"Promethazine is a first-generation antihistamine of the phenothiazine family. The drug has anti-motion 
sickness, antiemetic, and anticholinergic effects, as well as a strong sedative effect and in some countries is prescribed for insomnia when benzodiazepines are contraindicated. It is available over-the-counter in the United Kingdom, Australia, Switzerland, and many other countries, but by prescription in the United States (brand names Phenergan, Promethegan, Romergan, Fargan, Farganesse, Prothiazine, Avomine, Atosil, Receptozine, Lergigan, and Sominex in the UK)."
"Chemically, promethazine hydrochloride appears as a white to faint yellow crystalline powder that is practically odorless. Slow oxidation may occur upon prolonged exposure to air usually causing blue discoloration. Promethazine as the hydrochloride salt is freely soluble in water and somewhat soluble in alcohol. Promethazine is a chiral compound, occurring as a mixture of enantiomers."