Perfluorocarbon Emulsions, Platelet Counts, and Inflammation

Abstract

Perfluorocarbon emulsions (PFC) are a class of lipid-coated micelle slurries wherein the active center of the micelle is a completely halogen/fluorine-substituted hydrocarbon capable of dissolving very large quantities of nonpolar gases. Due to their unique enhanced solubility for oxygen (O2) and nitrogen (N2), PFCs have been used in research as enhanced gas transport media for situations wherein the microcirculation is dysfunctional. In the early 1990s a PFC emulsion was approved for human use during coronary artery angioplasty and one is presently in use in Russia as well as other countries. The pharmaceutical class has had reported in the past associated with variable amounts of time-limited thrombocytopenia. Anxiety about cerebral embolism surfaced after a pivotal phase III trial leading to the cessation of all human research in the United States. At that time papers both published and submitted to the FDA opined (without proof) that the platelet count decrease might be caused by platelet white cell conjugates and/or platelet aggregates, thereby signaling a general inflammatory response to PFCs and a potential thrombosis risk. Although thrombocytopenia has been reported in response to PFC emulsion formulations, it is not ubiquitous and seems to be less associated with some formulations. As well, in some recent animal studies there is no evidence of platelet white cell adverse interactions. The mechanism for the reported thrombocytopenia is as yet not fully understood, and risk-benefit profiles will have to be carefully studied as contemporary human trials move forward.