Polymeric hemoglobin has been under active development by a number of companies for some 20 years. There are a number of well-known problems associated with blood substitutes, largely resulting from the toxic nature of the hemoglobin molecule when it is outside the normal cell environment. Several promising products have been abandoned during clinical trials due to high incidences of renal damage and failure. Products that are close to market have been shown to be relatively safe when used in small quantities for limited time periods. However, to date, the FDA has failed to approve any product for human use amid lingering safety concerns. These safety concerns include increased blood pressure, kidney failure and toxicity.
OxyVita IS Different
OxyVita is a unique ‘new generation’ blood substitute product. It is made using a novel “zero-link” technology. This technology leaves no toxic chemical residues between hemoglobin molecules and eliminates the breakdown of the tetrameric form of hemoglobin (4 molecules) into the dimeric form (2 molecules). The hemoglobin in OxyVita is polymerized into very large super-molecules that do not escape through the arterial walls into the surrounding lymphatic tissue. This eliminates the most serious side effects described above, namely increased blood pressure and kidney failure.
OxyVita technology can use any mammalian blood as the starting material for the hemoglobin source. OxyVita has many attractive chacteristics. The polymer appears as a very compact, roughly spherical material and it has increased solubility in infusion buffers. The intravascular retention time in animals has a half life 8 – 12 times longer than unmodified hemoglobin. The relative viscosity is only 1.2 times higher than that of plasma. The oncotic pressure per gram of polymer is 1/10 that of plasma thus allowing sufficient room for additives that may be necessary for preservation and lyophylization of the material.
Most importantly, experiments on animals confirm that no extravasation occurs as shown by the absence of polymers in the lymphatic circulation of tested animals. In addition, these polymers do not produce an increase in the mean arterial pressure of the infused animals. The long half life of the polymers suggests that OxyVita will catabolize through the normal protein and hemoglobin degradation processes available in liver and spleen. To date, no immunological problems have been reported.
OxyVita delivers more oxygen than regular blood. This is consistent with data from in vitro perfusion of intestinal membranes. There are clear indications that cell-free, hemoglobin-based oxygen carriers are more efficient than the red cell in keeping the perfused tissues alive. This has great importance in heart attack, stroke or organ transplant situations. For example, we believe that OxyVita can increase transplant organ viability time from four to over twenty-four hours.