China
Manufacture and sale of sildenafil citrate drugs is common in China, where Pfizers patent claim is not widely enforced. Egypt
Egypt approved Viagra for sale in 2002, but soon afterwards allowed local companies to produce generic versions of the drug, citing the interests of poor people who would not be able to afford Pfizers price. European Union
Pfizers patent on sildenafil citrate expired in some member countries of the EU, Austria, Denmark, France, Germany, Ireland, Italy, The Netherlands, Spain, Sweden, the United Kingdom and Switzerland on 21 June 2013. A UK patent held by Pfizer on the use of PDE5 inhibitors (see below) as treatment of impotence was invalidated in 2000 because of obviousness; this decision was upheld on appeal in 2002. India
Manufacture and sale of sildenafil citrate drugs known as "generic Viagra" is common in India, where Pfizers patent claim does not apply. Trade names include Kamagra (Ajanta Pharma), Silagra (Cipla), Edegra (Sun Pharmaceutical), Penegra (Zydus Cadila), Manly (Cooper Pharma) and Zenegra (Alkem Laboratories). New Zealand
Sildenafil was reclassified in New Zealand in 2014 so it could be bought over the counter from a pharmacist. It is thought that this reduced sales over the Internet and was safer as men could be referred for medical advice if appropriate. South Korea
In 1999 South Korea granted two patents to Pfizer related to sildenafil. The first document guaranteed sole production and sale of the substance until 2012, while the second gave Pfizer the exclusive use to treating erectile dysfunction with sildenafil until 2014.
The liquid formulation was withdrawn because of an upward trend in spontaneous reports of adverse reactions, including syncope (fainting), which are temporally correlated with a change that was made to the formulation around April 2007 to include edetate disodium (EDTA). The upward trend in adverse reaction reporting rates had not been observed with the use of lyophilized sargramostim. The original liquid formulation without EDTA was returned to the market in the US in May 2008.In 2009, Genzyme acquired the rights to Leukine from Bayer, including the manufacturing facility in the Seattle area.In March 2018 the label was extended to use as a countermeasure for acute radiation syndrome. == References ==