Solnatide

Summary

Solnatide (also known as AP301 or TIP peptide) is an investigational synthetic 17‑amino‑acid peptide that mimics the lectin‑like domain of tumor necrosis factor. It is being studied for inhaled use in patients with moderate‑to‑severe acute respiratory distress syndrome (ARDS) to accelerate clearance of pulmonary permeability edema.

Mechanism of Action

Solnatide reproduces the lectin‑like domain of TNF and binds to the C‑terminal domain of the α‑subunit of the amiloride‑sensitive epithelial sodium channel (ENaC). This interaction activates ENaC, enhancing sodium uptake and driving alveolar fluid reabsorption, thereby reducing pulmonary edema. The peptide also engages specific oligosaccharides, contributing to anti‑inflammatory effects observed in pre‑clinical models.

What the Research Shows

Pre‑clinical studies demonstrated that solnatide reduces lung edema in animal models of ARDS and shows anti‑inflammatory activity in murine arthritis. A Phase I trial in healthy volunteers reported safety after inhalation. A Phase IIb trial protocol (2021) described sequential ascending doses in ventilated ARDS patients, with interim analysis of 16 participants (2022) showing no safety concerns and no clear efficacy differences between COVID‑19 and non‑COVID ARDS subgroups. A randomized pilot trial in COVID‑19 ARDS (2025) enrolled 30 patients; ventilator‑free days and survival were similar between solnatide (100 mg inhaled twice daily for 7 days) and placebo, and adverse events were not attributed to the drug. Overall, human data are limited to early‑phase safety and feasibility assessments, with efficacy remaining unproven.

Reported Benefits

Evidence from animal models suggests solnatide can accelerate alveolar fluid clearance by activating ENaC, potentially reducing pulmonary permeability edema. Early human trials indicate the inhaled peptide is well tolerated, with no treatment‑related serious adverse events reported. The peptide’s anti‑inflammatory properties have also been observed in pre‑clinical arthritis models, hinting at broader immunomodulatory potential.

Limitations of the Evidence

Human efficacy data are sparse and derived from small, early‑phase studies. The 2025 COVID‑19 ARDS pilot trial was stopped early and showed no difference in ventilator‑free days or mortality. Sample sizes (e.g., 30 patients) limit statistical power, and the studies focus on safety and feasibility rather than definitive clinical benefit. Consequently, the therapeutic value of solnatide in ARDS remains uncertain pending larger trials.

Safety Considerations

Across the Phase I healthy‑volunteer study and the ARDS trials, solnatide was administered by inhalation without any adverse events deemed related to the drug. Reported adverse events and serious adverse events occurred at similar frequencies in solnatide and placebo groups. While no specific safety signals have emerged, the safety profile is based on limited patient numbers, and ongoing monitoring in larger trials is warranted.

How It Is Administered

Solnatide is formulated for inhalation, typically delivered via nebulisation. In the reported pilot trial, a dose of 100 mg was administered twice daily for seven consecutive days to mechanically ventilated patients. The regimen is investigational and used only within clinical study protocols.

Routes of Administration

Goals & Uses

• Anti-inflammatory effects in lungImmunomodulationLow
• Pulmonary EdemaCardiopulmonaryModerate
• Alveolar fluid clearance in ARDSPulmonary/critical CareModerate
• Acute Lung InjuryRespiratoryModerate
• Acute respiratory distress syndromePulmonaryModerate
• Treatment of pulmonary edemaPulmonary/critical CareModerate
• Reduction of ventilator-associated conditionsPulmonary/critical CareLow

Contraindications

• Severe chronic obstructive pulmonary disease with active bronchospasmRespiratoryModerate
• Known hypersensitivity to Solnatide or any excipientsAllergyHigh
• Hypersensitivity to solnatide or excipientsAllergy/hypersensitivityHigh
• Severe airway obstruction incompatible with inhalationPulmonaryModerate

Adverse Effects

• Hypersensitivity reactionsImmunologicRare
• Local airway irritationRespiratoryCommon
• CoughRespiratoryCommonPersistent or episodic cough
• BronchospasmRespiratoryUncommon
• Throat irritationLocal / RespiratoryCommon

Drug Interactions

• DiureticsLowMay worsen dehydration or electrolyte imbalance
• Bronchodilators (e.g., albuterol)Low
• Inhaled corticosteroidsLow

Population Constraints

• Pediatric patientsAgeRelative
• Pediatric patients (<12 y)AgeRelative
• Severely immunocompromised patientsImmunologicalRelative
• Pregnant womenReproductiveRelative

Regulatory Status

• European UnionInvestigationalClinical trials under EMA oversight
• United StatesInvestigationalIND holder; Phase II trial ongoing
• United KingdomInvestigationalTrial sponsor holds Clinical Trial Authorisation

Completed Phase I trials; Phase II trials ongoing in the EU and US for ARDS and cardiogenic pulmonary edema. Not approved for any indication.

Evidence & Sources

• Safety and preliminary efficacy of sequential multiple ascending doses of solnatide to treat pulmonary permeability edema in patients with moderate-to-severe ARDS-a randomized, placebo-controlled, double-blind trial
  Journal ArticleModerateSchmid B, et al.2021-01-01T00:00:00.000000Z
• Efficacy of solnatide to treat pulmonary permeability edema in SARS-CoV-2 positive patients with moderate to severe ARDS: A randomized controlled pilot-trial
  Journal ArticleModerateKrenn K, et al.2025-01-01T00:00:00.000000Z
• Safety and preliminary efficacy of sequential multiple ascending doses of solnatide to treat pulmonary permeability edema in patients with moderate to severe ARDS in a randomized, placebo-controlled, double-blind trial: preliminary evaluation of safety and feasibility in light of the COVID-19 pandemic
  Journal ArticleModerateSchmid B, et al.2022-01-01T00:00:00.000000Z
• Conformational ensemble of the TNF-derived peptide solnatide in solution
  Journal ArticleLowMartin-Malpartida P, et al.2022-01-01T00:00:00.000000Z
• Potent anti-inflammatory activity of the lectin-like domain of TNF in joints
  Journal ArticleLowPinto ACMD, et al.2022-01-01T00:00:00.000000Z
• The Epithelial Sodium Channel-An Underestimated Drug Target
  Journal ArticleModerateLemmens-Gruber R, Tzotzos S2023-01-01T00:00:00.000000Z

Frequently Asked Questions