Thiobuscaline (TB), or 4-thiobuscaline (4-TB), also known as 3,5-dimethoxy-4-butylthiophenethylamine, is a psychoactive drug of the phenethylamine and scaline families related to the psychedelic drug mescaline. It is the analogue of buscaline in which the butoxy group at the 4 position has been replaced with a butylthio group.
In his book PiHKAL (Phenethylamines I Have Known And Loved) and other publications, Alexander Shulgin lists thiobuscaline's dose range as 60 to 120mg orally and its duration as about 8hours. The effects of thiobuscaline have been reported to include a "benign and beautiful experience which never quite popped into anything psychedelic", subtle threshold effects, a vague awareness of something, being in a "wonderful place spiritually" but with "some dark edges", it being "pleasant, but certainly not psychedelic", and body discomfort. No clear hallucinogenic effects were described. Thiobuscaline is listed as being 4times more potent as a psychoactive drug than mescaline.
Thiobuscaline produced perpetual threshold psychoactive effects that did not further increase across a wide dose range of 35 to 120mg orally. Shulgin described it as "always the simple and ephemeral catalyst of euphoria without substance and without body". In addition, he said that it could not easily be classified, for instance as a psychedelic or stimulant. Instead, Shulgin likened thiobuscaline to Ariadne (4C-D), which he noted had been called an "antidepressant". He hypothesized that thiobuscaline might be beneficial for treatment of depression in certain people in the exact same way as Ariadne.
The chemical synthesis of thiobuscaline has been described. Analogues of thiobuscaline include 4-thiomescaline, 4-thioescaline, and thioproscaline (4-thioproscaline), among others.
Thiobuscaline was first described in the scientific literature by Alexander Shulgin and Peyton Jacob III in 1984. Subsequently, it was described in greater detail by Shulgin in PiHKAL in 1991.