Viagra

In 1983, the understanding that blood vessels play a crucial role in erection quality emerged. Dr. Giles Brindley's demonstration of using a smooth muscle relaxant for achieving an erection paved the way for future advancements in erectile dysfunction treatment.

In 1989, British Pfizer scientists Peter Dunn and Albert Wood develop a drug known as sildenafil citrate, initially intended for treating high blood pressure and angina. The drug, later named UK-92480, is found to have significant effects on erectile dysfunction.

In 1991, Dr. Nicholas Terrett was named in the British patent for sildenafil citrate, also known as Viagra, initially developed as a heart medication. He is recognized as one of the key figures in the creation of Viagra.

In 1992, Pfizer filed a patent for sildenafil to treat cardiovascular diseases, which would later be marketed as Revatio. The patent expired in 2012.

In 1994, Pfizer filed a patent for sildenafil to treat erectile dysfunction, which would later be marketed as Viagra. The patent expired in 2019.

Sildenafil, also known as compound UK-92,480, was synthesized by a group of pharmaceutical chemists led by Simon Campbell at Pfizer's research facility in England. It was initially studied for hypertension and angina pectoris.

Viagra was approved by the FDA in the United States on March 27, 1998. It revolutionized the treatment of erectile dysfunction and became a popular medication for millions of men worldwide.

In the episode 'The Man, The Myth, The Viagra' of the popular TV show 'Sex and the City', character Samantha dates a wealthy older man who uses Viagra. This episode explores the topic of older men using Viagra for sexual enhancement.

In the year 2000, Viagra sales made up 92% of the global market for prescribed erectile dysfunction pills, showcasing its significant impact and popularity in the pharmaceutical industry.

In 2002, Egypt approved Viagra for sale but later permitted local companies to produce generic versions to make it more affordable for the poor.

On August 19, 2003, the FDA approved Bayer Corporation's vardenafil hydrochloride, known as Levitra, for the treatment of erectile dysfunction in men.

FDA required a 'black box' warning in 2005 for Viagra® to alert patients of the increased risk of blindness, vision problems, and NAION (non-arteritic ischemic optic neuropathy).

A study conducted in 2006 to evaluate the safety and effectiveness of Viagra in men with erectile dysfunction who do not self-identify.

In February 2007, Boots, a UK pharmacy chain, announced plans to offer over-the-counter sales of Viagra in stores in Manchester, England, targeting males aged 30 to 65 after a consultation with a pharmacist, marking a significant shift in accessibility to the medication.

Annual sales of Viagra peaked in 2008 at US$1.934 billion, making it a great success in the pharmaceutical market.

In 2009, Boots became the first pharmacy in the UK to offer Viagra without requiring a prescription under a patient group direction. This move made the medication more accessible to individuals seeking treatment for erectile dysfunction.

In June 2010, the Federal Court of Canada invalidated Pfizer's patent 2,324,324 for Revatio, which is sildenafil used to treat pulmonary hypertension, on an application by Ratiopharm Inc.

On 8 November 2012, the Supreme Court of Canada ruled that Pfizer's patent 2,163,446 on Viagra was invalid from the beginning due to lack of full disclosure in the application.

On 9 November 2012, Teva Canada launched Novo-Sildenafil, a generic version of Viagra, following the Supreme Court of Canada's ruling on Pfizer's patent invalidity.

On 22 April 2013, the Supreme Court of Canada invalidated Pfizer's patent on Viagra altogether.

In May 2013, Pfizer announced that they would start selling Viagra directly to consumers on their website. This move came after the expiration of Pfizer's patents on Viagra outside the US in 2012.

On 21 June 2013, Pfizer's patent on sildenafil citrate expired in several EU member countries including Austria, Denmark, France, Germany, Ireland, Italy, The Netherlands, Spain, Sweden, the United Kingdom, and Switzerland.

A study published in 2014 in JAMA Internal Medicine revealed a strong correlation between the use of Viagra® and the development of melanoma, a rare but deadly form of skin cancer. The research included over 25,000 men and considered various risk factors for melanoma.

In April 2016, numerous lawsuits were consolidated into multidistrict litigation against Pfizer regarding complications related to Viagra®. Most cases involved patients who were diagnosed with melanoma after using the drug. The consolidation aimed for more efficient pretrial processing.

On May 25, 2017, the Medicines and Healthcare products Regulatory Agency (MHRA) recommended that sildenafil 50mg (Pfizer) should be available as a pharmacy medicine. This recommendation aimed to increase accessibility to sildenafil for individuals with erectile dysfunction.

In December 2017, Mylan and Teva reached an agreement with Pfizer to introduce generic versions of Viagra in the US. This followed the settlement of litigation between Pfizer and the two companies.

By 2018, the US FDA had approved fifteen drug manufacturers to market generic sildenafil in the United States. This move, including seven companies from India, is expected to result in significant price reductions.

Accessed the full text view of a clinical trial on Viagra on ClinicalTrials.gov on February 26, 2020.

New competitor products from the same class of pharmaceutical chemicals as sildenafil have been introduced, offering similar efficacy in supporting erections. This provides consumers with more options for treating erectile dysfunction.

The market for erectile dysfunction treatment is expected to reach USD 4.7 billion by 2026, indicating the increasing demand for effective solutions. Viagra's role in revolutionizing ED treatment has contributed significantly to this growth.