Thalidomide is a sedative that was prescribed to pregnant woment in the late 1950's to alleviate 'morning sickness'. Tragically, it caused the deaths of many babies and limb abnormalities in many other infants, and was subsequently withdrawn from market. It was marketed as a racemate, ie. 50:50 mixture of the two possible enantiomers. It is possible that only one enantiomer of the drug has the teratogenic properties, however even if administered as a single enantiomer, it rapidly racemizes in the body. In more recent years, it has returned to clinical use in the treatment of leprosy and some cancers, but only under strict guidelines to avoid use in women who are or may become pregnant.