How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. Some examples of nitrates are nitroglycerin Nitro-Dur, Nitrostat, others , isosorbide mononitrate Monoket and isosorbide dinitrate Bidil. Or she was alluded to. While last year, Pfizer’s patent for Viagra expired in Europe and Japan. These small differences affect the way each medication works, such as how quickly it takes effect and wears off, and the possible side effects. Oral medicines for ED usually work well and cause few side effects. The intensifying of the marketing message makes sense considering Viagra’s patent expires in 3 years, along with its monopoly.In most males,* Viagra works within 1 hour after it’s taken. It’s possible that Viagra can begin working within 30 minutes of being taken. But other times, it may take . The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called . TV Ad Attribution & Benchmarking. Marketing Stack Integrations and Multi-Touch Attribution. Real-Time Video Ad Creative Assessment. You’ve reached the age .