No generic versions of Silenor (doxepin tablets) are available at this time. Although it's unclear why no generic versions have been introduced, it's likely that the drug is still protected by another patent that has not yet expired. It's important to note that doxepin is the active ingredient in this product, but it is not the same thing as a "generic version."
Silenor® (doxepin tablets) is a prescription medication approved for the treatment of insomnia. Specifically, it is approved for treating insomnia that is characterized by difficulty staying asleep (instead of difficulty falling asleep). Silenor contains a very low dose of doxepin, a medication that has long been used for treating depression and anxiety.
Silenor is made by Somaxon Pharmaceuticals, Inc. The medication is protected by patents that prevent any generic versions from being sold in the United States.
The first patent for Silenor expired in March 2013. Yet, no generic versions are available. This suggests that other, later-expiring patents may still be protecting the drug from generic competition. The next patent for Silenor is set to expire in January 2015. This is the earliest predictable date that a generic version of the drug could become available.
However, this could change, depending on many factors, such as lawsuits or additional patents. Once Silenor goes off-patent, there may be several companies that will manufacture a generic Silenor drug.
There are several patents, some of which do not expire for several years. In July 2012, the manufacturer of Silenor settled a lawsuit with Mylan (a generic manufacturer), allowing Mylan to sell a generic version "early" in January 2020. This suggests that the drug will probably be protected by generic competition until then.