Before answering the question, it is important to know what Sildenafil is and its relationship with Viagra and other branded drug, Revatio, both of which are owned by the same pharmaceutical company, Pfizer Inc.
Sildenafil is a non-branded or generic name for Viagra, a medicine used for the treatment of erectile dysfunction (ED). It is also a generic name for Revatio, which is used to treat high blood pressure that affects the arteries in the lungs and right side of the heart, medically known as pulmonary arterial hypertension (PAH).
Both Viagra and Revatio contain exactly the same active ingredient, sildenafil citrate, hence the generic name, Sildenafil. This means also that Sildenafil contains exactly the same sildenafil citrate in Viagra and Revatio.
Sildenafil citrate was first developed in 1992 by Pfizer to treat PAH, under the brand name, Revatio. During the development of the drug, clinical trials showed that sildenafil citrate was more effective at causing erections than anything else. This led to the first patent to cover the use of sildenafil citrate for the treatment of ED, its issue and approval, under the brand name, Viagra.
When a drug patent expires, other companies are allowed to make their version of exactly the same active ingredient of the branded drug, under a generic (non-branded) name of the active substance. These non-branded drugs are known as generic drugs and their manufacturers, generic companies.
The benefit of offering generic drugs is that it removes the monopoly of the patent-holding company, encouraging competition and causing drug prices to drop to a better price. This allows people who need the drug to decide for themselves which drug is best for their symptoms and budget.
In the case of Pfizer, when Revatio patent expired in late 2012, generic versions of a low-dose form of the drug have been available from a number of manufacturers under the generic name, Sildenafil since early 2013.
Viagra patent in the US will expire in April 2020, but Teva Pharmaceuticals was allowed to bring its generic Sildenafil to the US market by the end of 2017, under an agreement with Pfizer. As of March 2016, at least nine other generic companies filed applications with the US Food and Drug Administration (FDA) to manufacture Sildenafil. In December 2017, Pfizer released its own generic version of Viagra, to compete with the generic companies in the non-branded drug market, where Sildenafil is available at significantly reduced prices compared to the price of Viagra.
Sildenafil, like its branded versions (Viagra and Revatio), is not available over the counter (OTC) in the US and patients must have a prescription to obtain the generic drug at local pharmacies. However, in the UK, Sildenafil is available OTC from the local pharmacy and registered online pharmacies without a prescription under the name, Viagra Connect.
It is hoped that in answering the question, this article has helped to clarify what Sildenafil is and its relationship with Viagra and Revatio.
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