Side-by-side · Research reference

LL-37vsVIP

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AHuman-MechanisticHUMAN-REVIEWED15/35 cited

BPhase 3HUMAN-REVIEWED9/42 cited

LL-37

Cathelicidin · Human AMP

Broad-spectrumAntimicrobial activity

Membrane disruptionPrimary mechanismLu 2026 He 2026

Innate immunityHost defense rolePinheiro 2026 Zhang 2026

Endogenous · Secreted at inflammation sites

VIP

Neuropeptide · VPAC1/VPAC2 Agonist · Emergency Use Authorization (COVID-19 ARDS)

IntravenousPrimary routeBrown 2023

ARDSLead indicationUdupa 2025

Phase 3Development stage

IV infusion · Inhaled (investigational)Brown 2023 Boesing 2022

01Mechanism of Action

Parameter

LL-37

VIP

Primary target

Bacterial membranes · Phosphatidylserine-exposed cellsHe 2026 Lu 2026

VPAC1 and VPAC2 G-protein-coupled receptorsUdupa 2025

Pathway

hCAP-18 precursor → Proteinase-3 cleavage → LL-37 release → Membrane insertion/disruption

VIP → VPAC1/VPAC2 activation → cAMP elevation → Pulmonary vasodilation + epithelial protection

Downstream effect

Membrane permeabilization, cytokine induction, autophagy, phagosome-lysosome fusion, chemotaxisAhmad 2026 Zhang 2026

Anti-inflammatory cytokine modulation, alveolar-capillary membrane stabilization, pulmonary smooth muscle relaxation, reduced neutrophil infiltration

Feedback intact?

—

Yes — exogenous VIP acts as physiological agonist

Origin

Endogenous human cathelicidin (37-AA fragment, residues 134–170 of hCAP-18)

Endogenous 28-amino-acid neuropeptide; synthetic analogue (aviptadil) identical to natural VIP

Antibody development

—

02Dosage Protocols

Parameter

LL-37

VIP

Endogenous expression

Constitutive in neutrophils, epithelial tissues

Upregulated during infection and inflammation.Pinheiro 2026

—

Exogenous (experimental)

Dose varies by study; antimalarial ~10–50 μM in vitro

No FDA-approved exogenous formulation.

—

Plasma levels (malaria)

Elevated in infected patients and miceHe 2026

Exogenous administration reduced parasitemia in murine models.He 2026

—

Evidence basis

In vitro, animal models, human observational

Phase 3 RCT (TESICO)Brown 2023

816-patient randomized controlled trial in COVID-19 ARDS.

Intravenous (ARDS protocol)

—

60–90 mcg/kg/day via continuous infusion

TESICO trial protocol for COVID-19 ARDS.

Infusion duration

—

12-hour continuous IV infusion dailyBrown 2023

Inhaled (investigational)

—

Variable dosing under clinical trial protocolsBoesing 2022

Delivered via nebulizer for direct pulmonary deposition.

Treatment duration

—

3–14 days (acute ARDS)

Reconstitution

—

Lyophilized powder reconstituted with sterile diluent per protocol

Half-life

—

~2 minutes (plasma)

Rapid clearance necessitates continuous infusion.

04Side Effects & Safety

Parameter

LL-37

VIP

Cytotoxicity (high dose)

Membrane disruption in host cells at supraphysiological concentrations

—

Pro-inflammatory signaling

Can exacerbate inflammation in certain contexts (context-dependent)Pinheiro 2026

—

Biofilm formation risk

LL-37-DNA complexes may stabilize dental plaque biofilmsTanabe 2026

—

Theoretical cancer risk

Immunomodulatory roles in tumor microenvironment under investigation

—

Hypotension

—

Transient vasodilation-related blood pressure drop

Tachycardia

—

Reflex tachycardia secondary to vasodilation

Infusion site reactions

—

Erythema, phlebitis (IV administration)

GI symptoms

—

Nausea, diarrhea (VIP is endogenous GI peptide)

Overall tolerability

—

Well-tolerated in Phase 3 trials; adverse event profile comparable to placebo

Absolute Contraindications

LL-37

—

VIP

·Known hypersensitivity to aviptadil or formulation components

Relative Contraindications

LL-37

·Active autoimmune disease (theoretical immune dysregulation)

VIP

·Severe hypotension or shock states (monitor blood pressure)
·Pregnancy — insufficient safety data

05Administration Protocol

Parameter

LL-37

VIP

1. Natural secretion

LL-37 is constitutively expressed in neutrophils and epithelial cells, cleaved from hCAP-18 by proteinase-3 at sites of infection or inflammation.

Reconstitute lyophilized aviptadil powder with sterile diluent per manufacturer protocol. Inspect solution for particulates — should be clear and colorless.

2. Experimental formulations

Synthetic LL-37 and derivatives (e.g., SAMP-12aa) tested in vitro and animal models. Administered via topical, intraperitoneal, or intravenous routes in research settings.

Administer as continuous 12-hour intravenous infusion via central or peripheral line. Use infusion pump for precise dosing (60–90 mcg/kg/day divided over infusion duration).

3. Stability considerations

LL-37 is resistant to pepsin degradation at gastric pH. Synthetic short peptides designed to retain this stability while reducing toxicity.Lu 2026

Monitor blood pressure, heart rate, and oxygenation continuously during first infusion. Assess for hypotension and adjust infusion rate if needed.

4. Inhaled protocol (investigational)

—

Deliver via jet or mesh nebulizer per clinical trial protocol. Patient seated upright, normal tidal breathing for 10–15 minutes.

5. Storage

—

Store lyophilized powder at 2–8 °C, light-protected. Reconstituted solution: use immediately or within 24 hours if refrigerated.