country's National Health Service. The first month's treatment of Faslodex, which starts with a loading dose, costs £1,044.82 ($1,666), and subsequent treatments cost £522.41 a month. In the 12 months ending June 2015, the UK price (excluding VAT) of a month's supply of anastrozole (Arimidex), which is off patent, cost 89 pence/day, and letrozole (Femara) cost £1.40/day. Patent extension The original patent for Faslodex expired in October 2004. Drugs subject to pre-marketing regulatory review are eligible for patent extension, and for this reason AstraZeneca got an extension of the patent to December 2011. AstraZeneca has filed later patents. A generic version of Faslodex has been approved by the FDA. However, this does not mean that the product will necessarily be commercially available - possibly because of drug patents and/or drug exclusivity. A later patent for Faslodex expires in January 2021. Atossa Genetics has a patent for the administration of fulvestrant into the breast via a microcatheter invented by Susan Love. Research Fulvestrant was studied in endometrial cancer but results were not promising and as of 2016 development for this use was abandoned. Because fulvestrant cannot be given orally, efforts have been made to develop SERD drugs that can be taken by mouth, including brilanestrant and elacestrant. The clinical success of fulvestrant also led to efforts to discover and develop a parallel drug class of selective androgen receptor degraders (SARDs). ZB716, or fulvestrant-3-boronic acid, is an oral prodrug of fulvestrant which is under development. References External links Antiestrogens AstraZeneca brands Estranes GPER agonists Hormonal antineoplastic drugs Organofluorides Peripherally selective drugs Selective estrogen receptor degraders World Anti-Doping Agency prohibited substances