Fenazox is primarily used as an intermediate in the synthesis of various pharmaceutical compounds, particularly in the development of opioid antagonists and related medications. It plays a key role in the production of drugs aimed at treating opioid dependence and overdose, such as naltrexone and naloxone derivatives. Due to its structural properties, Fenazox allows for selective modification to enhance the binding affinity and pharmacokinetics of final drug products. It is also utilized in research settings for exploring new treatments in addiction medicine and pain management. Its application is mostly confined to controlled laboratory and industrial environments due to the sensitive nature of the end-products.