Blood pressure combo works, but has side-effects

By Maggie Fox, Health and Science Editor

WASHINGTON, July 19 (Reuters) - A new combination of blood pressure drugs from Novartis (NOVN.VX) (NVS.N) lowers blood pressure more than either alone, researchers reported on Thursday, but outside experts said the side-effects may limit their use.

The two drugs, sold under the brand names Tekturna and Diovan, both lower blood pressure via the kidneys. When Tekturna won U.S. Food and Drug Administration approval last March, it was the first new blood pressure drug approved in more than 10 years.

Tekturna and Diovan together helped more than 49 percent of patients to get to a target blood pressure of 140/90, Dr. Suzanne Oparil of the University of Alabama at Birmingham and colleagues reported in the Lancet medical journal. They previously reported their findings at a meeting of the American College of Cardiology in March.

"This proportion of patients was significantly more than with either drug alone (37.4 percent Tekturna, 33.8 percent Diovan)," Novartis, which funded and designed the study of 1,700 patients, said in a statement.

But the combination produced a worrying rise in potassium, which in turn can cause sudden heart death.

Four percent of the patients who got the combination had their potassium levels rise above a level of 5.5 mmol/l, compared to 2 percent of patients who took either drug alone.

Tekturna, known generically as aliskiren, targets renin, a kidney enzyme that triggers a process that can lead to high blood pressure. Diovan, or valsartan, is an angiotensin receptor blocker that acts on the renin system in a different way.

ODD COMBINATION

Drs. Willem Birkenhager of Erasmus University in Rotterdam, Netherlands and Jan Staessen of the University of Leuven in Belgium said the new combination did not lower blood pressure as much as some other combination might have.

"One wonders therefore why Oparil opted to combine aliskiren with valsartan, rather than with a diuretic or a calcium-channel blocker, as recommended by current guidelines," they wrote in a Lancet commentary.

They said the approach might find a "niche" in a few patients.

"However, because of the potential life-threatening side-effects, which require biochemical monitoring, this concept of treatment is unlikely to make it to general practice or even to primary prevention in specialist care," they wrote.

Oparil said the potassium levels in most patients returned to normal by the end of the eight-week study.

"Physicians have managed these mild increases in potassium very successfully for over 20 years," she said in a statement.

As many as 1 billion people globally may have high blood pressure, which raises the risk of stroke, heart disease and kidney failure.

Tekturna, known as Rasilez outside the United States, was developed by Novartis with Swiss biotech company Speedel SPPN.S and has been recommended for approval in the European Union.

Diovan loses its patent in 2012 and Novartis has been looking for drugs to replace it, including pills such as Exforge, which teams Diovan with Pfizer's (PFE.N) blood pressure drug Norvasc.

((Editing by Leslie Gevirtz; Maggie.Fox.Reuters.com@reuters.net; Washington Newsroom 202-898-8300)) Keywords: HEART PRESSURE/NOVARTIS

(C) Reuters 2007. All rights reserved. Republication or redistribution ofReuters content, including by caching, framing or similar means, is expresslyprohibited without the prior written consent of Reuters. Reuters and the Reuterssphere logo are registered trademarks and trademarks of the Reuters group ofcompanies around the world.nN19432429