteers' skin it enhanced the inflammatory response to imiquimod, a TLR7 agonist.

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Shifting the skin microbiome

In atopic dermatitis it reduced Staphylococcus abundance and increased microbial diversity, but in facial seborrhoeic dermatitis it changed neither Staphylococcus nor Malassezia against placebo. One group has proposed that skin proteases break the peptide down, which would blunt any topical antimicrobial effect.

Evidence

Published Research

These are the omiganan studies in PubMed, read from their abstracts: the phase 2 trials in atopic dermatitis, seborrhoeic dermatitis and HPV lesions, laboratory work on its spectrum and mechanism, and animal models. The catheter and rosacea phase 3 results have not appeared as papers in PubMed; they are summarised above from the trial registrations and the sponsors' disclosures.

Human2022

Atopic dermatitis phase 2: all lesions, twice daily

Eighty patients with mild to moderate atopic dermatitis applied omiganan 1%, 1.75% or 2.5% or vehicle twice daily to all lesions for 28 days. Every omiganan group reduced Staphylococcus abundance and increased microbial diversity, and cultured S. aureus fell 93.5% on 2.5% against vehicle (95% CI -99.2 to -28.5%), but there was no significant clinical improvement; the authors concluded that targeting the microbiome alone does not work in mild to moderate disease.

PMID: 33010325
Human2020

Atopic dermatitis phase 2: one lesion, once daily

Thirty-six patients applied omiganan 1%, 2.5% or vehicle gel to one target lesion once daily for 28 days. The 2.5% gel gave small but significant improvements over vehicle in local SCORAD (-18.5%; 95% CI -32.9 to -1.0) and morning itch, and both strengths shifted the lesion's bacteria towards those of non-lesional skin.

PMID: 32315497
Human2023

Facial seborrhoeic dermatitis, against ketoconazole

In a patient- and evaluator-blinded trial, omiganan 1.75% twice daily for four weeks was safe and well tolerated but did not improve facial seborrhoeic dermatitis or its biomarkers against placebo. Ketoconazole 2% did, lowering Malassezia abundance and restoring barrier function; omiganan's antimicrobial and antifungal properties could not be demonstrated on the skin.

PMID: 37762625
Human2020

Genital warts and vulvar HSIL, phase 2

In two randomised trials, 24 patients with external anogenital warts and 12 with vulvar high-grade squamous intraepithelial lesions applied omiganan 2.5% or placebo gel once daily for 12 weeks. Lesion count and size, pain, itch and quality of life did not differ; all 27 adverse events were mild and self-limiting, and human papillomavirus load fell 96.6% against placebo in the wart patients only.

PMID: 31755993
Human2020

With imiquimod on healthy volunteers' skin

Sixteen healthy volunteers received topical imiquimod, omiganan or both for up to 4 days on tape-stripped skin. Omiganan enhanced imiquimod's inflammatory response, raising perfusion by 17.1% (95% CI 5.6% to 30%) and erythema, increasing IL-6, IL-10, MxA and interferon-gamma, and drawing in more CD4, CD8 and CD14 cells.

PMID: 32043302
In Vitro2020

Interferon responses in human blood cells

In human peripheral blood mononuclear cells, omiganan enhanced interferon-alpha release in response to ligands of the endosomal toll-like receptors 3, 7, 8 and 9, as LL-37 does; plasmacytoid dendritic cells were the main source with TLR9 ligands. The molecular mechanism was not identified.

PMID: 32314872
Review2003

MBI-226 at the start of phase 3

A drug profile of Micrologix and Fujisawa's gel, developed to treat and prevent infections caused by antibiotic-resistant and antibiotic-sensitive bacteria. It records that a phase 3 trial of MBI-226 for preventing catheter-related bloodstream infections began in September 2000.

PMID: 14508884
Review2006

Omiganan at the front line of antimicrobial peptides

Indolicidin, a ribosomally synthesised antimicrobial peptide, served as omiganan's template. The review describes omiganan as the most advanced antimicrobial peptide in clinical development, aimed at catheter-related bloodstream infections and with trial evidence against acne, and notes that its exact mode and site of action were unsettled beyond a fundamental role for membrane interaction.

PMID: 18221145
In Vitro2004

Spectrum against 1,651 clinical isolates

Tested against 1,437 recent clinical bacterial isolates and 214 yeast isolates, omiganan was highly active; its bactericidal or fungicidal concentrations were equal to, or two to four times, its minimum inhibitory concentrations, and kill curves showed a clear bactericidal pattern.

