Provided is a lipid-based dispersion comprising, a) phosphatidyl choline b) an anionic phospholipid c) up to 1% cholesterol by weight of total lipids and d) propofol wherein the lipid-based dispersion comprises liposomes and the liposomes have a particle size measured by dynamic light scattering of less than 100 nm. The composition is useful in producing a sedative or anesthetic for an animal.