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Medical Edge Newspaper Column from Mayo Clinic
GENETIC RESEARCH MAY HELP DOCTORS ‘INDIVIDUALIZE’ MEDS
DEAR MAYO CLINIC: I have heard of a test that helps to determine whether someone will have problems taking medicines. I have trouble with all types of meds. What is the test? How do I find the information so my doctor can help me? — Ohio
ANSWER: Right now, there is no single test to help predict how you will react to all medications. However, significant research is under way. This area of research is called pharmacogenetics — using genetics to help physicians identify which drugs, at what doses, might be most appropriate for a patient on the basis of his or her genetics.
The hope is that pharmacogenetics may help doctors to “individualize” medications.
In January 2005, the U.S. Food and Drug Administration approved a blood test to analyze two genes, CYP2D6 and CYP2C19. These genes encode proteins called enzymes that help the body to metabolize specific drugs. Results from the test allow the physician to consider the patient’s unique genetic information when selecting and prescribing those drugs — but only those specific drugs. The test is called AmpliChip CYP450 Test. This may be the test you heard about.
This genetic profile can be very helpful. Individual differences in these two genes can result in poor or very fast metabolism of individual members of several categories of drugs including some antidepressants, antipsychotics, cardiac antiarrhythmics, beta blockers, pain medications, antinausea drugs and medications used to treat cancer — but only selected agents within those drug categories.
These variations in metabolism can cause real problems. For example, patients who metabolize codeine — a pain reliever — too quickly to its active form, morphine, are at risk of a dangerous overdose, while patients who metabolize codeine too slowly would not receive pain relief because they would not form morphine.
Ask your doctor if this test or other genetic tests for drug response could be helpful to guide your medication therapy. Please remember that each test is drug-specific and does not apply to many other drugs, even those in the same general class. Continue to look for information because pharmacogenetics is evolving quickly.
— Richard Weinshilboum, M.D., Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minn.
Additional Resources:
More information on pharmacogenetics
READERS: About half of the estimated 4 million Americans with glaucoma aren’t aware they have the condition. Not knowing could mean a loss of vision.
Glaucoma isn’t a single disease, but a group of diseases. The common feature of these diseases is pressure-induced damage to the optic nerve, a bundle of nerve fibers that connect the back of the eye to the brain.
The first sign of glaucoma you may notice is loss of peripheral vision. But by then, vision loss is usually significant and permanent. Your eye-care provider can detect glaucoma during routine eye exams, before vision loss occurs.
If glaucoma is diagnosed early, treatments are typically effective in stopping or significantly slowing vision loss. Eyedrops and oral drugs can be used to decrease eye pressure. Surgery is an option if other treatments aren’t effective.
If you’re over age 40, schedule a glaucoma screening every two to four years. Over age 65, schedule a screening every year or two.
If you’re at high risk for glaucoma, your doctor could recommend earlier or more frequent screenings. Risk factors are a family history of the disease, African ancestry, diabetes, certain rare eye diseases and having had an eye injury or having used any corticosteriod preparation for a prolonged period.
Additional Resources:
Treatment of glaucoma
Appointment Information
More Information
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Medical Edge from Mayo Clinic is an educational resource and doesn’t
replace regular medical care. To e-mail a question, go to www.mayoclinic.org,
or write: Medical Edge from Mayo Clinic, c/o TMS, 2225 Kenmore Ave.,
Suite 114, Buffalo, N.Y., 14207. For health information, visit www.mayoclinic.com.
© 2005 TRIBUNE MEDIA SERVICES, INC.
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