PMID: 15273128
In Vitro2008

Catheter pathogens, resistant strains included

All 390 gram-positive and 167 gram-negative isolates collected in 2005-06 were inhibited at or below 128 and 1,024 mg/L. Coagulase-negative staphylococci were most susceptible (MIC50/90 4 mg/L) and every Staphylococcus aureus was inhibited at 32 mg/L or less; methicillin, vancomycin and penicillin resistance did not change potency, against 10,000 mg/L in the 1% gel.

PMID: 18310135
In Vitro2008

MRSA with reduced vancomycin susceptibility

All 109 MRSA isolates, including vancomycin-tolerant, -intermediate and -resistant strains, were inhibited by 64 µg/mL or less (MIC50/90 16/32 µg/mL); MIC90 values were only two-fold higher for tolerant and intermediate strains than for wild type.

PMID: 18178361
In Vitro2008

Fungal catheter pathogens

Omiganan inhibited 106 Candida isolates at 256 µg/mL or less and moulds, including 10 Aspergillus isolates, at 1,024 µg/mL or less, including species with reduced susceptibility to azoles and echinocandins, all well below the 10,000 µg/mL of the 1% clinical gel.

PMID: 18180345
In Vitro2021

Candida from bloodstream and vaginal infections

Against Candida strains from bloodstream infections, and consistent with earlier work on vulvovaginal isolates, most combinations of omiganan with fluconazole were additive and some were synergistic, with effects at far lower concentrations than either drug needed alone.

PMID: 34439051
In Vitro2007

How it binds bacterial membranes

In vesicle models, omiganan partitioned into anionic, bacteria-like membranes with constants of 18.9 and 43.5 thousand, about an order of magnitude higher than into neutral, mammalian-like membranes (3.7 thousand). At low lipid-to-peptide ratios the membranes saturated, which the authors related to the minimum inhibitory concentration.

PMID: 17383609
In Vitro2017

Skin proteases, and an all-D version

The authors trace the end of omiganan's catheter development in 2009 to a lack of efficacy and hypothesise that proteases in human skin degraded the peptide. They tested omiganan and its all-D enantiomer in a human skin protease stability assay and against clinical mupirocin-resistant MRSA isolates, to gauge the all-D form's potential as a topical antibacterial.

PMID: 28581672
Animal2009

Skin colonisation in pig and guinea-pig models

On ex vivo pig skin, 0.1% to 2% gels killed gram-positive and gram-negative bacteria and yeasts in a dose-dependent way, maximal at 1% to 2%, with no difference between methicillin-resistant and -sensitive S. aureus; the 1% gel cut Staphylococcus epidermidis counts by 2.7 log units at 1 hour and 5.2 at 24 hours. A guinea-pig skin model confirmed the antimicrobial and antifungal activity.

PMID: 19524411
Animal2017

Rat peritonitis and colonic anastomosis

In 40 rats with sepsis from caecal ligation and puncture, omiganan was injected into the abdomen daily for 7 days after a colonic anastomosis, alone or with imipenem. Only omiganan plus imipenem restored bursting pressure to control levels with re-epithelialisation, and omiganan with or without imipenem controlled inflammatory parameters better than imipenem alone.

PMID: 28804554
Animal2022

A liposomal gel in mouse dermatitis models

Omiganan loaded into liposomes (72% encapsulation, 120 nm vesicles) and set in a gel released it in a controlled way and permeated skin better than conventional gel or lotion. In mouse models of atopic dermatitis and psoriasis it lowered pro-inflammatory cytokines and improved lesions more than the conventional formulations.

PMID: 35878872
Dosing

Dosing Data

Omiganan was never approved, so these are the formulations its trials used. All were gels applied to the skin.

Investigational only. No approved omiganan product exists, and anything sold under the name outside a trial is not the gel the trials studied.
ProtocolDoseFrequencyDurationRoute
Atopic dermatitis phase 2 (2022) Human studyPMID 330103251%, 1.75% or 2.5% gelTwice daily28 daysTopical, all lesions
Genital warts and vulvar HSIL (2020) Human studyPMID 317559932.5% gelOnce daily12 weeksTopical

Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.

A gel, not a vial
Omiganan was only ever studied as a ready-made topical gel, so there is nothing to reconstitute or measure by syringe.
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Safety

Side Effects & Contraindications

Reported Side Effects

From the trials above and the rosacea trial registrations.

● Mild, local and self-limiting — all 27 adverse events in the genital wart and vulvar HSIL trials
● Treatment-related adverse events in 48 of 307 patients over up to 12 months in the rosacea open-label extension
● Serious adverse events matched vehicle in the 463-patient rosacea phase 3 (4 of 235 against 4 of 228)
● More skin inflammation with imiquimod — perfusion and erythema rose further in volunteers given both

Contraindications & Cautions

Omiganan has no label. These cautions come from its trials; they are not instructions.

