Heparin has a compelling scientific and clinical rationale as a potential treatment for respiratory disease. Severe respiratory infections and COPD exacerbations involve interconnected processes including inflammation, epithelial injury, neutrophil activation, mucus obstruction, fibrin deposition and local coagulation. Heparin can act on multiple pathways involved in these processes, providing a broad mechanism of action across viral, bacterial and mixed-pathogen disease.

Targeting multiple drivers of lung injury
Heparin has demonstrated anti-inflammatory, anti-protease and anti-thrombo-inflammatory activity, while also showing potential to reduce mucus-related airway obstruction. This could complement existing treatments such as bronchodilators, corticosteroids and antimicrobials by addressing mechanisms they do not directly target.

Local delivery, designed for a favourable therapeutic window
Nebulised delivery is intended to concentrate heparin directly in the airways and alveolar surfaces where inflammation, mucus obstruction and tissue injury occur, while reducing systemic anticoagulant exposure compared with injectable administration.

Clinical evidence supports the approach
Clinical studies in COPD and acute respiratory disease provide encouraging evidence for improvements in lung function and oxygenation. Importantly, an international randomised meta-trial of nebulised unfractionated heparin in hospitalised, non-intubated COVID-19 patients demonstrated a reduction in the composite endpoint of intubation or death, as well as in-hospital mortality, with no pulmonary or systemic bleeding events reported in the nebulised heparin group.

A significant unmet need — and an opportunity for HT-231
Despite decades of clinical experience with heparin, existing injectable formulations and nebulisation approaches were not designed specifically for respiratory delivery. Challenges include viscosity, inconsistent nebuliser performance, variable delivered dose, device compatibility and uncertain lung deposition.

HT-231 is being developed to address these limitations: a purpose-designed inhaled heparin product intended to provide controlled, reproducible pulmonary delivery, supporting a differentiated therapeutic profile and a scalable path toward clinical and commercial development.

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