Abstract: A method for making a pharmaceutical composition is described. The composition is comprised of an organic acid derivative of alpha tocopherol, and may additionally comprise other lipids. The composition may be in the form of liposomes, and as such are associated with or entrap a bioactive agent. Particularly suited for such systems are drugs stable at acidic pH, for example drugs having imidazole groups, such as pilocarpine. The composition requires a stabilizer to maintain the bilayer phase of the organic acid derivative of alpha tocopherol in a low pH environment. Such a stabilizer is for example a detergent. Upon in vivo administration of the system and concomitant increase of pH, viscosity of the preparation increases.