● Products outside a trial — no approved omiganan exists, so identity, strength and sterility are unverified
● Combination with imiquimod — omiganan amplified imiquimod's skin inflammation in volunteers
● Catheter protection — both catheter phase 3 trials missed their primary endpoints
● Tested athletes — check the Sport (WADA) row in the table below
Questions

Frequently Asked Questions

?Is omiganan approved?

No. FDA's Drugs@FDA database holds no application for omiganan or Omigard, and EMA's register has no entry. Development for catheter infections ended in 2009, and its rosacea programme produced one positive and one negative phase 3 trial.

?Did omiganan prevent catheter infections?

Not on its primary endpoints. The first phase 3 trial missed its bloodstream-infection endpoint, and CLIRS, in 1,859 patients, missed local catheter-site infection (6.3% against 8.6% with povidone-iodine, P=0.082), although microbiologically confirmed site infections and catheter colonisation were significantly lower.

?Does omiganan work for rosacea?

The evidence is split. In two phase 3 trials in severe papulopustular rosacea, a once-daily gel beat vehicle on both co-primary endpoints in 463 patients but not in 263, where lesion counts and two-grade improvements matched vehicle. Neither trial has appeared as a paper in PubMed.

?How is omiganan related to LL-37?

Both are cationic antimicrobial peptides of the cathelicidin family. Omiganan is a synthetic analogue of indolicidin, a cow neutrophil peptide, not of human LL-37, but in human immune cells it enhanced interferon responses to toll-like receptor ligands in the same way LL-37 does.

?Did it help eczema?

Only slightly. In a 36-patient trial the 2.5% gel improved a treated lesion's score by 18.5% against vehicle, but in an 80-patient trial treating all lesions twice daily there was no clinical improvement, even though cultured Staphylococcus aureus fell by 93.5%.

?Does omiganan kill resistant bacteria?

In the laboratory, yes: MRSA, including strains with reduced vancomycin susceptibility, vancomycin-resistant enterococci and azole-resistant fungi were inhibited at concentrations far below the 1% gel's. That laboratory activity did not become a clear clinical benefit in its trials.

