Experimental blood pressure vaccine may replace daily pills

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Remembering to take your high blood pressure pills every day can be a burden, especially if you're juggling a list of other prescriptions.

So what if, instead, you could receive a vaccination that would lower your blood pressure for months on end?

Such a vaccine has proven effective in controlling high blood pressure in lab rats for up to six months, according to new research published May 26 in the journal Hypertension.

The experimental DNA vaccine creates antibodies that target angiotensin II, a hormone that raises blood pressure by causing blood vessels to constrict, said co-author Dr. Hironori Nakagami, a professor at Osaka University in Japan.

In that regard, the vaccine is similar to common ACE inhibitor blood pressure medications, which work by helping blood vessels relax and open up, the researchers said.

Nakagami said the vaccine could benefit people who don't take their high blood pressure medication as prescribed.

"The potential of a vaccine for hypertension offers an innovative treatment that could be very effective for the control of noncompliance, which is one of the major problems in the management of hypertensive patients," he said.

According to the Heart and Stroke Foundation, approximately 33% of South Africans suffer from high blood pressure, placing them at a greater risk of heart disease, stroke and premature death.

In the new study, researchers gave the vaccine three times at two-week intervals to rats with high blood pressure.

The vaccine not only lowered blood pressure for up to six months, but also reduced tissue damage to the heart and blood vessels associated with high blood pressure, the study reports. There were no signs of damage to other organs such as the kidney or liver.

"Systolic blood pressure was consistently lower in the DNA vaccine group after immunization, while blood pressure reduction was continued for at least six months," Nakagami said. (Systolic is the top number in a blood pressure reading.)

Read: Many South Africans can't afford a healthy diet

Results need to be demonstrated in humans

While studies involving animals often fail to produce similar results in humans, the research group hopes to have a version of the vaccine ready for human clinical trials within two or three years, Nakagami said.

Researchers suspect that humans likely would need booster shots once or twice a year to maintain the vaccine's effect, he said.

Whether the vaccine would be a better option than existing medications remains to be seen.

About 85 percent of high blood pressure patients now can be treated using available medications, which leaves a significant minority that could be helped with this vaccine, said Dr. Ernesto Schiffrin, vice chair of research at McGill University's department of medicine in Montreal, Canada.

"There remains always a group of patients where you use three, four agents or more and you still don't have blood pressure at goal," he said. "There will always be opportunity for the development and application of new medications, and we should strive to develop new ones because there is a need."

However, how long the vaccine can control high blood pressure between shots will be key in determining whether it's more worthwhile than the cheap, safe and effective pills now available, Schiffrin added.

"High blood pressure pills are not that expensive," Schiffrin said. "They're all generic now, and they are being used quite extensively around the world. The question is, how long will the vaccine last? How effective will it be? And will there be any adverse effects?"

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