Researchers at St. Michael's Hospital have published the first detailed figures showing the risk of using the prescription drug Rasilez in combination with certain other blood pressure-lowering medications.
The pharmaceutical company Novartis terminated a large, international clinical trial of the drug last month after finding an increased incidence after 18-24 months of non-fatal strokes, renal complications, high levels of potassium in the blood and low blood pressure.
As a result, Health Canada said on Dec. 22 that it would review the safety of Rasilez, the brand name for aliskiren.
Even before Novartis halted its clinical trial, Dr. Ziv Harel and other researchers at St. Michael's were examining the interaction between Rasilez and angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blocker (ARB) drugs.
After reviewing 10 large randomized clinical trials on the combination of these drugs, they found that patients taking Rasilez as well as an ACE inhibitor or ARB, had about a 50 per cent greater risk of developing hyperkalemia - high levels of potassium in the blood - than those taking only an ACE inhibitor or ARB.
As well, patients taking a combination of Rasilez plus an ACE inhibitor or ARB had a 70 per cent greater risk of developing hyperkalemia than those taking Rasilez alone. Hyperkalemia can lead to an irregular heartbeat or increased risk of cardiac arrest.
Their analysis of the clinical trials was fast-tracked into publication this week in the British Medical Journal. It provided the first specific data of the risks of taking the drug combinations. Data was released from the halted Novartis trial, but a detailed analysis was not reported.