Abstract: Hemoglobin molecules are coupled so as to increase their intravascular residence times without significantly diminishing their oxygen transport ability. This is achieved by coupling hemoglobin molecules to one another and/or to serum proteins and gelatin derivatives using dialdehydes such as aliphatic dialdehydes of 3 to 8 carbon atoms, optionally followed by addition of pyridoxal phosphate. The desired material isolated by ammonium sulfate precipitation, the sulfate being added before, simultaneously with, or after the dialdehyde. Solution of the precipitate followed by dialysis and/or ion exchange can also be undertaken.

Abstract: Hemoglobin preparation suited for intravenous injection with increased oxygen release in relation to erythrocytes or hemoglobin solution, comprising a substantially pyrogen-free condensation product of hemoglobin and pyridoxal phosphate having a retention time in the blood vessel from about 2 to 9 hours. It is produced by washing human erythrocytes at least four times with a weakly alkaline solution, then hemolyzing and treating the material with a cation exchange resin in the H+ form until the pH value has dropped to about 5 to 5.5, separating the material from resin and any precipitated stroma, diluting the material to a hemoglobin concentration of about 5 to 9%, adjusting the pH to about 7 to 9, displacing any oxygen therein, and adding about 0.25 to 1.25 g of pyridoxal-5-phosphate per liter of hemoglobin solution of 5 to 9% concentration.