Recent advances made in the synthesis of small drug molecules for clinical applications: An insight

Over decades dependency of humans on the drugs has become indispensable and irreplaceable. Thus, each year many new drugs are licensed. Nonetheless, drugs undergo rigorous testing and analysis to be available globally in economic price for the suitability of patients with different age and physiological conditions. The testing of drugs include phase I clinical trial using small group of 20–100 healthy volunteers for safety, pharmacology and efficacy; phase II clinical trial using 100–500 volunteer patients to optimize effective dose, dose interval, safety analysis and mode of delivery such as oral or intravenous; phase III clinical trial using 1000–5000 in a larger population of patients globally at different international places to collect sufficient safety and efficacy data for patenting and licencing. Moreover, thousands of drugs fail to achieve these objectives. Therefore, this mini-review intends to critically examine and assimilate the clinical applications of selected complex repurposed small drug molecules which are in different phase of trials for treating viral infection including complications due to COVID-19: (a) Remdesivir, (b) Galidesivir, (c) Favipiravir, (d) Baricitinib, and (e) Baloxavir.