The short-term stability of Revex, nalmefene hydrochloride injection, was determined in a number of diluents commonly employed for intravenous use. An HPLC method was used to follow the potency of the diluted solutions, and was fully validated for its intended concentration range prior to its use. Dilutions of Revex were prepared separately in 0.9% sodium chloride injection, 0.45% sodium chloride injection, 5% dextrose injection, 5% dextrose and 0.45% sodium chloride injection, lactated Ringer's injection, 5% dextrose and lactated Ringer's injection and 5% sodium hydrogencarbonate injection. Each admixture was stored at 4 degrees C, room temperature (21 degrees C) and 40 degrees C, with samples being tested after storage at each temperature for 0, 24, 48 and 72 h. Defining stability as the retention of at least 95% of the initial drug concentration at the end of the storage period, it was concluded that the diluted solutions of Revex were uniformly stable for up to 72 h in all of the injectable solutions maintained at either 4, 21 or 40 degrees C.