Each vial of Botox Purified Neurotoxin Complex contains 100 units (U) of Clostridium botulinum toxin type A, 0.5 milligrams of albumin (human), and 0.9 milligrams of sodium chloride in a sterile, vacuum-dried form without a preservative. One unit (U) corresponds to the calculated median lethal intraperitoneal dose (LD/50) in mice of the reconstituted Botox injected.