Pexiganan_Dosage, benefits & legal status
Also known as MSI-78, Locilex, Cytolex, pexiganan acetate
A magainin-based antimicrobial cream, tested twice for diabetic foot infections and never approved.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Pexiganan?
Plain language first. The technical label stays, but it never stands alone.Overview
It kills bacteria in a lab dish, including drug-resistant strains, but it has not been shown to clear infections better than standard wound care. It was never approved, and no developer has reported work on it since 2019.
Pexiganan is a 22-residue synthetic analogue of magainin, an antimicrobial peptide from frog skin. It kills bacteria by disrupting their membranes. Magainin Pharmaceuticals developed it as a cream (Locilex) for infected diabetic foot ulcers; the FDA declined it in 1999, and Dipexium's two placebo-controlled phase 3 trials failed in 2016.
What it's used for
A never-approved antimicrobial cream for infected diabetic foot ulcers. Two 2016 phase 3 trials found it no better than an inactive cream.
How does Pexiganan work?
What it does in the body, and where.Pexiganan is a positively charged, 22-residue copy of magainin 2 with an amidated end.
- 01Membrane attackIt binds the negatively charged membranes of bacteria and disrupts them. Biophysics work describes it forcing lipid bilayers into curved, unstable shapes; Dipexium describes pore formation.
- 02Broad spectrumAgainst 3,109 clinical isolates, it inhibited most genera at 32 mcg/mL or less, and antibiotic-resistant strains were as sensitive as others. It killed a million Pseudomonas per mL within 20 minutes at 16 mcg/mL.
- 03ResistanceShort laboratory tests found none. Long selection experiments over 600 to 700 generations produced resistant E. coli and Pseudomonas, and resistant S. aureus that was also less sensitive to a human defensin.
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.
Against oral antibiotics, 1990s
tested-and-failed- Human trialTwo double-blind trials, 835 people randomised to pexiganan cream or oral ofloxacin: 85 to 90% improved in both arms. One trial failed to show equivalence; the other and the pooled data passed.
- RegulatoryAn FDA advisory committee reportedly voted 7 to 4 against approval in 1999, finding no safety problems but efficacy short of equivalence. This comes from trade press; the FDA minutes were not found.
Against placebo cream, 2016
tested-and-failed- Human trial389 people with infected diabetic foot ulcers, 14 days of treatment: infection resolved in 54.4% on pexiganan against 56.5% on placebo cream, pooled across both trials. Bacterial eradication was also no better.
- Human trialSerious adverse events, pooled: 9.3% on pexiganan against 2.4% on placebo, mostly bone and skin infections.
Lab work
Early research- Lab studyBactericidal against most of 3,109 clinical isolates at 32 mcg/mL or less, with no loss of activity against antibiotic-resistant strains.
- Lab studyLong laboratory selection produced resistant E. coli, Pseudomonas and S. aureus, some with cross-resistance to a human defensin.
It is not an approved antimicrobial peptide anywhere. It did not beat oral antibiotics: the 1990s trials tested equivalence, and one of the two did not show even that. The 1999 rejection is sometimes blamed only on manufacturing; the not-approvable letter cited manufacturing issues, but the advisory committee had not endorsed its efficacy. The 2016 placebo-controlled trials failed, and in OneStep-1 the response rate was lower on pexiganan. Resistance can develop: long laboratory selection produced it. The 835 figure is everyone randomised in the 1990s trials, both arms. 'Not absorbed into the body' is a company claim without published blood-level data.
The published record
Papers and trials about Pexiganan
60 papers tagged human · 42 not reviews or lab · 1 clinical trial publications
4 registered trials · 2 with posted results
Furthest stage reached: Phase 3, results posted
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 Pexiganan
Evidence
Investigational
Category
Immune support
Common vial
Varies
Half-life
Nothing published
How much, and do you cycle it?
The range, and whether you take breaks.0.8% cream twice daily (last trials), twice daily for 14 days (trials). A 14-day course in the trials Discontinued
Applied twice daily for 14 days (up to 28 in the 1990s trials), like any topical antibiotic course. No product exists.
Nothing publishedNo figure
Applied to the skin. Dipexium said it had not been systemically absorbed, but no blood-level or half-life data were found in its filings, the trial records or the published papers.
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.Pexiganan is not injected
It is taken on the skin (topical cream). The 2016 trials used 0.8% cream twice daily for 14 days alongside standard wound care. The 1990s trials used 1% or 2% cream twice daily for 14 to 28 days, and the NDA covered the 1% cream. Dipexium's 2014 prospectus describes Locilex as 1% pexiganan acetate cream and its later filings as 0.8% pexiganan cream, with no reason given. No product exists.
How do you store it?
Before mixing, and after.Room temperature, out of light. Cap it tight after each use.
Pexiganan ships as a cream, gel, or serum. Keep it at room temperature away from sun and heat unless the label says otherwise. Refrigerating an emulsion can split the texture. Watch for color, smell, or separation changes and stop using it if any appear.
What are the side effects and cautions?
