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Study shows Hemopure sustains tissue oxygenation and heart function during severe constriction of coronary artery.

Biopure Corporation (Cambridge, MA; 617-234-6826) announced that its investigational oxygen therapeutic, Hemopure (hemoglobin glutamer -- 250 (bovine)) has been shown to sustain myocardial tissue oxygenation and heart function during severe constriction of a coronary artery, according to results from a pharmacology study presented at the American Society of Anesthesiologists Annual Meeting this week in Dallas, Texas. The study was completed earlier this year.

"We were encouraged by previous research demonstrating Hemopure's ability to deliver oxygen to skeletal muscles in the extremities when a critical artery is almost entirely constricted," commented Thomas Standl, MD, professor of anesthesiology, University Hospital Eppendorf (Hamburg, Germany). "As a result, we initiated further studies to measure oxygen delivery during restricted blood flow to vital organs such as the heart."

In some operations, a procedure called acute normovolemic hemodilution, is performed to avoid exposing the patient to allogeneic blood (donated by other people). acute normovolemic hemodilution involves removing a few units of the patient's own blood immediately prior to surgery and saving it for re-administration during or after surgery. This process decreases the oxygen-carrying capacity of the patient's circulating blood. The cardiovascular system has various ways of compensating for this deficiency, for instance by increasing the heart rate. However, blocked or constricted arteries in patients with coronary artery disease can hinder the body's compensatory processes, thereby putting these patients at greater risk of complications during surgery.

Animal studies have shown that acute normovolemic hemodilution below a hemoglobin concentration of 7.5 g/dL is associated with heart dysfunction, such as a decreased ability to pump blood. A pharmacology study presented by Dr. Standl investigated the ability of Hemopure to enhance tissue oxygenation in the heart during a 90 percent constriction, or stenosis, of the left anterior descending artery. In this study, 18 dogs were hemodiluted to a hemoglobin concentration of 7 g/dL and were randomized into three treatment groups. The results showed that the mean oxygen tension (a measure of tissue oxygenation) dropped significantly (21+/-6 mm Hg before vs. 7+/-6 mm Hg after constriction) in animals given Ringer's solution during arterial constriction, remained unchanged (18+/-7 mm Hg) in animals given Hemopure prior to constriction, and was restored to near baseline (23+/-7 before vs. 15+/-5 mm Hg after) in animals given Hemopure after arterial constriction.

The researchers concluded that, since Hemopure sustains heart tissue oxygenation and function during severe coronary artery constriction, the product may prevent cardiocirculatory complications such as heart failure in patients with coronary artery disease undergoing acute normovolemic hemodilution.

Hemopure consists of bovine hemoglobin that has been purified, chemically cross-linked for stability and formulated in a balanced salt solution similar to Ringer's lactate. On a gram-for-gram basis, this cross-linked hemoglobin carries the same amount of oxygen as the hemoglobin in red blood cells. However, these linked hemoglobin molecules circulate in the plasma (the fluid part of blood) and are smaller, have a lower viscosity (resistance to flow) and more readily release oxygen to tissues than red blood cells. Consequently, they have been shown to carry oxygen through constricted or partially blocked blood vessels to areas of the body that are difficult for larger red blood cells to reach.

Biopure is a leading developer, manufacturer and marketer of oxygen therapeutics. These pharmaceuticals are intravenously administered into the circulatory system to deliver oxygen to the body's tissues. Hemopure is an investigational product being evaluated for human use in a pivotal United States Phase III clinical trial as a perioperative alternative to red blood cell transfusion in orthopedic surgery. Other studies are investigating the product's use in trauma and in conditions where tissue oxygenation may be beneficial but blood is not normally transfused, such as heart attack, stroke and hypoxic tumors. Oxyglobin (hemoglobin glutamer -- 200 (bovine)), the only hemoglobin-based oxygen therapeutic approved by the United States Food and Drug Administration, is commercially available in the United States for the treatment of anemia in dogs, regardless of the cause. Both products are stable at room temperature for at least two years, are compatible with all blood types, and are purified to remove potential infectious agents and other contaminants.
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Comment:Study shows Hemopure sustains tissue oxygenation and heart function during severe constriction of coronary artery.
Publication:BIOTECH Patent News
Geographic Code:1USA
Date:Oct 1, 1999
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