Hypertension Vaccine in the Works

March 7, 2008 -- A vaccine for high blood pressure is in the works.

The experimental vaccine doesn't have a brand name yet. It's designed to help treat -- not prevent -- high blood pressure (hypertension).

In a preliminary study, the high blood pressure vaccine curbed early morning blood pressure in patients with mild-to-moderate hypertension.

The vaccine spurs the body to make antibodies that target a protein called angiotensin II, which helps constrict blood vessels. By sidelining angiotensin II, blood vessels stay more relaxed, keeping blood pressure lower.

There are drugs that act on angiotensin II. But some high blood pressure patients don't take their medicines as instructed, hence the interest in a blood pressure vaccine.

Hypertension Vaccine

The preliminary study focused, first and foremost, on the vaccine's safety.

The study included 72 adults with mild-to-moderate hypertension. Over three months, they got either three injections of a high dose of the vaccine, three injections of a low dose of the vaccine, or three injections of a placebo.

The patients got their first shot when the study started, a second dose a month later, and the third dose three months after the study began. They also got their blood pressure monitored around the clock at the study's start and again two weeks after their last shot.

No serious side effects were linked to the vaccine. Adverse events were generally mild and included injection site reactions and flu-like symptoms.

Further Studies Needed

The study wasn't designed to test the vaccine's effectiveness. But the results show a drop in early morning blood pressure with the higher dose of the vaccine.

Longer, larger studies are needed to further test the vaccine.

If the vaccine fares well in those tests, patients would need "a few injections per year," write the researchers, who included Alain Tissot, PhD, of Cytos Biotechnology AG, the Swiss company that makes the vaccine and funded the study.

An editorial published with the study in The Lancet cautions that the study was "small and exploratory" and that further safety and effectiveness tests are needed.

"Nevertheless, the results of this new biotherapy for hypertension are intriguing and promising, and vaccination for hypertension may turn out to be very useful in many patients," write the editorialists, who included Ola Samuelsson, MD, of Sahlgrenska University Hospital in Goteborg, Sweden.