Known cautions and warnings for this compound.Solubility, computed: 50% charged residues, 45% 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
- Any use as a treatment: no product exists, and the last trials showed no benefit over placebo cream
- An infected diabetic foot ulcer treated without medical care: a lab-grade cream is not a substitute for antibiotics and wound care
Stop and get help
- Spreading redness, warmth or swelling around a wound
- Fever, chills, a foul smell or blackened tissue at the wound
- New pain deep under an ulcer, a possible sign of bone infection
Common effects
- In the 2016 trials, side effects overall were about as common as on placebo: 26 of 85 against 25 of 104, and 25 of 97 against 21 of 103
- Serious side effects were more common: 17 of 182 (9.3%) against 5 of 207 (2.4%) pooled, mostly osteomyelitis and cellulitis
- No deaths in either trial
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Pexiganan approved?
And where the numbers on this page come from.No. Pexiganan is not approved anywhere and is currently in company-run clinical trials. There is no legal route to obtain it outside a trial.
- Approval statusInvestigational
- RouteOn the skin (topical cream)
- Checked11 October 2026
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesFDA GSRS substance record, pexiganan (UNII TVF29Q70Q1)ClinicalTrials.gov, OneStep-1 posted results (NCT01590758)ClinicalTrials.gov, OneStep-2 posted results (NCT01594762)Dipexium, OneStep topline results (8-K exhibit, Oct 2016)Lipsky BA et al., Clinical Infectious Diseases 2008;47:1537-45Federal Register, Anti-Infective Drugs Advisory Committee notice (9 Feb 1999)Dipexium, Form 10-K for 2014Ge Y et al., Antimicrobial Agents and Chemotherapy 1999Perron GG et al., Proceedings of the Royal Society B 2006
What has happened recently
Never approved anywhere. An FDA advisory committee reviewed NDA 20-930 for the 1% cream on 4 March 1999 and was reported to vote 7 to 4 against; a not-approvable letter followed in July 1999. Dipexium bought the rights in 2010 and ran two placebo-controlled phase 3 trials under a Special Protocol Assessment; both failed in October 2016. Dipexium merged into PLx Pharma in 2017, and PLx wrote off the Locilex assets that year. PLx sold its assets through bankruptcy in 2023, and the current owner of the pexiganan rights is unknown.
You can compare this against the whole library, or read how to check a seller.
What else is like Pexiganan?
Others in Immune support, side by side.If you're weighing Pexiganan, it's worth reading Splenopentin, Thymopentin (TP-5), and Tuftsin in the same class.
A magainin-based antimicrobial cream, tested twice for diabetic foot infections and never approved.
- Dose
- 0.8% cream twice daily (last trials)
- How often
- Twice daily for 14 days (trials)
A five-amino-acid spleen peptide, sold on an evidence base almost nobody has read.
- Dose
- Research only
- How often
- Not established
Five amino acids that carry the whole activity of a thymus hormone.
- Dose
- 50 mg per dose
- How often
- 3x per week
A four-amino-acid immune peptide from the 1970s, and the parent of Selank.
- Dose
- Research only
- How often
- Not established
Guides for this compound
- 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.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
- How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.
Sources
- FDA GSRS substance record, pexiganan (UNII TVF29Q70Q1)(2026)22-residue sequence with a C-terminal lysinamide. Formula C122H210N32O22, MW 2477.18. INN pexiganan, CAS 147664-63-9.
- ClinicalTrials.gov, OneStep-1 posted results (NCT01590758)(2017)Clinical response at day 28: 43 of 85 (50.6%) on pexiganan against 63 of 104 (60.6%) on placebo cream. Serious adverse events 9 of 85 against 3 of 104.
- ClinicalTrials.gov, OneStep-2 posted results (NCT01594762)(2017)Clinical response at day 28: 56 of 97 (57.7%) against 54 of 103 (52.4%). Serious adverse events 8 of 97 against 2 of 103.
- Dipexium, OneStep topline results (8-K exhibit, Oct 2016)(2016)389 patients at 59 US centres. Neither trial met its primary endpoint of superiority over vehicle cream; higher than expected osteomyelitis and cellulitis.
- Lipsky BA et al., Clinical Infectious Diseases 2008;47:1537-45(2008)Two 1990s trials, 835 randomised to pexiganan cream or oral ofloxacin: clinical improvement 85 to 90% in both arms. Study 303 did not show equivalence; Study 304 and the pooled data did.
- Federal Register, Anti-Infective Drugs Advisory Committee notice (9 Feb 1999)(1999)Meeting on 4 March 1999 to discuss NDA 20-930, pexiganan acetate 1% cream, for infections in diabetic foot ulcers.
- Dipexium, Form 10-K for 2014(2015)Development history from Magainin to Dipexium; July 1999 not-approvable letter attributed to manufacturing issues. Composition patent expired June 2016.
- Ge Y et al., Antimicrobial Agents and Chemotherapy 1999(1999)Tested against 3,109 clinical isolates; bactericidal; resistant strains as susceptible as others; no resistance after 7 passages.
- Perron GG et al., Proceedings of the Royal Society B 2006(2006)22 of 24 E. coli and Pseudomonas lineages evolved heritable pexiganan resistance over 600 to 700 generations of selection.
Beyond these, 172 records are indexed. Browse the records