Trends in use, spending, and prices of doxepin for insomnia

Doxepin has been prescribed since the 1960s at daily doses ranging from 25-300mg as a tricyclic antidepressant. More recently, low-dose doxepin (3-6mg/day) was found to be safe and effective for treating insomnia. In 2010, the FDA approved low-dose doxepin under a new brand name (Silenor); generic versions became available in 2020. But total use of low-dose doxepin remained lower than use of capsules. In 2023, there were 2.6 million 30-day supplies of doxepin for insomnia, which was greater than DORAs (895,000), similar to melatonin agonists (2.6 million) and less than benzodiazepine receptor agonists (29.2 million) and trazodone (70.1 million). Mean prices per 30-day supply were $526 for brand name low-dose tablets, $252 for generic low-dose tablets, $11 for 10mg capsules, and $7 for liquid. If low-dose doxepin tablets had been available at the same per-milligram price as liquid doxepin, spending would have been reduced by $73.9 million dollars (98%). Despite generic competition, low-dose doxepin tablets approved for insomnia have substantially higher prices and less use than similar doses of capsules or liquid doxepin which can be used off-label to treat insomnia. Well-intentioned repurposing of generic medications like doxepin can be hindered if the repurposing requires doses that are not interchangeable with original versions, allowing manufacturers to set high prices for the new version that can limit patient access.