Omiganan
A cationic 12-mer derived from a bovine neutrophil peptide, trialled as a topical gel for catheter-site infection, rosacea, acne and HPV-related lesions without ever clearing a phase 3 endpoint.
Also known as omiganan pentahydrochloride, indolicidin analogue, CLS001, MBI-226, MX-226
Human trials — Studied in people, typically early phase or small — promising rather than proven.
Omiganan has been through a substantial clinical programme — a phase 3 catheter-site trial that reduced local colonisation but missed its primary bloodstream-infection endpoint, and phase 2 studies in rosacea, acne, atopic dermatitis and vulvar high-grade squamous intraepithelial lesions with modest or inconsistent results. It is safe and well tolerated topically. It has simply never demonstrated an effect large enough to register.
How it works
Omiganan (ILRWPWWPWRRK-NH2) is an optimised analogue of indolicidin, a peptide from the cytoplasmic granules of bovine neutrophils. Its unusually high tryptophan and proline content gives it a non-helical, wedge-shaped structure that partitions into the membrane interface rather than forming a classical amphipathic helix; it disrupts membrane integrity and also appears to interact with intracellular targets after translocation. The spectrum is broad — gram-positive and gram-negative bacteria plus Candida — which suited it to catheter-site antisepsis. In the dermatology programmes the rationale shifted toward immunomodulation: omiganan alters the skin microbiome, reduces Cutibacterium acnes and Demodex-associated inflammation, and increases local interferon signalling, which is why it was tested in rosacea, atopic dermatitis and HPV-driven vulvar lesions. The mechanism is plausible in each case; the clinical effect sizes have been small.
Targets: Microbial cytoplasmic membrane, Skin microbiome composition, Local innate immune signalling
Dosing
| Protocol | Dose | Frequency | Route |
|---|---|---|---|
| Catheter-site antisepsis trial regimenApplied to the insertion site after standard skin preparation. | — | at each dressing change | topical |
| Dermatology trial regimensApplied to affected skin. | — | once or twice daily | topical |
- · 1% omiganan gel applied to central venous catheter exit sites. The phase 3 trial reduced local catheter colonisation but missed its primary endpoint of catheter-related bloodstream infection.
- · 1% and 2.5% omiganan gel were used in phase 2 studies of rosacea, acne, atopic dermatitis and vulvar HSIL over 6-12 weeks. None led to registration.
Cycling
Trial exposures ran from a few days for catheter sites to 12 weeks for dermatological conditions. There is no marketed product and no established real-world protocol.
Pharmacology
- Half-life
- Not established — topical application with negligible systemic absorption; plasma levels in trials were generally below the limit of quantification.
- Onset
- Antimicrobial action on contact; clinical dermatology endpoints were measured over 6 to 12 weeks.
- Routes
- topical
- Molecule
- Synthetic 12-amino-acid cationic peptide, analogue of bovine indolicidin
- Sequence length
- 12 amino acids
Handling
- Diluent
- Not applicable - formulated as an aqueous gel in the clinical programme
- Lyophilised
- Freezer, -20°C, for research peptide.
- Reconstituted
- Refrigerated; use low-binding tubes because cationic peptides adsorb strongly to standard plastics.
Mixing
Research-grade omiganan pentahydrochloride is water-soluble. It has never been developed for injection and there are no human systemic safety data.
Side effects
- commonApplication-site erythema and irritation— The most consistent finding across trials.
- commonBurning or stinging on application
- uncommonPruritus
Do not use if
- Not for systemic or injected use — there are no human systemic safety data.
- Known hypersensitivity to the peptide or gel base.
- Should not be relied upon in place of established antiseptics such as chlorhexidine for catheter-site care, which have far stronger evidence.
Combining it
- redundantchlorhexidine — Both are cationic antiseptics used for skin and catheter-site preparation; chlorhexidine has substantially better outcome data.
- cautionanionic surfactants and vehicles — Anionic ingredients bind and neutralise cationic peptides, so formulation choice materially affects activity.
What to monitor
- · Local skin tolerability at each application in a dermatological setting.
- · Catheter exit site inspection for erythema, discharge and tenderness if used for that purpose.
- · No systemic laboratory monitoring is applicable.
Legal status
Not approved in any jurisdiction. Investigational and research-use only.
References
- Sader et al. 2004, omiganan pentahydrochloride spectrum of antimicrobial and bactericidal activity (preclinical)
- Phase 3 trial of topical omiganan gel for prevention of catheter-related infection (trial)
- Rijsbergen et al., phase 2 studies of omiganan gel in rosacea, atopic dermatitis and vulvar HSIL (trial)
Mechanism in depth
A synthetic cationic peptide derived from bovine indolicidin, acting by membrane permeabilisation rather than a specific enzymatic target. Developed as a topical agent to prevent catheter-related infection and later trialled in rosacea and acne.
What usually goes wrong
It is a useful case study in why antimicrobial peptides have struggled clinically: omiganan reduced catheter colonisation but failed to meet its clinical infection endpoint, and it has not been approved. Quoting the microbiological result without the clinical one overstates it considerably.
Pharmacokinetics
- Crosses blood-brain barrier
- no
Receptor targets
- Bacterial membrane — Cationic, electrostatic
Membrane permeabilisation
What to expect, and when
Topical and local.
Genuinely uncertain
- Later dermatological indications have produced mixed results and no approval.