Zudena 100 mg is legally authorized for sale in India from the current CDSCO database. CDSCO is India's central authority responsible for regulating the approval, import, manufacture, distribution, and sale of medicines. Zudena 100 mg is marketed as udenafil 100 mg, an erectile-dysfunction medicine. The legality of the active ingredient is different from whether a particular brand/manufacturer and formulation is approved and licensed for sale in India. So, if you're considering buying it, I would not assume that an online listing means the product is legally approved or genuine. Check the package for the manufacturer, manufacturing licence details, batch number and regulator information, and preferably obtain it through a licensed pharmacy. If you tell me where you are buying Zudena 100 mg (India or another country), I can check the relevant regulator specifically.