As a cardiovascular disease therapy, it works by lowering blood pressure in vessels feeding the heart. High blood pressure is also associated with the development of Alzheimer’s, studies have shown.
How Telmisartan works
Telmisartan is an angiotensin II receptor antagonist, also known as an angiotensin II receptor blocker (ARB) or a sartan. These molecules bind to the angiotensin II receptor, blocking its action. Angiotensin II receptor blockers help relax blood vessels, lowering blood pressure and making it easier for the heart to pump blood.
Studies have shown that angiotensin receptor antagonists can reduce the risk of Alzheimer’s in a rodent model. Researchers believe telmisartan can slow the progression of Alzheimer’s by controlling blood flow, protecting capillary blood vessels, and reducing plaque formation in the brain — a hallmark of the disease.
Telmisartan in clinical trials
Two clinical trials are assessing whether telmisartan can help treat Alzheimer’s.
One is an open-label Phase 2 study (NCT02085265 nicknamed SARTAN-AD) evaluating telmisartan’s ability to treat 240 people with mild to moderate Alzheimer’s.
Some of the trial participants are taking telmisartan while others are taking another blood-pressure-lowering therapy, perindopril. Perindopril is an angiotensin-converting enzyme (ACE) inhibitor which works to prevent the creation of angiotensin II in order to keep it from narrowing blood vessels. Patients will be given either oral medication for a year.
The trial is assessing telmisartan’s safety and ability to widen blood vessels as a way of slowing the brain atrophy that characterizes Alzheimer’s. Researchers are also looking at whether telmisartan can improve patients’ cognitive and functional abilities, changes in electrolytes in the blood, its impact on the volume of a brain region called the hippocampus, and whether it changes the proportion of gray versus white matter in the brain.
The trial, being conducted in Canada, is still recruiting and is expected to be completed by March 2021.
The eight-month trial, nicknamed HEART, involves 66 middle-aged African-Americans who are susceptible to developing Alzheimer’s because they have high blood pressure and a parent with Alzheimer’s. Researchers are randomly assigning the patients to either 20 mg or 40 mg of telmisartan once a day, or a placebo.
The primary objective of the study is to see whether telmisartan can lower the level of angiotensin metabolites in the fluid surrounding the brain and spinal cord. The metabolites are associated with blood-vessel constriction.
One of the secondary objectives of the study is assessing telmisartan’s impact on patients’ cognitive abilities. Another is to see how the therapy affects biomarkers associated with Alzheimer’s, such as the level of tau protein. An accumulation of that protein is linked to brain deterioration.
The trial, being conducted at Emory University, is still recruiting and is expected to run through June of 2020.
Last updated: Sept. 5, 2019
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