<unk>  also called pyridoxine disulfide or pyrithioxine (European drug names Encephabol, Encefabol, Cerbon 6) is a semi-natural water soluble analog of vitamin B6 (Pyridoxine HCl). It was produced in 1961 by Merck Laboratories by bonding 2 vitamin B6 compounds (pyridoxine) together with a disulfide bridge. Since the 1970s, it has been a prescription and OTC drug in several countries for cognitive disorders and learning disorders in children. Since the early 1990s it has been sold as a nootropic dietary supplement in the United States.
It is approved for "symptomatic treatment of chronically impaired brain function in dementia syndromes" and for "supportive treatment of sequelae of craniocerebral trauma" in various European countries, including Austria, Germany, France, Italy, Portugal, and Greece.
In France it is also approved for rheumatoid arthritis as a disease modifying drug, on the basis of the results of clinical trials.
It is not licensed for use in the United Kingdom, but in many countries it is available over the counter and is widely advertised on the internet as being for "memory disturbances." From the known sales data, it is estimated that more than 100 000 individuals in European Union countries have taken<unk>  in the past five years.
One small study, with 12 subjects given<unk> , showed an improvement in performance on tests of reaction time, but not on memory tests.
Some studies have found large doses of<unk>  can help to reduce hangovers.
Common dosages are 100-1,600 mg daily, taken in 1-3 doses during the day.
Pyritinol
Gedocarnil
Tienilic acid
Prenalterol
Gitoformate
Tetrahydrozoline
Bitolterol
Diosmectite