Xanthine oxidase inhibitors for gout: Applications and novel drug development

Hyperuricemia is a well-established direct trigger of gouty arthritis. Xanthine oxidase (XO), the rate-limiting enzyme in uric acid production, represents a core therapeutic target for gout. Although XO inhibitors like allopurinol and febuxostat are widely-used clinically, their limitations, including severe hypersensitivity and cardiovascular risks, necessitate the continuous pursuit of safer and more efficient agents. This review provides a systematic and critical assessment of recent advances in XO inhibitor research, proposing for the first time a unified classification framework based on the evolution of drug design strategies. We comprehensively cover diverse chemical entities, from structure-based, rationally designed compounds to natural products and their corresponding analogs, with a particular emphasis on cutting-edge strategies designed to overcome existing drawbacks. These include dual-target inhibitors (e.g., targeting XO/URAT1 or XO/NLRP3) and drug repurposing. By delving into the structure-activity relationships within each inhibitor class, we identify crucial pharmacophores and optimization principles. Finally, the review offers a forward-looking perspective, critically discussing current research challenges and outlining future directions, such as leveraging artificial intelligence and advanced computational simulations for lead optimization. This work is intended to serve as a clear theoretical blueprint and a practical source of inspiration for medicinal chemists designing the next generation of highly effective and low-toxicity anti-gout therapeutics.