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New genetics tool allows customized prescriptions, drug interaction identification

DALLAS, TX., July 31, 2003 -- Paul Sokal, M.D., an internist on the medical staff at Baylor University Medical Center at Dallas, recently announced his use of a new tool designed to assist physicians in customizing drug prescriptions based on an individual patient's unique genetic makeup, as well as identify potential drug interactions.

Known as Signature Genetics, this technology combines the results of genetic testing for a specific patient with scientific knowledge on how genetic variations impact drug metabolism.

"This is a real advance for physicians and patients. We always look for the most appropriate medications and dosages to treat our patients," said Dr. Sokal. "Signature Genetics is an ongoing service that we can use throughout the patient's lifetime as medications are prescribed. We now have a better understanding of what drugs will be effective or problematic. Ultimately, we will see fewer side effects and greater drug efficacy. This is personalized medicine."

First, the patient visits the physician's office and has his or her blood drawn and a cheek swab analysis. These samples are sent to a laboratory. Four to six weeks later, the report, which covers more than 150 of the most commonly prescribed medications, over the counter drugs and herbal remedies metabolized by specific enzymes, known as Cytochrome P450 enzymes, is sent to the physician's office.

This report also provides information on drug interactions with these enzymes. When multiple drugs are given to an individual patient, one drug may interfere with the metabolism of another drug, often rendering the second drug useless or potentially toxic.

Once a patient has been tested and an initial report issued, the physician can easily query Signature Genetics regarding any additional drugs under consideration for that patient. Through this process, the physician receives information specific to both the drug and the patient before actually prescribing the new drug.

Following are examples of how genetic variations impact drug metabolism:
-- Approximately 7 percent of Caucasians experience no pain relief from codeine. These individuals' genetic makeup consists of two copies of a variant gene, which does not produce the enzyme required to convert codeine into morphine, the active pain-relieving agent of codeine.
-- The metabolism of a drug called Warfarin (Coumadin), a blood anticoagulant, is heavily impacted by genetic variations. In this case, incorrect dosages can lead to serious, even fatal, side effects.

Paul Sokal, M.D., is with Dallas Diagnostic Association (DDA) in the Park Cities. DDA is a physician practice with HealthTexas Provider Network, Baylor Health Care System's affiliated physician group.

Source: Baylor Health Care System

Posted: July 2003