HEMOGLOBIN MULTIPLE EMULSION AS AN OXYGEN DELIVERY SYSTEM

Multiple emulsion technology provides a mechanism for the encapsulatio n and in vivo delivery of drugs, proteins, and other materials which w ould otherwise be degraded, cleared rapidly, or toxic to the host. The se feasibility studies were performed to evaluate a prototype Hb multi ple emulsion as a stable oxygen delivery system. A concentrated soluti on of hemoglobin (Hb) was encapsulated in the form of a Hb-in-oil-in-w ater (Hb/O/W) multiple emulsion. Studies using mineral oil demonstrate d that Hb multiple emulsions have several important characteristics th at are compatible with utility as a blood substitute, These include: s atisfactory rheological properties and good hydrodynamic stability com pared to whole blood, high encapsulation concentration of Hb and high encapsulation efficiency with little met-hemoglobin generation, and sa tisfactory oxygen affinity and cooperativity compared to whole blood. Isovolemic exchange transfusions of Hb/O/W multiple emulsion can suppo rt life in rats whose hematocrit has been reduced to levels (5% or low er) that are incompatible with survival, and induces no acute toxicity . These results are consistent with the utility of Hb/O/W as an oxygen -carrying red blood cell substitute or organ perfusion media.