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In an age of blockbuster drugs, this is being hailed as a gamechanger for patients with high blood pressure (BP) that cannot be controlled effectively by existing pills. Now Phase III clinical trials by the University College of London (UCL) have shown that a new drug – baxdrostat – can significantly lower resistant hypertension, thereby reducing the risk of heart attacks, strokes and kidney disease.
This is significant as globally more than 1.3 billion people have hypertension. “The arrival of baxdrostat in the group of blood pressure-lowering drugs is a therapeutic advance that will enable clinicians to achieve better control of high blood pressure and associated conditions,” says Dr K Srinath Reddy, honorary distinguished professor at Public Health Foundation of India (PHFI).
Why is the study significant?
The BaxHTN study, which was conducted on 796 patients from 214 clinics worldwide, showed that those taking baxdrostat had a blood pressure fall by about 9-10 mmHg (millimetres of mercury, the unit of measurement of blood pressure) more than placebo in 12 weeks. About four in 10 patients taking the drug – as a 1 mg or 2 mg daily tablet – reached normal blood pressure levels, compared with fewer than two in 10 on placebo. A 10 mmHg reduction is significant as it can substantially lower risk of heart attack, stroke, heart failure and kidney disease.
The findings were presented at the European Society of Cardiology congress in Madrid, the world’s largest heart conference.
What is resistant hypertension?
This is a condition where your blood pressure continues to be above target despite treatment with at least three different blood pressure medications, including a diuretic, at maximally tolerated doses. Sometimes this happens because of a high-sodium diet, excessive alcohol intake, obesity and physical inactivity. But mostly, it is because of excess levels of a hormone called aldosterone. The adrenal glands produce too much of it, leading to high blood pressure, low potassium and high sodium.
How does the new pill work on your body?
Aldosterone is an important hormone because it maintains the body’s electrolyte balance. Excess of it, however, prods the body to hold salt and water. This increased volume pushes up blood pressure.
“Aldosterone helps to retain sodium in the body while preventing high potassium levels. But excess secretion of aldosterone or high receptor sensitivity to its action results in extra sodium retention in the body and changes how blood vessels react to it. This leads to high blood pressure which can lead to brain strokes, heart attacks, heart failure and kidney dysfunction. Aldosterone-receptor blocking drugs have been used in the treatment of high blood pressure and heart failure,” says Dr Reddy.
Why the pill holds out hope
The new drug is an improvement because it is targetted at blocking aldosterone production altogether. “For years, existing drugs have been prescribed to block the effects of aldosterone and eliminate excess fluid and salt without causing a significant loss of potassium. Now we have a drug that goes to the root of the problem, stops aldosterone production,” says Dr Ranjan Shetty, lead cardiologist at Sparsh Hospitals, Bengaluru.
In fact, the latest American Heart Association guidelines on blood pressure mandate that patients must undertake the aldosterone to renin (kidney enzyme that regulates blood pressure) ratio test to help diagnose hyperaldosteronism or excess levels of the hormone. “Since this test is still very expensive, we do a symptomatic assessment of resistant hypertension and give aldosterone-limiting drugs. That takes care of the problem in most cases. Now we have a better alternative,” says Dr Shetty.
Also, since the trials were across nations, its efficacy could hold in real time use, he adds.
