A water-soluble prodrug form, fospropofol , has recently been developed and tested with positive results. Fospropofol is rapidly broken down by the enzyme alkaline phosphatase to form propofol. Marketed as Lusedra, this new formulation may not produce the pain at injection site that often occurs with the traditional form of the drug. The US Food and Drug Administration approved the product in 2008.  However fospropofol is a Schedule IV controlled substance with the DEA ACSCN of 2138 in the United States unlike propofol.