New drug could be cure for common cause of high blood pressure

Millions of people with high blood pressure stand to benefit from a new drug that has stunned doctors by reversing a common cause of the condition for years after patients stopped taking the medication.

Patients who took the drug, called baxdrostat, saw their blood pressure improve during a six- to 12-month course of the daily pills, but unexpectedly the benefits remained up to two years later, with some patients no longer on any hypertension drugs and potentially cured of the condition.

“It’s very exciting to see,” said Prof Morris Brown, a hypertension specialist at Queen Mary University of London, who led the study. “Just under a quarter of the patients came off all treatment and had completely normal blood pressure.”

More than a billion people worldwide have high blood pressure, or hypertension, including more than 12 million in the UK. In 5 to 10% of cases, the condition is caused by small nodules or benign tumours on the adrenal glands that cause them to overproduce a hormone called aldosterone. The excess hormone raises blood pressure by signalling the kidneys to retain salt.

The standard treatment for what is called primary aldosteronism is to surgically remove the affected adrenal gland, but other factors can contribute to the patient’s hypertension, meaning surgery is not always a complete cure.

Baxdrostat is known as an aldosterone synthase inhibitor (ASI) which suppresses the blood pressure-raising hormone. The drug was approved in the US earlier this year for patients with hypertension that is not controlled by existing drugs. It is being assessed by the National Institute for Health and Care Excellence (Nice), which could make the drug available through the NHS next year.

The potentially curative effect of baxdrostat came to light in a small study that followed 14 patients whose hypertension improved dramatically during a three-month trial of the drug. They continued taking the daily pills for six to 12 months and then stopped. When doctors checked the patients up to two years later, their blood pressure was still lower. Details are published in the New England Journal of Medicine.

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Mason Freeman, a professor of medicine at Harvard University, who was involved in the work, said it was too early to say if some of the patients were cured and a larger trial was under way to find out. “If this effect is common and very persistent then the approach to diagnosing and treating these patients is likely to dramatically change,” he said. “Everyone could be treated with the ASI in initial suspicion of the condition and if they responded well they could avoid the invasive diagnostic procedures and the surgery.”

Brown suspected the drug may cure primary aldosteronism because of an experiment in mice 20 years ago. It showed that deleting the gene needed to make aldosterone led to the loss of cells that churned out the hormone.

He suspects baxdrostat has a similar effect. When the drug suppresses aldosterone it causes a surge in highly active molecules called reactive oxygen species. These may selectively destroy the cells that overproduce the hormone.

“Those oxygen radicals are killing the cells and they disappear,” Brown said. “That’s what I think the mechanism is and it’s testable, it’s something we’re doing now in the laboratory.”