Thousands of Canadians with high blood pressure are taking a combination of drugs that increases their risk of sudden cardiac death, kidney disease and other complications, the Heart and Stroke Foundation warned Friday.
Under new Canadian guidelines, patients taking a combination of ACE inhibitors and Angiotensin II Receptor Blockers (ARBs) should not stop taking the medications on their own, but should see their family doctor as soon as possible to discuss whether to change treatment.
Angiotensin Converting Enzyme or ACE inhibitors such as Ramipril are a type of blood pressure medication that helps widens blood vessels, making it easier for blood to flow through.
Angiotensin II Receptor Blockers (ARBs) block the action of a peptide called angiotensin, which causes blood vessels to narrow, helping to relax the blood vessels and lower blood pressure.
Combination stresses kidneys
"There is a synergy that happens when you use this particular drug combination but, unfortunately, it is not a synergy that benefits patients," said Toronto nephrologist Dr. Sheldon Tobe, a spokesperson for the Heart and Stroke Foundation and an executive member of the committee that drafted the new guidelines.
| Commonly used blood pressure medications in Canada ACE Inhibitors |
| Benazepril (Lotensin®) |
| Captopril (Capoten®) |
| Cilazapril (Inhibace®) |
| Enalapril (Vasotec®) |
| Fosinopril (Monopril®) |
| Lisinopril (Prinvil®, Zestril®) |
| Perindopril (Coversyl®) |
| Ramipril (Altace®) |
| Trandolapril (Mavik®) |
| Angiotension Receptor Antagonist (ARB) |
| Candesartan (Atacand®) |
| Eprosartan (Teveten®) |
| Irbesartan (Avapro®) |
| Losartan (Cozaar®) |
| Telmisartan (Micardis®) |
| Valsartan (Diovan®) |
| Source: Canadian Hypertension Education Program |
"When you put the two drugs together, you don't get any additional protection against heart attacks and strokes and you get more negative side-effects," he added.
The drug combination is a major source of stress on the kidneys, said Margaret Moy Lum-Kwong, a spokersperson for the Heart and Stroke Foundation of Ontario who leads the group's high blood pressure strategy.
The side-effects may include fainting, diarrhea and elevated levels of potassium that could result in the need for dialysis, or death.
"The good news is that for patients who are on this particular combination treatment, that once you stop the combination, the risk is eliminated," Lum-Kwong said.
She added that people should know what medications they are on and why..
As many as 175,000 Canadians with high blood pressure may be currently treated with this combination of medications.
Most people with hypertension need to take two or more drugs and adopt a healthier lifestyle, according to the committee that draws up guidelines, the Canadian Hypertension Education Program.
But a Canadian-led trial, called On Target, published in the New England Journal of Medicine in April 2008 found the drug combination was only marginally better at lowering blood pressure than either drug alone, and patients taking both experienced more side-effects such as kidney problems.
The trial included 25,620 people who were age 55 or older with vascular disease or high-risk diabetes.
In updating the guidelines, the committee also considered other studies to understand the scope of the potential problem, Lum-Kwong said.
High blood pressure affects one in five Canadians, according to the foundation.
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