Dutasteride was patented in 1996  and was first described in the scientific literature in 1997.  It was approved by the FDA for the treatment of BPH in November 2001 and was introduced into the United States market the following year under the brand name Avodart.  Dutasteride has subsequently been introduced in many other countries, including throughout Europe and South America .  The patent protection of dutasteride expired in November 2015 and the drug has since become available in the United States in a variety of low-cost generic formulations . 
Gestodene, also known as 17α-ethynyl-18-methyl-19-nor-δ 15 -testosterone, as well as 17α-ethynyl-18-methylestra-4,15-dien-17β-ol-3-one or 13β-ethyl-18,19-dinor-17α-pregna-4,15-dien-20-yn-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone .   It is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins.  Gestodene is almost identical to levonorgestrel in terms of chemical structure , differing only in having an additional double bond between the C15 and C16 positions, and for this reason is also known as δ 15 -norgestrel or as 15-dehydronorgestrel.