Aug. 26, 2008 -- The drug allopurinol, often prescribed to lower uric acid levels in adults who suffer the painful arthritic condition known as gout, also appears to help lower high blood pressure in teens, according to a new study.
However, the study's lead author emphasizes he is not suggesting that the powerful drug, which can have serious side effects, be used in teens with high blood pressure. He conducted the study to test the hypothesis that lowering uric acid levels can lower blood pressure in teens.
"I really don't want this [study] to be taken to suggest that allopurinol is a good alternative for treatment of blood pressure in children or adults," says Daniel I. Feig, MD, PhD, associate professor of pediatrics at the Baylor College of Medicine in Houston. The drug is too potent, he and other experts say, and the risk of serious side effects make it unattractive to use long-term in teens.
If future, larger studies also find that lowering uric acid in teens with high blood pressure normalizes their pressure, Feig says, "the impetus will be ... to find better ways to lower uric acid, whether by dietary means or by medications."
The study is published in Wednesday's Journal of the American Medical Association.
Uric Acid and Blood Pressure: The Back Story
Buildup of uric acid, a natural waste product, can lead to a painful inflammation of the joints called gout, a form of arthritis that typically occurs in middle-aged men. Uric acid levels can increase if the body produces more of it or if the body has problems getting rid of it.
Uric acid also has been discussed as a possible factor in high blood pressure since the 1870s, Feig says. But the concept fell out of favor in recent times, until laboratory studies on animals beginning in the late 1990s showed that inducing a rise in uric acid in animals raises their blood pressure. Other studies have found that lowering uric acid levels can improve blood vessel functioning, he says.
Gout Medicine for Teen Blood Pressure
Feig's team randomly assigned 30 teens, aged 11 to 17, with newly diagnosed stage I essential hypertension, the mildest kind, to take either 200 milligrams of allopurinol twice daily for four weeks or a placebo twice daily for four weeks. The teens didn't know which they were taking.
After four weeks, the teens switched groups: Teens taking the placebo got the drug and teens taking the drug got the placebo.
They had their blood pressure taken at the clinic and via an ambulatory monitoring system.
Gout Medicine for Blood Pressure: Study Results
The teens' uric acid levels declined while taking allopurinol. While on the drug, blood pressure dropped, and the differences were significant between the medication and placebo phases, Feig says. "Twenty of 30 children were normotensive [had normal blood pressure] on allopurinol," he says. "On placebo, one of 30 was [at normal blood pressure]."
At the start, the teens' blood pressure readings in the clinic averaged 139/83. During the drug treatment phases, blood pressure decreased by an average of 6.9 points for systolic pressure (the top number of a blood pressure reading) and 5.1 for diastolic pressure (the bottom number). On the placebo, systolic pressure declined by 2 and diastolic pressure declined by 2.4.
Allopurinol for Teen Blood Pressure: Serious Side Effects
Two experts who reviewed the study results for WebMD worried, as Feig did, that the results would be over-interpreted and viewed as a reason to use allopurinol in teens.
"I think the study is well done,'' says Henry Black, MD, president of the American Society of Hypertension and a clinical professor of medicine at the New York University School of Medicine in New York. It found what it set out to prove, he says -- that lowering high uric acid levels can lower blood pressure, at least in this small study.
But he had a caveat: "Allopurinol has some very serious and potentially fatal side effects," he says, including gastrointestinal complaints and a severe, allergic reaction known as Stevens-Johnson syndrome. "It's a leap to consider allopurinol an alternative treatment for high blood pressure in teens."
"This is not a benign medication," agrees Suzanne Steinbaum, DO, a preventive cardiologist and director of Women and Heart Disease of the Heart and Vascular Institute at Lenox Hill Hospital in New York City. "When I give allopurinol to adults, there is a list of side effects [I provide to them]."
For teens, Steinbaum says, the first line of treatment for high blood pressure, as for adults, should be lifestyle improvement -- encouraging them to eat right and to exercise.
Feig agrees that lifestyle comes first. In the study, the teens received advice on how to eat a healthful diet and lose weight.
In his ongoing research, Feig is studying obese teens with pre-hypertension to see if lowering their uric acid will normalize their blood pressure. If the same findings bear out, the next step, he says, is to find better ways to lower uric acid.