Anti - nausea medication Zofran is often used for severe nausea as a result of chemotherapy, radiation, surgery, and gastroenteritis. By the final year of its patent (2006), GlaxoSmithKline's Zofran had become the 20th highest selling brand-name drug in the United States, with sales of US $1.3 billion in the first 9 months of 2006. Phenobarbital is a barbiturate, nonselective central nervous system depressant which is primarily used as a sedative hypnotic and also as an anticonvulsant. This medication is particulary helpful in managing terminal restlessness. Place a star/asterisk next to all the stereocenters in these two molecules.