New Approaches and Strategies for the Repurposing of Iron Chelating/Antioxidant Drugs for Diseases of Free Radical Pathology in Medicine.

There is an urgent need for new approaches and strategies for the introduction of antioxidant drugs in medicine. Despite hundreds of clinical trials with potential antioxidants, no antioxidant drugs have so far been developed for clinical use; this is mainly as a result of commercial reasons, but also due to insufficient data for regulatory authority approval. Antioxidant activity is a physiological process essential for healthy living. However, increased production of toxic free radicals and reactive oxygen species is observed in many clinical conditions, which are associated with serious and sometimes irreversible damage. Antioxidant drug strategies may involve short- to long-term therapeutic applications for the purpose of prevention, treatment, or post-treatment effects of a disease. These strategies are different for each disease and may include the design of protocols for the inhibition of oxidative damage through iron chelation, enhancing antioxidant defences by increasing the production of endogenous antioxidants, and activating antioxidant mechanisms, as well as the administration of synthetic and natural antioxidants. Both the improvement of antioxidant biomarkers and clinical improvement or disease remission are required to suggest effective therapeutic intervention. More concerted efforts, including new academic strategies, are required for the development of antioxidant drugs in clinical practice. Such efforts should be similar to the fulfilment of orphan or emergency drug regulatory requirements, which, in most cases, involve the treatment or clinical improvement of rare or severe diseases such as neurodegenerative diseases and cancer. Promising results of antioxidant therapeutic interventions include mainly the repurposing of the iron chelating/antioxidants drugs deferiprone (L1) and deferoxamine, and also the iron-binding drug N-acetylcysteine (NAC). In some clinical trials, the lack of pharmacodynamic and ferrikinetic data, wrong posology, and insufficient monitoring have resulted in inconclusive findings. Future strategies involving appropriate protocols and drug combinations, such as L1 and NAC, appear to improve the prospect of developing antioxidant drug therapies in different diseases, including those associated with ferroptosis. New strategies may also involve the use of pro-drugs such as aspirin, which is partly biotransformed into iron chelating/antioxidant metabolites with chemopreventive properties in cancer, and also in other therapeutic interventions. A consortium of expert academics on regulatory drug affairs and clinical trials could increase the prospects for antioxidant drug development in medicine.