Erythropoietin
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Epogen

Erythropoietin (EPO) is a glycoprotein hormone that is a growth factor for erythrocyte (red blood cell) precursors in the bone marrow. It increases the number of red blood cells in the blood. Synthetic erythropoietin is available as a therapeutic agent produced by recombinant DNA technology. It is used in treating anemia resulting from chronic renal failure or from chemotherapy for the treatment of cancer. Its use is also believed to be common as a blood doping agent in endurance sports such as bicycle racing, triathlons and marathon running. more...

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Discovery and Biological Role

The existence of a humoral factor regulating red blood cell production was first postulated in 1906 based on transfusion experiments in rabbits. In 1950, the still unidentified erythropoietic factor was found to be stimulated in rats breathing a low-oxygen atmosphere, thus establishing the elements of its biological regulation. In the 1960s its source was identified as the kidneys. The human hormone was first purified in 1977 from human urine and a small amount was used experimentally to treat patients with anemia.

EPO has now been identified as a glycoprotein with a molecular mass of about 30,000 Daltons. It has a 165 amino acid chain with four oligosaccharide side chains and circulates in the blood plasma at a very low concentration (about 5 pmol/L).

In adult humans, EPO is produced primarily by peritubular cells in the kidneys, where its production is stimulated by low oxygen levels in the blood. Some EPO is also produced by the liver, which is the primary source in the fetus.

EPO acts by binding to a specific erythropoietin receptor (EpoR) on the surface of red cell precursors in the bone marrow, stimulating them to transform into mature red blood cells. As a result the oxygen level in blood reaching the kidney rises and the amount of EPO produced decreases.

Because the kidneys are the primary source of erythropoietin, chronic kidney disease often results in a systemic deficiency of EPO and consequent anemia. Anemia can also occur in cancer patients, sometimes as a direct result of the malignancy but usually as a side effect of chemotherapy.

Also, in patients who may require a blood transfusion or undergo surgery where blood loss is expected, EPO is given in advance as a precaution. The bone marrow produces more red blood cells, and if blood is lost during the operation, there is still enough to sustain the patient.

EPO as a Therapeutic Agent

A portion of the human EPO isolated from urine in 1977 was acquired by Amgen, Inc., an American biotechnology company. In 1983, the gene coding for it was identified at Amgen just weeks ahead of a corporate rival, allowing the company to establish a dominant patent position in the field after an epic legal battle. Recombinant DNA technology was used to express the protein in Chinese hamster ovary cells, which allowed a synthetic form of EPO (rEPO) to be produced in commercial quantities for the first time.

Recombinant EPO was launched as a pharmaceutical product by Amgen for treatment of anemia resulting from chronic kidney disease in 1989 under the brand name Epogen. In 1991 it was also approved for treating anemia resulting from cancer chemotherapy. Johnson & Johnson (J&J), an American pharmaceutical company, markets EPO under license from Amgen for cancer chemotherapy under the brand name Procrit. Amgen’s patents have so far prevented other companies from entering the US market. Even though the patents are all based on work done in the early 1980s, the last of them will not expire until 2015, thirty-two years after the date of the original application.

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Case law illustrates liability issues for counterfeit drugs
From Drug Store News, 3/7/05 by Michelle L. Kirsche

SOUTH BEDMINSTER, N.J. -- What will happen tomorrow when a person today fills a prescription at the local pharmacy and the drug turns out to be a counterfeit? Pharmacy retailers already have faced the issue and present examples of an emerging area of case law based on potential liability for manufacturers and distributors of prescription drugs.

John Gilbert Jr., a former attorney for the Drug Enforcement Agency and now a principal at a boutique law firm specializing in food and drug law, presented some of the first legal cases to address liability issues surrounding counterfeit drugs at last month's thought leadership conference sponsored by BuzzeoPDMA, a division of Dendrite.

Gilbert, with the law firm Hyman, Phelps & McNamara, said that in the case against one major chain, a consumer tried to bring a class-action suit against it and its distributor, alleging they sold counterfeit Lipitor. The court found that the consumer, or plaintiff, had not suffered and was not likely to suffer any actual harm, which would be required to make the case.

"It may be a bit of an anomaly, but it's interesting to see how these cases are going to start being brought and what the courts are going to look at as far as whether they are going to establish liability here, said Gilbert. "And this particular court said, You tell me this is a counterfeit drug, and it may be, but we don't see any harm. The court to me was saying to look at the traditional situations where you file injunctive relief or try to get a temporary restraining order--that area of law means you have to show harm. And the court is going to apply those traditional legal elements to those cases.

Citing another case that concerns a 16-year-old patient who was prescribed Epogen after an emergency liver transplant, Gilbert said the patient received a counterfeit drug from another drug chain. Amgen, the maker of Epogen, has been dismissed from the case. Upon its decision, however, the case will be one of the first to define potential liability of manufacturers, distributors and pharmacies for injuries from counterfeit drugs.

"As far as I know, currently the case is still going forward against the wholesaler and the pharmacy as far as trying to determine liability," Gilbert said.

He also offered details on a third case that holds future ramifications. The case concerned Pfizer, which filed suit against several drug distributors, claiming that its drugs had been counterfeited by the distributors or the distributors had sold counterfeit versions of its drugs.

In that case, the U.S. Food and Drug Administration intervened because it had a criminal investigation under way and was concerned about a civil case spilling out information and hurting the FDA's case.

"This is an illustration that, as companies are trying to move forward bringing their own lawsuits, there are going to be issues as to where the cases are if you have a group like the FDA or DEA involved in an investigation," said Gilbert. "Government would welcome manufacturers taking on the expense of pursuing this, but at the same time, the feds have never liked it when private industry gets involved in their investigations."

COPYRIGHT 2005 Reproduced with permission of the copyright holder. Further reproduction or distribution is prohibited without permission.
COPYRIGHT 2005 Gale Group

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