Pfizer Inc will bring its own generic version of its erectile dysfunction (ED) drug Viagra (sildenafil citrate) to the United States market today, seeking to preserve some sales as generic competition starts up for one of the world's most famous drugs. Teva Pharmaceutical Industries Ltd is launching its rival generic version today.

Viagra technically does not lose patent protection until 2020, but Pfizer reached a settlement with Teva in December 2013 allowing the company to launch its generic version on today's date.

New York–based Pfizer will start selling what's known as an "authorized generic," manufactured by its subsidiary Greenstone LLC, priced at $30 to $35 per pill, a company spokesman told Medscape Medical News. That's roughly half or less of the $65-a-pill cost for Viagra seen on pharmacy websites. Pfizer noted that it's difficult to determine how much of this discount will reach consumers because of markups and variations in pharmacy pricing. Israel-based Teva declined to comment to Medscape Medical News on its plans for pricing its version of generic Viagra.

Pfizer already has seen significant erosion in its sales of Viagra, an iconic blue pill that once topped $2 billion in annual revenue. With the 1998 US introduction of Viagra, Pfizer pioneered a market for erectile dysfunction drugs. Yet the drug soon faced competition from rival phosphodiesterase type 5 inhibitors, such as vardenafil (Levitra, Bayer/GlaxoSmithKline) and tadalafil (Cialis, Eli Lilly). Pfizer reported Viagra revenue of about $1.6 billion last year.

New Strategies

Pfizer already has employed two separate strategies that may help it hang onto sales in the ED market. It markets Revatio, a lower-dose version of sildenafil (the active ingredient in Viagra) intended for pulmonary arterial hypertension. And regulators in the United Kingdom last month approved a version of Viagra that can be sold without a prescription.

Pharmacy websites have for some time shown men how to save by using Revatio. GoodRx says generic and branded versions of Revatio already compete with Viagra, with "the most common version of sildenafil" costing "around $14.45, 95% off the average retail price of $291.46." In a 2013 blog post, Cooper Drug Store of August, Kansas, reported saving a customer "exactly $238.72 on just one prescription by asking his physician to prescribe generic Revatio, which was covered at a generic copay, rather than brand-name Levitra."

In the United Kingdom, regulators in November cited concerns about counterfeit versions of Viagra as a reason for allowing pharmacy sales of the drug without requiring prescriptions. In the past 5 years, the United Kingdom's Medicines and Healthcare products Regulatory Agency (MHRA) investigators seized more than £50 million of unlicensed and counterfeit erectile dysfunction medicines, the agency said.

"Making this medication more widely available will help direct men who might not otherwise seek help into the healthcare system and away from the risks that come with buying medicines from websites operating illegally," the UK regulators said in a statement.

The MHRA said that pharmacists will be able to determine whether men can get a 50-mg version of the drug, branded as Viagra Connect. The drug is not intended for patients with severe heart, liver, or kidney conditions, the UK regulators stressed.

Over-the-Counter Viagra in US Future? It's "Tricky"

For the US market, making such a switch for Viagra "would be a tricky decision, and one that's important to get right," Caleb Alexander, MD, co-director of the Center for Drug Safety and Effectiveness at the Bloomberg School of Public Health at Johns Hopkins University, Baltimore, Maryland, told Medscape Medical News. The US Food and Drug Administration in recent years has approved switches from prescription requirements to over-the-counter status for several allergy medicines.

"This would not be a slam dunk" for Viagra, Dr Alexander said of any potential bid to switch status for Viagra in the United States. "This is no Allegra. This is no Zyrtec."

Many men have ED as a result of chronic diseases, he said. For that reason, doctors need to weigh the potential risk for complications among men in poor health posed by using drugs such as Viagra.

"The same patients that have erectile dysfunction often have diabetes or heart disease or other vascular disease," said Dr Alexander, who is also a practicing primary care physician. "This is a medicine that, by virtue of the condition that it's treating, will be used [by men who] are at elevated risk for adverse events."

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