Can I apply for a patent for expired drugs?

Yes, it depends on what you want to do now. First, if you want to have a patent certificate, then you can apply for a patent for utility model. If your method has been patented for so long, you say it is different from the original method. According to the actual situation, I think you can still apply for a patent. The method that doesn't work is a patent in itself, and it doesn't necessarily lead to different results before applying for a patent. The mobile phones used by everyone are not from the same company. Every company that produces mobile phones has its own patent. It can be said that now that you have a mobile phone, you can't apply for a mobile phone. In addition, the utility model and appearance patent department has undergone substantive examination, so if you want to have a patent certificate, you can still apply! If you want to attack others, don't say that you have achieved the result. Even if you haven't done it or copied it from others, there may not be such a method in the world. I hope it helps you! A patent search can be conducted to see if a patent can be registered. Why patent search? 1. Avoid repeated development and make the technologies, products and methods developed by yourself exclusive. 2. See if the scientific research projects we have prepared or will develop belong to the protection scope of others' patents. After searching, no other company has applied for the patent of the product or technology we want to develop, so we can invest in R&D normally. After R&D, we can protect it by applying for a patent or using trade secrets, so that our R&D project can be used by us. If someone else has applied for an invention patent before our research and development, and has accepted or authorized it. Then we don't need to develop the same technology. Because others have applied for patent protection, even if we develop it ourselves without referring to any data and information of others, it is of little value to us. 3. By searching related patents in the same industry at home and abroad, we can also judge the business direction, technical products and market layout of other enterprises, thus helping R&D personnel and enterprises to track the development trend of technology, plan the direction of R&D and formulate market competition strategies. By mastering and analyzing the products and technologies of other enterprises, we can better complete the update and progress of various products and technologies.