Propofol (Diprivan) is the most recent intravenous anesthetic to be introduced into clinical practice. Work in the early 1970s on substituted derivatives of phenol with hypnotic properties resulted in the development of 2,6-di-isopropofol. 325 The first clinical trial, by Kay and Rolly 326 and reported in 1977, confirmed the potential of propofol as an anesthetic induction agent. Propofol is insoluble in water and therefore was initially prepared with Cremophor EL (BASF A.G.). Because of anaphylactoid reactions associated with Cremophor EL in this early formulation of propofol, 327 the drug was reformulated in an emulsion. Propofol has been used for induction and maintenance of anesthesia as well as for sedation.