Stendra avanafil : This is an as-needed medication taken 30 minutes before sex and can last up to six hours. All PDE5 inhibitors, including Viagra and Cialis, require a valid prescription regardless of the pharmacy or provider. Contact your medical provider if you experience any side effects during treatment. That’s not to say there aren’t just as many illegitimate sites. It’s best to check your chosen provider’s site for more information.Generic name: tadalafil [ ta-DAL-a-fil ] Brand names: Adcirca, Cialis Drug class: Impotence agents Medically reviewed by Sanjai Sinha, MD. Last updated on Uses Warnings Before taking Dosage Side effects Interactions FAQ What is Cialis? Tadalafil is in a class of drugs called phosphodiesterase-5 (PDE5) inhibitors and is available in a generic form often called generic Cialis. Tadalafil has been on the market since and. We have good news for you: generic Cialis, used to treat erectile dysfunction (ED) and enlarged prostates, just hit pharmacies. Prices for the generic, known as tadalafil, are more than 50% less than those of brand-name Cialis. As more men are able to afford tadalafil and treat their ED, it’s likely that many will have questions.