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Researchers say a drug commonly prescribed for high blood pressure is safe and effective. PIKSEL/Getty Images
  • New research indicates that amlodipine, a widely prescribed medication for hypertension, is unlikely to contribute to significant health risks.
  • Although amlodipine has been prescribed for decades, research in recent years had questioned the drug’s safety.
  • By combining science and epidemiological analysis, researchers concluded that the risks were not significant and were far outweighed by its benefits.

New research is bolstering the safety and efficacy of amlodipine (sold under the brand name Norvasc), one of the most common drugs for treating hypertension (also known as high blood pressure).

Researchers from the U.S. National Institutes of Health (NIH) and Glasgow University in Scotland are reporting that amlodipine – which in 2020 was the fifth-most widely prescribed drug in the United States – is unlikely to carry negative health implications.

The data was published today in the journal Function. The U.S.-based research team received funding from the NIH, while researchers in Scotland were supported by the British Heart Foundation and the UKRI Strength in Places Fund.

The research is considered significant because other recent studies have questioned the safety of amlodipine, suggesting that it could change blood vessels and in turn increase the risk of heart failure.

Experts interviewed by Medical News Today say the new data helps clarify the role that amlodipine plays in people with hypertension, while reaffirming its status as a useful tool for treating the condition.

Why safety of blood pressure medication has been questioned

Anant Parekh, the chief of the Signal Transduction Laboratory and senior investigator at the National Institute of Environmental Health Sciences, was one of the study’s authors.

He told Medical News Today that amlodipine has been widely prescribed to treat hypertension for more than 30 years.

He explained that its mechanism is well understood. It inhibits a type of calcium channel known as a voltage-gated channel and this inhibition relaxes the muscles and widens blood vessels, which reduces blood pressure.

“Recently, another study reported that amlodipine and all other calcium channel blockers opened a different type of calcium channel, the store-operated calcium channel, and this led to vascular remodeling that often occurs in hypertension,” he explained. “Analysis of patients’ records was also conducted in that study, leading to the conclusion that amlodipine increased the risk of heart failure. This led the study to conclude that the use of amlodipine in patients should be reconsidered.”

Researchers noted that this study used high concentrations of the drug, more than 100-fold higher that the therapeutic dose. In order to better understand this connection, they zeroed in on amlodipine’s interactions with the store-operated calcium channels.

They said a detailed meta-analysis of clinical trials, along with a real world analysis of more than 60,000 hypertensive patients, found no evidence for an increased risk of heart failure.

Dr. Cheng-Han Chen, an interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in California who was not involved in the study, told Medical News Today that the most recent data helps clarify some of the mixed messages surrounding amlodipine.

“The conclusions they were making previously were almost like a misinterpretation of what the laboratory data was saying. When I looked at [the new study], it showed that amlodipine was safe and effective in patients with hypertension with and without heart failure, and using it wouldn’t contribute to heart failure. So it answers the question from two different directions.

Why amlodopine can be a useful drug

Parekh pointed out that these new findings are in line with clinicians’ best-practice advice.

“My mother has been taking amlodipine for several years, and we noticed that when she ran out or forgot to pack the pills while traveling, her blood pressure would increase, often significantly,” he said. “Talking to physicians in the U.K. and elsewhere, I was reassured that none had seen adverse effects of calcium channel blockers and numerous meta-analyses had shown the drug was effective in reducing hypertension without indications of heart failure. This is also what I was learning in medical school. The study I referred to earlier was in conflict with a substantial body of literature and with physicians’ real-world experience.”

While the data indicates that amlodipine is unlikely to contribute to heart failure, Parekh said that there are plans to continue this research.

“Although our study shows that amlodipine and other calcium channel blockers do not activate store-operated calcium channels, we would like to see whether these channels do contribute to cardiovascular disease,” he said. “If they do, then the channels could be an attractive drugable pharmaceutical target for treating various problems with the circulatory system.”

Bringing clarity to high blood pressure drugs

Experts say the new data is welcome news for patients and doctors alike who have relied on amlodipine for decades.

“We definitely should not be thinking, based on the previous information, that we should pull back our usage of amlodipine, because then we’ll be dealing with much more serious consequences in terms of patients with high blood pressure,” said Chen.

Parekh said that the study’s value comes from a combination of basic science along with a large analysis of people with hypertension.

“The basic science provides a detailed mechanistic insight, but is of limited value to patients as the relevance to hypertensive humans is unclear,” he explained. “The clinical research is directly relevant to patients but does not provide an understanding of the underlying mechanisms at a cellular level. It is the combination of both approaches that brings great clarity. Both aspects of the study – basic science and epidemiological analysis – took a significant amount of time, but were important to persevere given the overall impact this research can have on patients.”