Bibliography

References

  1. [pubmed] Niemeyer-van der Kolk T, et al. "Topical antimicrobial peptide omiganan recovers cutaneous dysbiosis but does not improve clinical symptoms in patients with mild to moderate atopic dermatitis in a phase 2 randomized controlled trial." J Am Acad Dermatol, 2022;86(4):854-862. PMID: 33010325.
  2. [pubmed] Niemeyer-van der Kolk T, et al. "Pharmacodynamic Effects of Topical Omiganan in Patients With Mild to Moderate Atopic Dermatitis in a Randomized, Placebo-Controlled, Phase II Trial." Clin Transl Sci, 2020;13(5):994-1003. PMID: 32315497.
  3. [pubmed] Rousel J, et al. "Treatment with the Topical Antimicrobial Peptide Omiganan in Mild-to-Moderate Facial Seborrheic Dermatitis versus Ketoconazole and Placebo: Results of a Randomized Controlled Proof-of-Concept Trial." Int J Mol Sci, 2023;24(18). PMID: 37762625.
  4. [pubmed] Rijsbergen M, et al. "Results of phase 2 trials exploring the safety and efficacy of omiganan in patients with human papillomavirus-induced genital lesions." Br J Clin Pharmacol, 2020;86(11):2133-2143. PMID: 31755993.
  5. [pubmed] Niemeyer-van der Kolk T, et al. "Omiganan Enhances Imiquimod-Induced Inflammatory Responses in Skin of Healthy Volunteers." Clin Transl Sci, 2020;13(3):573-579. PMID: 32043302.
  6. [pubmed] Grievink HW, et al. "Antimicrobial Peptide Omiganan Enhances Interferon Responses to Endosomal Toll-Like Receptor Ligands in Human Peripheral Blood Mononuclear Cells." Clin Transl Sci, 2020;13(5):891-895. PMID: 32314872.
  7. [pubmed] Isaacson RE. "MBI-226. Micrologix/Fujisawa." Curr Opin Investig Drugs, 2003;4(8):999-1003. PMID: 14508884.
  8. [pubmed] Melo MN, et al. "Omiganan pentahydrochloride in the front line of clinical applications of antimicrobial peptides." Recent Pat Antiinfect Drug Discov, 2006;1(2):201-7. PMID: 18221145.
  9. [pubmed] Sader HS, et al. "Omiganan pentahydrochloride (MBI 226), a topical 12-amino-acid cationic peptide: spectrum of antimicrobial activity and measurements of bactericidal activity." Antimicrob Agents Chemother, 2004;48(8):3112-8. PMID: 15273128.
  10. [pubmed] Fritsche TR, et al. "Antimicrobial activity of omiganan pentahydrochloride tested against contemporary bacterial pathogens commonly responsible for catheter-associated infections." J Antimicrob Chemother, 2008;61(5):1092-8. PMID: 18310135.
  11. [pubmed] Fritsche TR, et al. "In vitro activity of omiganan pentahydrochloride tested against vancomycin-tolerant, -intermediate, and -resistant Staphylococcus aureus." Diagn Microbiol Infect Dis, 2008;60(4):399-403. PMID: 18178361.
  12. [pubmed] Fritsche TR, et al. "Antimicrobial activity of omiganan pentahydrochloride against contemporary fungal pathogens responsible for catheter-associated infections." Antimicrob Agents Chemother, 2008;52(3):1187-9. PMID: 18180345.
  13. [pubmed] Żyrek D, et al. "The Antimicrobial Activity of Omiganan Alone and In Combination against Candida Isolated from Vulvovaginal Candidiasis and Bloodstream Infections." Antibiotics (Basel), 2021;10(8). PMID: 34439051.
  14. [pubmed] Melo MN, et al. "Omiganan interaction with bacterial membranes and cell wall models. Assigning a biological role to saturation." Biochim Biophys Acta, 2007;1768(5):1277-90. PMID: 17383609.
  15. [pubmed] Ng SMS, et al. "Preliminary investigations into developing all-D Omiganan for treating Mupirocin-resistant MRSA skin infections." Chem Biol Drug Des, 2017;90(6):1155-1160. PMID: 28581672.
  16. [pubmed] Rubinchik E, et al. "Antimicrobial and antifungal activities of a novel cationic antimicrobial peptide, omiganan, in experimental skin colonisation models." Int J Antimicrob Agents, 2009;34(5):457-61. PMID: 19524411.
  17. [pubmed] Lorenzi T, et al. "Effect of omiganan on colonic anastomosis healing in a rat model of peritonitis." Am J Transl Res, 2017;9(7):3374-3386. PMID: 28804554.
  18. [pubmed] Javia A, et al. "Liposomes encapsulating novel antimicrobial peptide Omiganan: Characterization and its pharmacodynamic evaluation in atopic dermatitis and psoriasis mice model." Int J Pharm, 2022;624:122045. PMID: 35878872.
  19. [clinical-trial] Cadence Pharmaceuticals. "A Phase 3, Multicenter, Randomized, Evaluation Committee-Blinded Study to Assess the Efficacy of Topical Omiganan 1% Gel in Preventing Local Catheter Site Infections/Colonization in Patients Undergoing Central Venous Catheterization" (CLIRS). ClinicalTrials.gov NCT00231153; completed July 2008; results read September 30, 2026.
  20. [clinical-trial] Maruho Co., Ltd. (Cutanea Life Sciences). Phase 3 trial of once-daily CLS001 (omiganan) gel versus vehicle for 12 weeks in papulopustular rosacea, with an open-label safety extension. ClinicalTrials.gov NCT02547441; primary completion July 5, 2017; results read September 30, 2026.
  21. [clinical-trial] Maruho Co., Ltd. (Cutanea Life Sciences). Phase 3 trial of once-daily CLS001 (omiganan) gel versus vehicle for 12 weeks in papulopustular rosacea. ClinicalTrials.gov NCT02576860; primary completion February 27, 2017; results read September 30, 2026.
  22. [clinical-trial] Maruho Co., Ltd. (Cutanea Life Sciences). Phase 3 open-label extension of omiganan topical gel in rosacea (long-term safety). ClinicalTrials.gov NCT02576847; primary completion July 14, 2017; results read September 30, 2026.
  23. [news-release] Cadence Pharmaceuticals. "Cadence Pharmaceuticals, Inc. Announces Plan to Increase Number of Patients to Be Enrolled in Its Phase III Clinical Trial of Omigard." Press release, April 30, 2007 (describes the first phase 3 trial: 1,407 patients, 27 US centres, completed February 2003). Read September 30, 2026.
  24. [fda] FDA. Drugs@FDA (openFDA): no application for omiganan or Omigard. Read September 30, 2026.
  25. [other] European Medicines Agency. Medicines register (centrally authorised human medicines): no entry for omiganan. Read September 30, 2026.

Sources & Citations

Every study on this page was read from its PubMed record. The catheter and rosacea phase 3 results come from their ClinicalTrials.gov records and the sponsors' disclosures, and approval status from FDA's Drugs@FDA database and EMA's register, read September 30, 2026. Grey Peptides sells nothing and links to no vendor.

Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.

Last reviewed: 2026-09-30