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Common antibiotic may control deadly abdominal aortic aneurysm

TAMPA — Imagine walking around with a ticking time bomb inside you. That's how an abdominal aortic aneurysm, also known as an AAA or triple A, is often described.

Like a bubble on a bicycle tire, the balloonlike bulge forms on the main artery that supplies blood to the lower body. There usually are no symptoms, but if the aneurysm bursts, it's fatal 75 percent of the time.

The larger the aneurysm, the greater the risk of rupture and the more likely doctors are to recommend a surgical repair. Small aneurysms — less than 2 inches in size — rarely burst and are watched with ultrasound to monitor when they become large enough to repair.

But what if doctors could prevent small aneurysms from growing larger? Could lives be saved and surgeries prevented?

That's the question researchers hope to answer in a large clinical trial involving a common, safe and inexpensive drug.

"If it works, this could become the go-to treatment for small aneurysms," said Dr. Murray Shames, a vascular surgeon at USF Health Morsani College of Medicine and Tampa General Hospital.

Shames is the principal investigator locally of a trial funded by the National Institutes of Health testing the antibiotic doxycycline. A member of the tetracycline family, the drug long has been used to treat bacterial infections. But in early studies, it also has shown promise for inhibiting growth of aneurysms by blocking enzymes that weaken aortic walls.

"The drug has been used for years in the treatment of acne and gum disease. So we have a lot of experience with it and a lot of research using this drug," Shames said.

It's available as a generic, meaning that as pharmaceuticals go, it's a bargain, though the cost can vary depending on supply. Side effects are few and include sun sensitivity.

More than 27,000 deaths were caused by or related to AAAs in the United States in 2009, according to the Centers for Disease Control and Prevention.

White men ages 65 and older are more likely than women and African-Americans to develop aortic aneurysms. Smokers are at a higher risk, too. Other risk factors include high blood pressure and cholesterol and family history of aneurysms. But aneurysms usually develop and grow larger, about half a centimeter a year, without symptoms.

That's why federal health officials recommend ultrasound screening for high-risk Americans: men age 65 to 75 who smoke, or have ever smoked.

Without such screening, AAAs are usually picked up on scans of the abdomen ordered for unrelated medical issues. Many are not found until it's too late.

It takes about four to five years for an aneurysm to grow large enough for surgery. "You may die of something else, but anyone with a small aneurysm, if they live long enough, will ultimately develop a big aneurysm," Shames said.

Only patients with small aneurysms are eligible for the study. Bernard Remas of Fort Myers was diagnosed with a small AAA in 2007.

"I don't get too scared too often," the 82-year-old former Los Angeles police officer said. "When I retired from law enforcement I thought my worrying was over. But my sister is a nurse and she got real excited when she heard about it."

As part of the study, Remas takes two capsules a day and has periodic blood work and abdominal CT scans to check for changes. He doesn't know if he's getting the study drug or a placebo.

"There's no pain, no reminder that it's there. I take each day and live it until the 11 o'clock news," he said.

It likely will be years before it's clear not only whether the drug therapy is effective, but also which patients are most likely to be helped by it.

Dr. Patrick Cambier, an interventional cardiologist at Morton Plant Hospital in Clearwater, has been treating patients with AAAs for 20 years. Though he finds the hypothesis intriguing and the research important, he says it will take more long-term, large-scale studies before doxycycline could become standard treatment for small AAAs.

Cambier noted there are many reasons AAAs form, including genetics, poorly controlled hypertension, atherosclerosis and diabetes, as well as smoking.

"Many different factors put stress on and can damage the aorta," he said. "Some patients may benefit from this (drug therapy) approach, but without additional research, it remains to be seen how many."

Irene Maher can be reached at imaher@tampabay.com.

Common antibiotic may control deadly abdominal aortic aneurysm 06/08/14 [Last modified: Sunday, June 8, 2014 9:35pm]

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