A pharmacological framework for integrating treating the host, drug repurposing and the damage response framework in COVID-19.

With any new disease a framework for the development of preventative or treatment therapeutics is key; the absence of such in COVID-19 has enabled ineffective and potentially unsafe treatments to be taken up by governments and clinicians desperate to have options for patients. As we still have few therapies and nil vaccines yet available, the void of a clear framework for research and practice is increasingly clear. We describe a framework that has been used to prioritise therapeutic research in previous pandemics which could be used to progress clinical pharmacology and therapeutics research in COVID-19. This is particularly relevant as discussion has already moved on from antiviral therapeutics to delineating the treatment of the host from treatment and elimination of the infective agent. Focussing on the host brings together three concepts: host treatment, the damage response framework and therapeutic repurposing. The integration of these three areas plays to the traditional strength of pharmaceuticals in providing a period of stabilization to permit time for the development of novel antiviral drugs and vaccines. In integrating approaches to repurposing, host treatment and damage response we identified three key properties that a potentially effective repurposed drug must possess by way of a framework. There must be homology, i.e., the same or similar relation with the pathogenesis of the disease, ideally targeted to the conserved pathophysiological outcomes of the viral attack; there must be a defined locus within the spectrum to prevention to severe disease and the framework must draw upon the historical dose and safety experience of the repurposed drug. To illustrate, we have mapped therapeutics that impact upon a key dysregulated pathway in COVID-19 - the renin angiotensin system - using this approach. Collectively this type of analysis reveals the importance of existing data (repurposed information and administrative observational data) and the importance of the details of the known pathophysiological response to viruses in approaches to treating the host.