TUESDAY, Nov. 6, 2007 (HealthDay News) -- A shot in the arm may be just what the doctor prescribed to control high blood pressure.
Researchers presenting Tuesday at the American Heart Association annual meeting in Orlando, Fla., report initially encouraging results with a vaccine that would obviate the need to take drugs every day.
"It was a small dose, and the trial was done in a conservative way, but there was not only safety and tolerability -- we also had efficacy with blood pressure," said study author Dr. Juerg Nussberger, a professor of medicine at University Hospital of the Canton of Vaud in Lausanne, Switzerland.
Nussberger also has an interest in Cytos Biotechnology, which makes the vaccine.
"The big hope is that you could give a few doses, and that would be it for life, then you wouldn't have some of the compliance issues related to taking medications on a daily basis," added Dr. Daniel Jones, president of the American Heart Association. "Safety is the key thing. If this is proven safe, I really can't think of a downside."
Almost one in three Americans suffers from high blood pressure, which increases the risk of stroke, heart disease, heart failure and kidney failure.
"Only 37 percent of Americans [with hypertension] have controlled blood pressure," Jones said.
Part of the problem may be the difficulty for patients of following complex medication regimens.
In fact, a study presented earlier at the meeting found that simplifying treatment for hypertension helped more patients control their blood pressure than did working within national guidelines (65 percent in the simplified group versus 53 percent in the other arm).
"The problem is that lifelong, they have to take a pill a day," Nussberger said. "If you can give them a shot, they go home and . . . later they come back. It would be a good thing."
This new vaccine, known as CYT006-AngQb, works by inhibiting angiotensin II, a molecule that constricts blood vessels and raises blood pressure. Several existing medications target the same molecule, including ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin receptor blockers).
For this trial, 72 volunteers with mild to moderate high blood pressure were injected with 100 or 300 micrograms (ug) of the vaccine or a placebo at zero, four and 12 weeks from the start of the trial. Volunteers included 65 men and seven women, average age 51.5 years.
Patients who received either dose of the vaccine produced antibodies against angiotensin II after the first injection. The response was significantly higher in those who received the higher dose and was also relatively longer-lived.
After 14 weeks, systolic blood pressure (the top number in a reading) in the high-dose group was reduced by 5.6 mm Hg and diastolic blood pressure (the bottom number) fell by 2.8 mm Hg.
And there was another, unexpected benefit: The vaccine appeared to dampen the typical blood pressure surge that occurs between 5 a.m. and 8 a.m., lowering systolic blood pressure by 25 mm Hg and diastolic blood pressure by 13 mm Hg in that time period.
The wee hours of the morning are the most dangerous time to have high blood pressure as it raises the risk of heart attack and stroke, experts noted.
The vaccine also produced only a slight increase in renin levels. Renin is an enzyme that is thought to cause inflammation and may play a role in kidney failure.
The vaccine needs further testing, especially to see if the body would be allowed any "escape mechanism" that would allow it to raise blood pressure if and when needed.
And, even with vaccines, the patient has to agree to the treatment. "Even with the safest and most effective vaccines today, compliance is not 100 percent," Jones said.
For more on high blood pressure, head to the American Heart Association.