Sulbutiamine (brand name: Arcalion) is a synthetic derivative of (vitamin B1). As a of two modified thiamine molecules, it is a lipophilic compound that crosses the more readily than thiamine and increases the levels of thiamine and thiamine phosphate esters in the brain. Sulbutiamine was discovered in Japan in an effort to develop more useful thiamine derivatives since it was hoped that increasing the of thiamine would result in better properties.
Although its clinical efficacy is uncertain, it is the only compound used to treat that is known to selectively target the areas that are involved in the condition. In addition to its use as a treatment for chronic fatigue, sulbutiamine also appears to improve and . At therapeutic dosages, it has few reported adverse effects, though it may interfere with the therapeutic outcome of . It is available for as a nutritional supplement